Original article / research
Changing Epidemiology of Influenza in Post COVID-19 Era: A Retrospective Observational Study
DC12-DC17
Correspondence
Dr. Vaibhavi Pushkar Matkari,
A-1805, Rustomjee Azziano, Majiwada, Thane West, Thane, Maharashtra, India.
Email: vaibhavinanoty@gmail.com
Introduction: Coronavirus Disease (COVID-19) is a highly transmissible viral infection and has challenged the world’s healthcare systems. COVID-19 co-infections with other respiratory pathogens may complicate the diagnosis, treatment and prognosis. Despite Severe Acute Respiratory Syndrome- Coronavirus-2 (SARS-CoV-2) high transmissibility and dominance, influenza circulation persisted throughout the COVID-19 pandemic. Due to their evolving nature and capability to evade the immune system, the available vaccines for these viruses protect from severe disease but not infection. There are varying strains of influenza and SARS-CoV-2 viruses and also their transmission is dynamic over time, thus emphasising the need to continue and expand surveillance across countries for improved decision-making.
Aim: The present study was conducted with a aim to study Severe Acute Respiratory Infections (SARI) and Influenza-like Illness (ILI) with reference to COVID-19 and influenza.
Materials and Methods: The present retrospective observational study was carried out at the tertiary health care centre at Department of Microbiology of Rajiv Gandhi Medical College and Hospital, Kalwa, Thane, Maharashtra, India, from August 2022 to September 2024. The study population includes all patients presenting with ILI and SARI whose samples have been tested for COVID-19 and influenza at the RT-PCR Laboratory during the above-mentioned period. Since it was a retrospective study, the sampling method was consecutive sampling. A total of 1170 patients presenting with ILI and SARI were studied in the given period. Patients of all age groups, presenting at Outpatient Department and hospitalised patients were included in the study. Retrospective analysis of Influenza and SARS-CoV-2 positive cases was carried out. Different clinical and epidemiological parameters were noted. As the data is quantitative in nature, the proportions and percentages were computed accordingly. To study the association of meteorological seasons with that of surge of the Influenza cases, Chi-square test was performed and p-value was noted.
Results: A total of 1170 patients were tested in the given period. Among these 893 presented with SARI and 277 presented with ILI. SARS-CoV-2 infection was found in 61 (6.83 %) of SARI and 35 (12.64%) of ILI patients, respectively. The total Influenza positive cases were 62 (6.94%) in SARI and 61 (22.02%) in ILI patients. SARS-CoV-2 variant was predominant in the year 2022 and Omicron and recombinant XBB variant were predominant in 2023. Significant surge in Influenza cases was seen in monsoon season in 2023. COVID-19 and Influenza co-infection was seen in 2 (0.17%) of 1170 cases. In ILI, 5 (20%) patients having co-morbidities while in SARI 15 (10.34%) patients having co-morbidities were positive for either SARS-CoV-2 or Influenza. Mortality was seen in 2 (3.23%) SARI influenza patients.
Conclusion: Due to the varying circulating strains, seasonal variations of SARS-CoV-2 and influenza viruses, continuous surveillance is essential for management and prevention of SARI and ILI cases.