Journal of Clinical and Diagnostic Research, ISSN - 0973 - 709X

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Dr Mohan Z Mani

"Thank you very much for having published my article in record time.I would like to compliment you and your entire staff for your promptness, courtesy, and willingness to be customer friendly, which is quite unusual.I was given your reference by a colleague in pathology,and was able to directly phone your editorial office for clarifications.I would particularly like to thank the publication managers and the Assistant Editor who were following up my article. I would also like to thank you for adjusting the money I paid initially into payment for my modified article,and refunding the balance.
I wish all success to your journal and look forward to sending you any suitable similar article in future"

Dr Mohan Z Mani,
Professor & Head,
Department of Dermatolgy,
Believers Church Medical College,
Thiruvalla, Kerala
On Sep 2018

Prof. Somashekhar Nimbalkar

"Over the last few years, we have published our research regularly in Journal of Clinical and Diagnostic Research. Having published in more than 20 high impact journals over the last five years including several high impact ones and reviewing articles for even more journals across my fields of interest, we value our published work in JCDR for their high standards in publishing scientific articles. The ease of submission, the rapid reviews in under a month, the high quality of their reviewers and keen attention to the final process of proofs and publication, ensure that there are no mistakes in the final article. We have been asked clarifications on several occasions and have been happy to provide them and it exemplifies the commitment to quality of the team at JCDR."

Prof. Somashekhar Nimbalkar
Head, Department of Pediatrics, Pramukhswami Medical College, Karamsad
Chairman, Research Group, Charutar Arogya Mandal, Karamsad
National Joint Coordinator - Advanced IAP NNF NRP Program
Ex-Member, Governing Body, National Neonatology Forum, New Delhi
Ex-President - National Neonatology Forum Gujarat State Chapter
Department of Pediatrics, Pramukhswami Medical College, Karamsad, Anand, Gujarat.
On Sep 2018

Dr. Kalyani R

"Journal of Clinical and Diagnostic Research is at present a well-known Indian originated scientific journal which started with a humble beginning. I have been associated with this journal since many years. I appreciate the Editor, Dr. Hemant Jain, for his constant effort in bringing up this journal to the present status right from the scratch. The journal is multidisciplinary. It encourages in publishing the scientific articles from postgraduates and also the beginners who start their career. At the same time the journal also caters for the high quality articles from specialty and super-specialty researchers. Hence it provides a platform for the scientist and researchers to publish. The other aspect of it is, the readers get the information regarding the most recent developments in science which can be used for teaching, research, treating patients and to some extent take preventive measures against certain diseases. The journal is contributing immensely to the society at national and international level."

Dr Kalyani R
Professor and Head
Department of Pathology
Sri Devaraj Urs Medical College
Sri Devaraj Urs Academy of Higher Education and Research , Kolar, Karnataka
On Sep 2018

Dr. Saumya Navit

"As a peer-reviewed journal, the Journal of Clinical and Diagnostic Research provides an opportunity to researchers, scientists and budding professionals to explore the developments in the field of medicine and dentistry and their varied specialities, thus extending our view on biological diversities of living species in relation to medicine.
‘Knowledge is treasure of a wise man.’ The free access of this journal provides an immense scope of learning for the both the old and the young in field of medicine and dentistry as well. The multidisciplinary nature of the journal makes it a better platform to absorb all that is being researched and developed. The publication process is systematic and professional. Online submission, publication and peer reviewing makes it a user-friendly journal.
As an experienced dentist and an academician, I proudly recommend this journal to the dental fraternity as a good quality open access platform for rapid communication of their cutting-edge research progress and discovery.
I wish JCDR a great success and I hope that journal will soar higher with the passing time."

Dr Saumya Navit
Professor and Head
Department of Pediatric Dentistry
Saraswati Dental College
On Sep 2018

Dr. Arunava Biswas

"My sincere attachment with JCDR as an author as well as reviewer is a learning experience . Their systematic approach in publication of article in various categories is really praiseworthy.
Their prompt and timely response to review's query and the manner in which they have set the reviewing process helps in extracting the best possible scientific writings for publication.
It's a honour and pride to be a part of the JCDR team. My very best wishes to JCDR and hope it will sparkle up above the sky as a high indexed journal in near future."

Dr. Arunava Biswas
MD, DM (Clinical Pharmacology)
Assistant Professor
Department of Pharmacology
Calcutta National Medical College & Hospital , Kolkata

Dr. C.S. Ramesh Babu
" Journal of Clinical and Diagnostic Research (JCDR) is a multi-specialty medical and dental journal publishing high quality research articles in almost all branches of medicine. The quality of printing of figures and tables is excellent and comparable to any International journal. An added advantage is nominal publication charges and monthly issue of the journal and more chances of an article being accepted for publication. Moreover being a multi-specialty journal an article concerning a particular specialty has a wider reach of readers of other related specialties also. As an author and reviewer for several years I find this Journal most suitable and highly recommend this Journal."
Best regards,
C.S. Ramesh Babu,
Associate Professor of Anatomy,
Muzaffarnagar Medical College,
On Aug 2018

Dr. Arundhathi. S
"Journal of Clinical and Diagnostic Research (JCDR) is a reputed peer reviewed journal and is constantly involved in publishing high quality research articles related to medicine. Its been a great pleasure to be associated with this esteemed journal as a reviewer and as an author for a couple of years. The editorial board consists of many dedicated and reputed experts as its members and they are doing an appreciable work in guiding budding researchers. JCDR is doing a commendable job in scientific research by promoting excellent quality research & review articles and case reports & series. The reviewers provide appropriate suggestions that improve the quality of articles. I strongly recommend my fraternity to encourage JCDR by contributing their valuable research work in this widely accepted, user friendly journal. I hope my collaboration with JCDR will continue for a long time".

