Introduction. The seroprevalence study was performed in Vojvodina during May
and June 2010 in order to asses the effects of the 2009 pandemic influenza
A(H1N1)v epidemic on herd immunity. It was a part of the Serbian Ministry of
Health funded nationwide study. Objective. Prevalence of antibodies against
2009 pandemic influenza A(H1N1)v was determined in a 1% sample of the
population monitored for influenza-like illness and acute respiratory
infections in Vojvodina through sentinel surveillance system. Methods. The
study sample involved a total of 1004 inhabitants of Vojvodina. The control
group consisted of randomly selected and age-adjusted 1054 sera collected in
the pre-pandemic period. Sera were tested by the reaction of hemagglutination
inhibition using influenza A/California/7/2009 (H1N1) antigen in dilution
from 1:8 to 1:256. Antibody titers ?1:32 and ?1:8 were considered protective
and diagnostic, respectively. Results. The differences between control and
study sera in all age groups were significant for both diagnostic ?1/8 and
protective titres ?1/32 of hemagglutination inhibition antibodies (chi square
test, p<0.001). The highest percentage of seropositive subjects was
registered in the age group 15-19 years followed by children aged 5-14 years.
Both diagnostic and protective titres were about twice higher in the
vaccinated as compared to the non-vaccinated group. There were no
statistically significant differences in seroprevalence between seven
districts of Vojvodina. Conclusion. The 2009 pandemic influenza A(H1N1)v
epidemic significantly influenced the herd immunity in our population
regardless of low immunization coverage with highest immunity levels in
adolescents aged 15-19 years and with similar herd immunity levels in all the
regions in the province six months after the outbreak.
A seroprevalence study of Covid 19 antibody after 1st wave of the pandemic in South Andaman district, India
