Anti-Influenza Antibody Level After Vaccination In North Of IranCorrespondence Address :
Abdolvahab Moradi (PhD)Dept. of virology, Golestan University of Medical Scienes,Gorgan city, Golestan province,(Iran)E-mail: email@example.com
Objective:Influenza is a highly transmitted disease and about 10% of the worldâ€™s population is affected by this disease annually. The aim of this research was to study the variation of serum antibody levels among subjects who had already been vaccinated against influenza.
Methods And Materials:This descriptive-analytical study was carried out on 196 subjects who had influenza vaccination (influvac 2005/2006) and on 200 subjects who were matched with the vaccinated subjects by their ages in Gorgan which is located in the northeast of Iran. The subject's sera were prepared seven weeks after the influenza vaccination. Their serum antibody levels were determinated by the heamaglutination inhibition test.
Results:The antibody titre in 81 subjects of the vaccinated group and in 175 subjects of the control group was less then 1/40. The mean antibody titre of the vaccinated subjects and the control group was 143.4Â±10.89 and 18.34Â±3.2, respectively. The difference was statistically significant (P value=0.000).
Conclusion:The findings showed that the mean titre of the antibodies in the vaccinated and control groups was statistically different. This means that the influenza vaccine has good efficacy in our population.
Flu vaccine, Influenza, Iran
Influenza is a highly transmitted disease and about 10% of the worldâ€™s population is affected by this disease annually. Influenza is the sixth reason of death in the world and the forth reason of death in old people.
The virus is continuously undergoing antigenic changes and thus, it can bypass the host's acquired immunity to influenza (1).
The virus causing the disease is transmitted easily by coughing and sneezing, from person to person and spreads very fast in the society. Infection by the influenza virus without signs and symptoms may cause severe diseases or even death.
Almost 30 to 50 percent of the people infected by the virus do not have special signs and symptoms, but they can transmit the disease to others. The best way of prevention is vaccination.
Elderly individuals not only demonstrate a greater risk of morbidity and mortality due to influenza than the young, but also have a greater difficulty in mounting a protective response to the influenza vaccine (2).
The Disease Control Center of America reports that vaccination of people prevents them from getting the disease (70 to 90% of the cases in people under 60 years and 30 to 40% of the cases in people above 60 years old). According to a study in America, in all the 88 subjects who were vaccinated against influenza by the Haemaglutination inhibition test ( HI ), an increase in antibody levels was observed (3).
Increase in antibody titre was observed in 5000 subjects from different ages who were vaccinated against influenza in Poland using the Haemaglotination inhibition test ( HI ) (4).
In a study in France, 21 out of 285 subjects who were vaccinated against influenza showed changes in the levels of antibody serum (5).
In England, changes in the levels of antibody serum were observed in only 18.2% of the 137 subjects who were vaccinated and they were above 82 years old (6). In an observed study in Turkey in which the subjects were vaccinated against influenza, an increase in the antibody titre in the vaccinated group was observed (7). In a study in Norway, 19 subjects were vaccinated against influenza and an increase in the levels of antibody serum was observed in all the subjects (8). This study was designed in order to investigate the changes in the levels of antibody serum in the vaccinated subjects as compared to the unvaccinated ones and to specify the ratio of the increase in the antibody titre up to the level of prevention.
In this descriptive analytical research, 196 subjects were vaccinated against influenza by the vaccine "influ vac 2005/2006" which is made in Netherlands.The vaccine included 45 micrograms of Haemaglotination and Noraminidaz proteins and was extracted from the following viruses. After 7 weeks, they took transfusions of 5 milititres and their serum were collected and preserved under 20 ˚C until the experiment was carried out.
The Vaccine Virus Included
1-A/California/7/2/2004(H3N2)-Like strain (A/New York/55/2004 NYMC X-157)
2-A/New Caledonia/20/99 (H1N1)-Like strain (A/New Caledonia/20/99 IVR-116)
3-B/Shanghai/361/2002-Like strain (B/Jiangsu/10/2003)
200 subjects who were as old as the vaccinated subjects were selected from blood donor samples and the serum was prepared. At the time of getting the sample, 196 subjects filled out the information collection from which demographic information was obtained. All of the vaccinated subjects and the control group were tested by the Haemaglutintion inhibition test to determine the anti-influenza antibody levels, by methods which were previously described (9),(10). A titre above 40 units of agglutination was considered by the preventive antibody Haemaglotination inhibition test (11).
The data of the antibody titration in serum and the demographic information was entered into the computer and the mean of the antibody titre of the studied groups (vaccinated and unvaccinated subjects) was compared with appropriate statistical tests such as the T-test. The Chi-Square test was used to investigate the relationship between groups of different ages, genders and the existence of the preventive antibody in the subjects.
In this study, 396 subjects were included. In the case group, the male to female ratio was 0.9 and in the control group it was 0.8. The mean age of the vaccinated group was 52.2 Â± 11 years and in the control group it was 48.6 Â± 5.1 years.
Preventive levels of antibodies against influenza was found in 115 (58.7%) out of the 196 vaccinated subjects and in the control group, it was found in 15 subjests (7.5%).
Immunity levels against the influenza virus in the vaccinated subjects and controls according to the age groups is shown in (Table/Fig 1).
The mean antibody titre in the vaccinated and control groups were compared by the T-test, which showed a significant difference them(CI=95% :102.91-144.22; P value=0.000) (Table/Fig 2).
The comparison between the mean antibody titre between the two genders in the vaccinated group didn't show a significant difference by the T-test.
In this study, it was shown that the vaccine was efficient in the vaccinated group and moreover, the existence of these levels of the preventive antibody in 7.5% of the control group showed the circulation of the vaccine viruses among the Gorgan population; especially in one percent of these people, an antibody titre above 512 units of Haemaglutination was found.
A study in America showed that vaccination of subjects under 65 years is preventive in 70 to 90% of the cases and doesn't have any similarities to the results of our study, but for people above 65 years, the preventive level was found to be between 30 to 45% (5).
In our study , the preventive level was about 58.1% in the subjects between 60-80 years. A study in Turkey showed that in vaccinated subjects, the increase in the anti-influenza antibody titre was significant as compared to the control group and is similar to the results of our study (5).
The result of a study in Norway has shown an increase in the anti-influenza antibody titre in all vaccinated subjects (8).
In our study, this level included 58.7% of the vaccinated subjects, for which the reason might be the environmental and background factors involved in the vaccinated subjects. Another study has also reported antibody levels of 72%, which doesn't have any similarities to our study (12).
A study carried out in France reported a changing level of antibody titre in the vaccinated subjects to 7.4% (13).
A study carried out in Iran on 32370 Hajis, out of which 3465 of them were vaccinated with the influenza vaccine, prevented them from getting influenza like diseases in 52% of the cases as compared to the unvaccinated group (14).
This is similar to the results of our study. But these results depend on the conditions of choosing the samples, techniques for searching for the antibodies and underlying factors of the vaccinated subjects, environmental factors and especially, different age ranges of the subjects under investigation.
The mean antibody titre in the vaccinated subjects was 143.4 with an SE equal to 10.86 and in the control group, it was 18.34 with an SE equal to 3.2, that were statistically significantly different and these are similar to the results of the study which was carried out in Turkey (7).
One of the limitations of the research was the lack of measurement of the levels of the antibody titre against each specific injected vaccine viruses.
Finally, according to the results of the study, it is recommended that in the regions or countries where influenza is epidemic, vaccination against the influenza virus must be done, which is preventive in more than 50% of these subjects and prevent them from severe influenza and the side effects resulting from it.
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