Dr. Arundhathi. S
MBBS, MD (Pathology),
Sanjay Gandhi institute of trauma and orthopedics,
On Aug 2018

Dr. Mamta Gupta,
"It gives me great pleasure to be associated with JCDR, since last 2-3 years. Since then I have authored, co-authored and reviewed about 25 articles in JCDR. I thank JCDR for giving me an opportunity to improve my own skills as an author and a reviewer.
It 's a multispecialty journal, publishing high quality articles. It gives a platform to the authors to publish their research work which can be available for everyone across the globe to read. The best thing about JCDR is that the full articles of all medical specialties are available as pdf/html for reading free of cost or without institutional subscription, which is not there for other journals. For those who have problem in writing manuscript or do statistical work, JCDR comes for their rescue.
The journal has a monthly publication and the articles are published quite fast. In time compared to other journals. The on-line first publication is also a great advantage and facility to review one's own articles before going to print. The response to any query and permission if required, is quite fast; this is quite commendable. I have a very good experience about seeking quick permission for quoting a photograph (Fig.) from a JCDR article for my chapter authored in an E book. I never thought it would be so easy. No hassles.
Reviewing articles is no less a pain staking process and requires in depth perception, knowledge about the topic for review. It requires time and concentration, yet I enjoy doing it. The JCDR website especially for the reviewers is quite user friendly. My suggestions for improving the journal is, more strict review process, so that only high quality articles are published. I find a a good number of articles in Obst. Gynae, hence, a new journal for this specialty titled JCDR-OG can be started. May be a bimonthly or quarterly publication to begin with. Only selected articles should find a place in it.
An yearly reward for the best article authored can also incentivize the authors. Though the process of finding the best article will be not be very easy. I do not know how reviewing process can be improved. If an article is being reviewed by two reviewers, then opinion of one can be communicated to the other or the final opinion of the editor can be communicated to the reviewer if requested for. This will help one’s reviewing skills.
My best wishes to Dr. Hemant Jain and all the editorial staff of JCDR for their untiring efforts to bring out this journal. I strongly recommend medical fraternity to publish their valuable research work in this esteemed journal, JCDR".

Dr. Mamta Gupta
(Ex HOD Obs &Gynae, Hindu Rao Hospital and associated NDMC Medical College, Delhi)
Aug 2018

Dr. Rajendra Kumar Ghritlaharey

"I wish to thank Dr. Hemant Jain, Editor-in-Chief Journal of Clinical and Diagnostic Research (JCDR), for asking me to write up few words.
Writing is the representation of language in a textual medium i e; into the words and sentences on paper. Quality medical manuscript writing in particular, demands not only a high-quality research, but also requires accurate and concise communication of findings and conclusions, with adherence to particular journal guidelines. In medical field whether working in teaching, private, or in corporate institution, everyone wants to excel in his / her own field and get recognised by making manuscripts publication.

Authors are the souls of any journal, and deserve much respect. To publish a journal manuscripts are needed from authors. Authors have a great responsibility for producing facts of their work in terms of number and results truthfully and an individual honesty is expected from authors in this regards. Both ways its true "No authors-No manuscripts-No journals" and "No journals–No manuscripts–No authors". Reviewing a manuscript is also a very responsible and important task of any peer-reviewed journal and to be taken seriously. It needs knowledge on the subject, sincerity, honesty and determination. Although the process of reviewing a manuscript is a time consuming task butit is expected to give one's best remarks within the time frame of the journal.
Salient features of the JCDR: It is a biomedical, multidisciplinary (including all medical and dental specialities), e-journal, with wide scope and extensive author support. At the same time, a free text of manuscript is available in HTML and PDF format. There is fast growing authorship and readership with JCDR as this can be judged by the number of articles published in it i e; in Feb 2007 of its first issue, it contained 5 articles only, and now in its recent volume published in April 2011, it contained 67 manuscripts. This e-journal is fulfilling the commitments and objectives sincerely, (as stated by Editor-in-chief in his preface to first edition) i e; to encourage physicians through the internet, especially from the developing countries who witness a spectrum of disease and acquire a wealth of knowledge to publish their experiences to benefit the medical community in patients care. I also feel that many of us have work of substance, newer ideas, adequate clinical materials but poor in medical writing and hesitation to submit the work and need help. JCDR provides authors help in this regards.
Timely publication of journal: Publication of manuscripts and bringing out the issue in time is one of the positive aspects of JCDR and is possible with strong support team in terms of peer reviewers, proof reading, language check, computer operators, etc. This is one of the great reasons for authors to submit their work with JCDR. Another best part of JCDR is "Online first Publications" facilities available for the authors. This facility not only provides the prompt publications of the manuscripts but at the same time also early availability of the manuscripts for the readers.
Indexation and online availability: Indexation transforms the journal in some sense from its local ownership to the worldwide professional community and to the public.JCDR is indexed with Embase & EMbiology, Google Scholar, Index Copernicus, Chemical Abstracts Service, Journal seek Database, Indian Science Abstracts, to name few of them. Manuscriptspublished in JCDR are available on major search engines ie; google, yahoo, msn.
In the era of fast growing newer technologies, and in computer and internet friendly environment the manuscripts preparation, submission, review, revision, etc and all can be done and checked with a click from all corer of the world, at any time. Of course there is always a scope for improvement in every field and none is perfect. To progress, one needs to identify the areas of one's weakness and to strengthen them.
It is well said that "happy beginning is half done" and it fits perfectly with JCDR. It has grown considerably and I feel it has already grown up from its infancy to adolescence, achieving the status of standard online e-journal form Indian continent since its inception in Feb 2007. This had been made possible due to the efforts and the hard work put in it. The way the JCDR is improving with every new volume, with good quality original manuscripts, makes it a quality journal for readers. I must thank and congratulate Dr Hemant Jain, Editor-in-Chief JCDR and his team for their sincere efforts, dedication, and determination for making JCDR a fast growing journal.
Every one of us: authors, reviewers, editors, and publisher are responsible for enhancing the stature of the journal. I wish for a great success for JCDR."

Thanking you
With sincere regards
Dr. Rajendra Kumar Ghritlaharey, M.S., M. Ch., FAIS
Associate Professor,
Department of Paediatric Surgery, Gandhi Medical College & Associated
Kamla Nehru & Hamidia Hospitals Bhopal, Madhya Pradesh 462 001 (India)
On May 11,2011

Dr. Shankar P.R.

"On looking back through my Gmail archives after being requested by the journal to write a short editorial about my experiences of publishing with the Journal of Clinical and Diagnostic Research (JCDR), I came across an e-mail from Dr. Hemant Jain, Editor, in March 2007, which introduced the new electronic journal. The main features of the journal which were outlined in the e-mail were extensive author support, cash rewards, the peer review process, and other salient features of the journal.
Over a span of over four years, we (I and my colleagues) have published around 25 articles in the journal. In this editorial, I plan to briefly discuss my experiences of publishing with JCDR and the strengths of the journal and to finally address the areas for improvement.
My experiences of publishing with JCDR: Overall, my experiences of publishing withJCDR have been positive. The best point about the journal is that it responds to queries from the author. This may seem to be simple and not too much to ask for, but unfortunately, many journals in the subcontinent and from many developing countries do not respond or they respond with a long delay to the queries from the authors 1. The reasons could be many, including lack of optimal secretarial and other support. Another problem with many journals is the slowness of the review process. Editorial processing and peer review can take anywhere between a year to two years with some journals. Also, some journals do not keep the contributors informed about the progress of the review process. Due to the long review process, the articles can lose their relevance and topicality. A major benefit with JCDR is the timeliness and promptness of its response. In Dr Jain's e-mail which was sent to me in 2007, before the introduction of the Pre-publishing system, he had stated that he had received my submission and that he would get back to me within seven days and he did!
Most of the manuscripts are published within 3 to 4 months of their submission if they are found to be suitable after the review process. JCDR is published bimonthly and the accepted articles were usually published in the next issue. Recently, due to the increased volume of the submissions, the review process has become slower and it ?? Section can take from 4 to 6 months for the articles to be reviewed. The journal has an extensive author support system and it has recently introduced a paid expedited review process. The journal also mentions the average time for processing the manuscript under different submission systems - regular submission and expedited review.
Strengths of the journal: The journal has an online first facility in which the accepted manuscripts may be published on the website before being included in a regular issue of the journal. This cuts down the time between their acceptance and the publication. The journal is indexed in many databases, though not in PubMed. The editorial board should now take steps to index the journal in PubMed. The journal has a system of notifying readers through e-mail when a new issue is released. Also, the articles are available in both the HTML and the PDF formats. I especially like the new and colorful page format of the journal. Also, the access statistics of the articles are available. The prepublication and the manuscript tracking system are also helpful for the authors.
Areas for improvement: In certain cases, I felt that the peer review process of the manuscripts was not up to international standards and that it should be strengthened. Also, the number of manuscripts in an issue is high and it may be difficult for readers to go through all of them. The journal can consider tightening of the peer review process and increasing the quality standards for the acceptance of the manuscripts. I faced occasional problems with the online manuscript submission (Pre-publishing) system, which have to be addressed.
Overall, the publishing process with JCDR has been smooth, quick and relatively hassle free and I can recommend other authors to consider the journal as an outlet for their work."

Dr. P. Ravi Shankar
KIST Medical College, P.O. Box 14142, Kathmandu, Nepal.
On April 2011

Dear team JCDR, I would like to thank you for the very professional and polite service provided by everyone at JCDR. While i have been in the field of writing and editing for sometime, this has been my first attempt in publishing a scientific paper.Thank you for hand-holding me through the process.

Dr. Anuradha
On Jan 2020

Important Notice

Year : 2021 | Month : July | Volume : 15 | Issue : 7 | Page : LE01 - LE07 Full Version

Anti-SARS-CoV-2 Antibody Seroprevalence Surveys in India: An Insight into Current COVID-19 Pandemic Situation

Published: July 1, 2021 | DOI:
Sudarshan Ramaswamy, Arpit Arora, Aditya Athotra, Meera Dhuria, Arti Bahl, Anil Digambar Patil, Sudhir Kumar Jain, Sujeet Kumar Singh

1. Consultant (NO-A)-Health Emergencies, World Health Organisation, WCO, New Delhi, India. (Posted in Department of Epidemiology, NCDC) . 2. Research Scholar, Department of Centre for Technology Alternatives for Rural Areas, IIT Bombay, Mumbai, Maharashtra, India. 3. Statistical Officer, Statistical Monitoring and Evaluation Cell, National Centre for Disease Control (NCDC), New Delhi, India. 4. Deputy Director, Department of Epidemiology, National Centre for Disease Control (NCDC), New Delhi, India. 5. Joint Director, Department of Epidemiology, National Centre for Disease Control (NCDC), New Delhi, India. 6. Additional Director and Head, Statistical Monitoring and Evaluation Cell, National Centre for Disease Control (NCDC), New Delhi, India. 7. Additional Director and Head, Department of Epidemiology, National Centre for Disease Control (NCDC), New Delhi, India. 8. Director, National Centre for Disease Control (NCDC), New Delhi, India.

Correspondence Address :
Meera Dhuria,
Deputy Director, Department of Epidemiology, National Centre for Disease Control, 22, Sham Nath Marg, Delhi, India.


Antibody test is used in seroprevalence surveys for Coronavirus Disease-2019 (COVID-19). Apart from estimating the proportion of population infected, they can help in drawing plenty of inferences about the extent, progress and course of the pandemic. They can potentially be helpful in planning and prioritising vaccine distribution by providing a broad overview into proportion of population immune to COVID-19 in a geographic area and also help in understanding the pockets of high or low seroprevalence. This review was conducted with an aim of compiling an updated and comprehensive information about the seroprevalence of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) antibody in various pockets of India in the year 2020, and thus to understand the current pandemic situation in the country. A total of 35 studies were identified through all resources and detailed review was carried out based on these studies. Additionally, indicators were devised to understand and compare the results. Results were further classified into states/Union Territories (UTs), districts, Sub-district regions. The study findings show that the anti SARS-CoV-2 antibodies seroprevalence estimates vary across different regions (states/UTs, districts, sub district regions) of India and can increase or in some instances decrease over the course of time. The study concludes by asserting the need for repeated seroprevalence surveys as well as follow-up studies for current pandemic surveillance.


Herd immunity, Infection case ratio, Seroepidemiologic studies, Vaccination

Ever since the announcement of the efficacy of few COVID-19 vaccines through the interim analysis of placebo-controlled phase III trials (mid phase), a sigh of relief and a ray of hope on moving back to normalcy from the current pandemic situation has been felt across the world. Nevertheless, even after approval of vaccines, one of the major challenges for public health experts remains the distribution of vaccines across the population throughout the world. As various countries are developing their vaccine introduction and national deployment plans for COVID-19, stress is laid upon introducing vaccination in phased manner by defining age-based, risk specific prioritisation of population subgroups (1). COVID-19 vaccination rollout in India shall be a nuance operation and unique in its own way since it requires more extensive coverage than previously conducted vaccination drives such as “Pulse Polio Immunisation” or “Measles Rubella (MR) campaign” in which target group was a subset of population (under-5 children) unlike the COVID-19 vaccination program which demands much more extensive coverage across all age groups. However, providing vaccination on priority basis to those subgroups of population who are at high risk contacting infection (front line healthcare professionals) or mortality (persons over 60 years of age and persons between 45 and 59 years with comorbid conditions) is being considered (2).

Seroprevalence surveys can provide a broad overview into proportion of population immune/not immune to COVID-19 in that geographic area and also help in understanding the pockets of high or low seroprevalence, potentially helpful in planning and prioritising vaccine distribution. Secondly, effectiveness of any immunisation program in the general population after introduction of the vaccine not only depends on monitoring the efficacy and safety of the vaccine (phase 4 trials) but also depends upon immunisation coverage. Moreover, the knowledge of herd immunity threshold for COVID-19 vaccine is necessary for effective immunisation coverage. ‘herd immunity’, also known as ‘population immunity’, is a concept used for vaccination, in which a population can be protected from a certain virus if a threshold of vaccination is reached (3). Based on the existing evidence from seroprevalence studies across the world, herd immunity threshold due to natural infection too is quite early to call (4). Duration of persistence of immunity after natural infection/after single dose of vaccination and after multiple/booster doses shall also thus influence the effectiveness of immunisation program. Repeated seroprevalence surveys and follow-up studies, hence provide a parallel (may be earlier) insight into estimation of herd immunity threshold as well as antibody behaviour; both of which influence the effectiveness of immunisation programs (5).

The review aimed to compile an updated and comprehensive information about the seroprevalence of the anti SARS-CoV-2 antibody in various pockets of India in the year 2020, from the data available so far, and thus to understand the current pandemic situation in the country. The overall objective was aimed at providing a compiled base of reference for future analysis of serological studies, potentially helpful in planning, distribution, monitoring the effectiveness of COVID-19 vaccines in India.


The National Library of Medicine's PubMed database and Google scholar database was searched to identify potentially relevant publications. The search limits included all the seroprevalence studies conducted in India during the year 2020. The community-based (among general population) seroprevalence studies either published as articles in peer-reviewed journals or Government reports or whose results were presented by the States in COVID-19 review meetings conducted by Ministry of Health and Family Welfare (MoHFW), Government of India (GoI) during the year 2020 were included (Table/Fig 1) (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),(30),(31),(32),(33),(34),(35),(36),(37),(38). Studies done through samples exclusively taken from hospitals or among Healthcare Worker (HCWs) or from diagnostic laboratories were excluded.

As on December 20, 2020 the authors searched National Library of Medicine (NLM) database using the following terms “(Seroprevalence or Serosurvey) and (COVID-19 OR anti SARS-CoV2 or SARS-CoV2) AND (India)”. The search results showed 14 articles and three (10),(21),(32) among them fit the selection criteria. The authors also searched Google scholar database using the following terms "Seroprevalence", "India", "COVID-19” which resulted 703 articles and all the 13 studies that fit into the selection criteria were included. Unpublished data was also searched, available in public domain regarding various COVID-19 (anti SARS-CoV2 antibodies) seroprevalence surveys in India through google search (11),(12),(14),(16),(19),(26),(27),(28),(29),(34),(35),(36),(37). The relevant data were collected through various state government websites of health and family welfare, official websites of organisations involved in seroprevalence surveys across the country, press briefings, media reports and sources from National Center for Disease Control (NCDC), Directorate General of Health Services (DGHS), MoHFW, Delhi staff attending the regular review meetings on COVID-19 by MoHFW.

Validity assessment was not done since the data consisted of different stages of studies (published articles, unpublished data, press reports etc.), samples belonged to different epidemiological distribution (time, place and person) and conducted during different phases of the pandemic. The data obtained from literature search was classified as published articles (peer-reviewed academic journals), government reports and by personalised communication from the NCDC. The authors found results of serological surveys from a total of 33 studies through all sources. Among them, 16 were from peer-reviewed journal articles (with 18 sets of data as data from Brehampur and Bhubaneshwar (16) included in one article and data from Delhi in August and September (19) taken from one article) (10),(11),(12),(14),(16),(19),(21),(26),(27),(28),(29),(32),(34),(35),(36),(37), four were from government reports (with five sets of data as data from Haryana in August and October (20) included in one report) (18),(20),(31),(33) and nine were from review meetings (with 10 sets of data as data for Punjab and Ludhiana (24) included in one meeting report) (Table/Fig 1) (13),(15),(17),(22),(23),(24),(25),(30),(38). As all the serosurveys included were officially conducted by respective governments either directly or through partner agencies, and few of them yet to be published/under the process of publication in peer reviewed journals, alternatively newspaper articles were considered for knowing the estimated prevalence and sample size. Data obtained from all the studies were compiled in MS Excel and a detailed review was done.

Results have been grouped into six geographic zones of India according to the existing administrative “Zonal Councils” that were set up vide part-III of the States Reorganisation Act, 1956 (6). Results were further classified into States/UTs, District, Subdistrict regions. An estimate of number of infections based on the projected population of the district/region (as per macrotrends website) (7) was made for all the studies. Infection Case Ratio (ICR), Case Fatality Rate (CFR) and Infection Fatality Rate (IFR) were also calculated. CFR and IFR were calculated based on the average time for seroconversion (14 days) and average time of death after infection (21 days) respectively (8),(9).

C=Number of reported cases on (Mid-point of survey-14 days)

I= Population of the district/region×seroprevalance/ 100, ICR=I/C

CFR= Number of deaths reported on (Mid-point of survey-14 days) / Number of cases reported on (Mid-point of survey-14 days) ×100

IFR=Number of deaths on (Mid-point of survey-7 days) / 1 ×100

• The number of expected infections (I) has been calculated based on the seroprevalence values based on the projected population of the district/region (as per macrotrends website) (7). Intending to maintain uniformity and for comparison across the studies, calculation of infections for all the districts/states/towns has been done based on the 2011 census population data projected for 2020 (mid-year) acquired from a single website whose data source is United Nations - World Population Prospects (7).
• Mean time for seroconversion is 12-14 days for IgG after onset of symptoms for total antibody (8). Hence, a 14-day gap is considered between the reporting of cases and the actual seroprevalence.
• Studies have shown that mean duration from onset of symptoms to death due to COVID-19 as 18 days (9). Considering 2-3 days delay in reporting deaths, 21 days was conveniently used as the gap between case reporting and mortality (14+7 days).

Overall average for all the three parameters calculated has been compared with the two nationwide serosurvey results conducted by ICMR (10),(11).


Central zone: In Indore, a serosurvey was conducted in the month of August with a sample size of 7,100. Stratified random sampling was used to collect the samples and Indian Council of Medical Research (ICMR)-Kavach IgG ELISA kits were used for detecting the presence of antiodies in the samples. The study was conducted for 15 days and collected samples from all 85 wards in the city. Overall weighted sero prevalence of 7.75% (12). Adopting a similar sampling strategy, serosurvey was conducted in Bhopal in September where 7,976 samples were collected and the overall weighted sero prevalence of 18.02% was reported for the city (13). On similar methodological lines, Jabalpur conducted a city-wide sero survey in the month of December. Out of the 9000 samples collected, 28.7% of the sample population showed positive antibody results (14).

A serosurvey was conducted in Uttar Pradesh during the month of September, in which 16,000 participants were tested. The samples were equally distributed among the top 11 districts with highest COVID-19 caseprevalence, from which 22.1% of the samples showed antibodies against the SARS-CoV-2 (15).

East zone: In Odisha, during the month of August, serosurveys were conducted in Berhampur and Bhubaneshwar with asample size of 2830 and 1320, respectively. Participants above 18 years were selected for the study. Twenty-five clusters were identified in each city based on population proportional to size. Multi-stage clustered sampling was used to identify the participants. The seroprevalence for Berhampur and Bhubaneshwar was found to be 31.30% and 5.15% respectively. Participants working in manufacturing sector were found to have higher seroprevalence for both, Bhubaneshwar (9.67%) and Berhampur (39.16%) (16),(17).

Based on the study methodology adopted for serosurvey in August, another serosurvey was conducted in Bhubaneshwar in October. 1,403 samples were collected using a multi stage clustered sampling approach from 25 clusters in the city. A 50% of the samples showed positive results in the seropositivity tests (17).

North zone: Till date four serosurveys have been carried out and effectively completed in Delhi. First serosurvey was conducted in July, where 21,387 samples were collected and tested based on multi-staged systematic sampling approach. Samples were distributed across all the 11 districts based on proportional population (18),(19). The overall seroprevalence from the study was 23.48% (18). Subsequently, in the next three serosurveys, a total of 15,046, 17,407 and 15,015 participants were tested during August, September, and October respectively (19). The selection of participants in all three studies was through a multi-stage sampling design from all the 11 districts and 280 wards of the city, with two-stage allocation proportional to population-size. The households were selected via systematic random sampling, and individual participants were selected through the age-order procedure. The inclusion criteria of participants was age >5 years, residing in Delhi for at least the past six months and have not participated in previous serological surveys. The seroprevalence was 28.45%, 25.10%, and 25.06%, respectively (19).

Two state-wide serosurveys were carried out in Haryana in August and October. Both the serosurveys covered all 22 districts of the state. In the first serosurvey, 18905 samples were collected and analysed using stratified multi-stage sampling approach. Samples were equally divided among all the 22 districts (850 per district) with 60% and 40% distribution of samples among rural and urban areas respectively for each district. All the participants were above 18 years of age. Overall seroprevalence for the state was 8% with huge district-wise variations. In the second study, 16,512 (720 per district) samples were tested. Overall seropositivity for the state during October was 14.8% (20).

In the Union Territory of Jammu and Kashmir, the first study carried out in July was restricted to Srinagar. A total of 2,906 persons aged >18 years were selected from hospital visitors across Srinagar District. The overall seroprevalence was found to be 3.6% (21). Next serosurvey was conducted in October and all 10 districts of Kashmir were included. 6,200 people tested during the study and the results revealed a seroprevalence of 39% (22).

In Punjab, the first sero-survey was conducted across five containment zones during the month of August from which 27.7% of the sampled population (1250, 18 years of age) had developed antibodies against the virus (23). The containment zones were selected on the basis of highest number of COVID-19 cases and the samples were equally divided. Another serosurvey was conducted across 12 districts of Punjab in November in which 4,678 samples were tested. Each district was given a sample size of 400 with equal distribution among urban and rural areas. The seroprevalance in urban areas was found to be 30.5%, while in rural areas it was 21%. The overall seroprevalence across the State was found to be 24.19% and the district of Ludhiana was found to have the highest overall seroprevalence of 54.6% (71.7% in urban areas) (24).

North-east zone: In a serosurvey conduced by an NGO in different districts of Assam during the month of September, 23.7% of the state’s population was found to have been exposed to the SARS-CoV-2 virus. The districts were stratified into three categories high, medium and low risk, and 2,390 samples were collected for the study (25).

South zone: In a state-wide serosurvey carried out in Karnataka in the month of August, 46.7% of the population was found to have antibodies against the Sars-Cov-2 virus. The comparative study found that seroprevalence in rural areas was 44.1% and 53.8% in urban areas. Different sampling approaches were used for rural and urban areas. In case of urban areas, 21 Census Enumeration Blocks (CEBs) were chosen for each town via a simple random selection. Within each CEB, systematic random sampling was used to identify households for sample collection. However, in case of rural areas, households were first identified based on central street followed by systematic random sampling as in the case of urban areas. A total 1,374 samples were collected during the study froum 20 out of 30 districts in the state (26). Another state-wide serosurvey was carried out in the month of September, which involved 16,416 participants aged ≥18 years across all the 30 districts. The population was stratified into three risk groups based on community exposure and vulnerability to COVID-19. All participants were subjected to simultaneous detection of SARS-CoV-2 IgG using a commercial ELISA kit, SARS-CoV-2 antigen using a Rapid Antigen Detection Test (RAT), and Reverse Transcription-Polymerase Chain Reaction (RT-PCR) for RNA detection. The overall seroprevalence in the state was found to be 27.3% (27).

A serosurvey was conducted during the month of July in Chennai involving 12,405 participants in which 18.40% of the total samples were found to have developed antibodies against the virus (28). Another serosurvey was conduced in October in Tamil Nadu with 26,640 participants. The overall seroprevalence was found to be 31.6%, with Chennai showing a seroprevalence of 40.94% (26,135 samples) (29).

In Andra Pradesh, a state-wide serosurvey was carried out in August, with a sample population of 5000 for each of the 13 districts. A 19.7% of the population sampled were found to have developed antibodies against the virus. In case of urban areas, the seroprevalence was found to be 22.5%. In case of rural areas, 18.2% of the sample population was found to have developed immunity against the virus. In terms of gender, similar seropositivity was observed in case of females (19.9%) and males (19.5%) (30).

In a joint study, conduced by ICMR and National Institute of Nutrition in 3 districts of Telangana, 12.2% of the sampled population was found to have developed antibodies. Total 1,309 sample were collected for the study- 454 people in Jangaon, 433 in Kamareddy and 422 in Nalgonda. The highest seroprevalence was found in Jangaon district (18.2%) (31).

West zone: In Mumbai, two serosurveys were conducted in successive months of July and August respectively. In the study carried out in July, slum and nonslum communities from three wards-Matunga, Chembur West, and Dahisar—were identified for sample collection. Individuals over age 12 were eligible for the study. 6,904 participants (4,202 from slums and 2,702 from non-slums) were tested using representative sampling approach. The seroprevalence in slums (54.1%) was found to be 3 times higher than non-slums (16.1%). For the study carried out in August, 5,200 samples were analysed from the same three wards with no sampling carried out in active containment zones. The study estimated that 44.9% of the slum population and 17.5% of the non-slum population was exposed to the virus (32),(33). In Aurangabad, a study to identify seropreavalence was carried out across the district. Total sample size of 6,571 individuals above 18 years of age was selected. Samples from slums and non slums were taken based on population proportional to size. Estimated seropreavalence in the district was found to be 5.81% (34).

In a cross-sectional sero study carried out in five highest case incidence wards in the district of Pune, 51.5% of the sampled population showed immunity against the virus. Total of 1,664 participants were included in the study (35). In the region of Pimpri-Chinchwad, a serosurvey on 5000 participants (all above 12 years of age) was conducted in October. The study used population proportionate cluster sampling for selection of participants. A 50, 80 and 70 clusters were chosen for slums, tenements, and housing societies respectively. The overall seropositivity for IgG antibodies was 35% (36).

Successive serosurveys were conducted in Ahmedabad during the months of July and August. In July, 30,000 samples were collected while in August 10,000 samples were taken and the seroprevalence in July was 17.6%, which jumped by 5.6% to 23.24% in August (37),(38).

The overall average ICR from all studies listed was 81.42, as compared to 107.9 and 48.38 as calculated in (Table/Fig 1) for the nation-wide surveys conducted in May and August, respectively. Serosurvey conducted in Punjab during August resulted in the highest ICR at 494.35, and the one carried out in Pimpri, Maharashtra was found to have the lowest ICR of 7.1 (23),(36). Similarly, the overall average of CFR from all the studies included was 2.42% as compared to the nation-wide studies carried out by ICMR, at 2.8% and 1.9% for May and August, respectively (10),(11). Among the included studies, highest CFR of 6.5% was observed in Ahmedabad during the month of July, whereas the lowest CFR of 0.3% was recorded in Assam for the month of September (25),(37). The overall average IFR from all studies listed was 0.073%, as compared to 0.054% and 0.051% obtained from the nationwide surveys conducted in May and August, respectively (Table/Fig 1) (10),(11),(12),(13),(14),(15),(16),(17),(18),(19),(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),(30),(31),(32),(33),(34),(35),(36),(37),(38). Aurangabad and Assam recorded the highest (0.310%) and lowest (0.006%) IFR, respectively (25),(34).

A summary of all the studies described above is shown in (Table/Fig 1) (8),(9),(10),(11),(12),(13),(14),(15),(16),(17),(18),(19),(20),(21),(22),(23),(24),(25),(26),(27),(28),(29),(30),(31),(32),(33),(34),(35),(36),(37),(38). It was noticed that seroprevalence was higher in urban areas as compared to rural areas in almost all the studies (10),(11),(20),(27),(29) which reported comparative assessment involving both sections. Similarly, in all studies (10),(11),(19),(28),(32),(33) showing slum vs non-slum comparisions, it was noticed that seroprevalance was higher in slums/overcrowded areas than non-slum areas. There was no significant gender disparity in seroprevalence overall. The seroprevalence across age-groups was variable across the studies but the age group between 40-60 years was noticed to be the highest seroprevalent age group in many studies.


Seroprevalence: This review shows that seroprevalence estimates of the anti SARS-CoV-2 antibodies vary across different regions of India (states/UTs, districts, sub district regions) and increased over the course of time. For instance, serial studies conducted in Bhubaneshwar (16),(17), Ahmedabad (38), Chennai [28,29] the two ICMR nationwide surveys (10),(11) show an increasing trend. However, some instances have shown a decreasing trend in serial studies such as in Punjab (23),(24), Karnataka (26),(27), Mumbai (32),(33). Repeated serosurveys in Delhi (18),(19) have shown a variable pattern and more or less a consistent trend over the period of time in the year 2020.

While a positive trend (increase in seroprevalence over time) could be attributed to the spread of the disease, witnessing a negative trend (decrease in seroprevalence over time) have raised several questions. Serial serosurveys in Delhi give a good picture of both these phenomena happening simultaneously. One of the probable explanations for a negative trend could be fading away of antibodies over the course of time. It is consistent with several serial seroprevalence studies and longitudinal follow-up studies which have shown declining prevalence of anti SARS-CoV-2 antibody detection over time (4),(5),(39),(40),(41),(42). A longitudinal follow-up study conducted by Oxford university during the early phases of the COVID-19 pandemic concludes that IgG antibody levels to SARS-CoV-2 nucleocapsid wane within months, much faster in younger adults and those without symptoms. The study also estimates that the mean antibody half-life to be 85 days (43). Additionally, case reports suggestive of possibility of clinically recovered patients failing to be seropositive, occasional reports of COVID-19 reinfection and with the evidences of virus mutating into more severe forms (variants of concern - increasing transmission/virulence/resistance to neutralising antibodies) suggest that the pandemic is still far from being over (44),(43),(44),(45),(46),(47). Hence, it is very essential to aggressively re-emphasise the importance of basic COVID-19 appropriate preventive measures (physical distancing, wearing masks, maintenance of respiratory etiquette, hand sanitisation, consumption of nutritious food, prevention of non-communicable diseases through lifestyle modification and medication adherence) and counter the risk-communication fatigue in the community (48). There is a need to focus on implementing preventable and modifiable risk factors (as mentioned above), simultaneously understanding the changes in disease dynamics expected as a result of non-modifiable factors pertaining to the agent (e.g., mutations) and host (e.g., duration of antibody response). Hence, ensuring the inculcation of COVID-19 appropriate behaviour, attitude and perception is to be highly recommended universally, irrespective of prior infection. Repeated seroprevalence surveys/ follow-up studies are essential for pandemic situation update, regular monitoring and surveillance is necessary for identification of any changes indynamics of the current pandemic.

Seroprevalence and related indicators: Highly variable estimates of ICR/CFR/IFR were noticed among different seroprevalence surveys and also as compared to the national surveys or the overall average obtained by various listed surveys. This difference can be attributed to the fact that the studies under consideration are not a true representation of the socio-demographic landscape of India. The studies are from various pockets across India and represent different timelines/phases of the pandemic. High ICR (number of infections per case) implies that the proportions of actual infections being detected as cases are being less. Although detection of all the asymptomatic cases could be a very tough task to ask for, improving the proportion of cases detected through contact tracing shall reduce/slower the spread of COVID-19 disease. Having high ICR also can be reflected as high CFR. While high ICR/CFR imply that case detection and extent of contact tracing needs improvement, a higher CFR/IFR additionally stresses upon the need to enhance the healthcare infrastructure and manpower. Continuous serial monitoring of these indicators are recommended until the pandemic settles down because they can give preliminary indications of any potential influences requiring change in pandemic response activities in the country.

Seroprevalence surveys and vaccination: Though Phase 3 vaccine trials show promising results, vaccine effectiveness in general population is yet to be seen (Phase 4 trials) (49). Apart from effectiveness, it is important to know the herd immunity threshold for vaccination coverage. Seroprevalence surveys so far have resulted in no clear-cut idea about herd immunity. Hopes of natural herd immunity at seroprevalence level as high as 66% estimate after the 1st wave of COVID-19 in Manaus, Brazil has resulted in disappointment due to resurgence of the virus observed as a second wave of COVID-19 cases (4),(5),(50). Such instances have raised questions about the extent of vaccination coverage needed for obtaining herd immunity status. Published literature suggests that duration of anti SARS-CoV-2 antibodies last much shorter in India (51).

All these factors suggest that continuous serosurveillance is very much essential during the phase of vaccination in India as well. Hence, one of the biggest challenges lying ahead for public health experts is amplifying vaccination coverage and simultaneously educating people on a large scale for continuing COVID-19 appropriate behaviours even during post-vaccination phase; until a clear-cut picture on effectiveness of seroconversion is obtained through longitudinal follow-up studies. Nonetheless, as COVID-19 vaccine is provided on a voluntary basis, good vaccination coverage in a quick succession can be established only through an effective participation from the community. Since the vaccination program is already being implemented in a full-fledged manner, a continuous sensitisation of the community addressing the issues of COVID-19 vaccination intent, perceptions and reasons for not getting vaccinated/vaccine hesitancy is highly recommended.


The population used to calculate total number of infections and thus ICR or IFR, do not use the exact population used while calculating the sample size of respective studies. For maintaining uniformity across different studies, calculations have been done based on the projected population for 2020 acquired from a single website.


It is recommended to intensify serological studies and simultaneously apply the knowledge and understanding thus obtained for faster recovery from the situation of debacle we are currently in. Continuous seroprevalence studies and longitudinal follow-up studies have to be done in purview of understanding the various facets of this disease such as the extent of disease spread among the population, herd immunity threshold levels of COVID-19, pattern of serological response to infection, duration of antibody stay in the body, indications of any potential variations of concern (through seroprevalence related indicators), response to vaccination and associated aspects. Furthermore, seroprevalence studies undertaken particularly on Indian population shall be of greater importance as genetic factors too can possibly influence these components.


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DOI and Others


Date of Submission: Jan 22, 2021
Date of Peer Review: Mar 04, 2021
Date of Acceptance: May 10, 2021
Date of Publishing: Jul 01, 2021

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