Post-Pandemic Seroprevalence of 2009 Pandemic Influenza A (H1N1) Virus in Shandong Province, China

Abstract

SUMMARY:The purpose of this study was to understand the geographic extent, risk factors, and attack rate of the 2009 pandemic influenza A (H1N1) virus [A(H1N1)pdm09] infection in Shandong Province, China and to identify the influencing factors. A randomized serological survey of A(H1N1)pdm09 infection was carried out in August and September 2010. A total of 4,549 participants involved in the survey had their antibody levels tested by hemagglutination-inhibition assay. The overall seropositive rate for A(H1N1)pdm09 antibodies was 25.85z. The seropositive rate was 25.89z for the unvaccinated group, with statistically significant differences among individuals of different age groups, occupations, and cities. The highest seropositive rate was observed in young children aged 0-5 years and elderly people aged AE60 years. Multivariate logistic regression revealed that subjects in rural areas had significantly higher odds ratio of A(H1N1)pdm09 seropositivity than those in the capital city. Individuals belonging to all professions, except for teachers, had significantly lower odds ratio of A(H1N1)pdm09 seropositivity compared with children in family care. Our data indicated that almost 26z of the residents in Shandong Province had appropriate antibody titers against A(H1N1)pdm09. This seroepidemiology study provides valuable data for understanding the epidemiology of the 2009 pandemic influenza and for planning future intervention strategies; moreover, it highlights the significance of seroprevelance studies.

Serological Surveillance of the H1N1 and H3N2 Swine Influenza A Virus in Chinese Swine between 2016 and 2021

“…Since shortly after the emergence of pdm/09, the pdm/09 H1N1 subtype was spread to pigs throughout the world [ 30 – 32 ]. The reassortment between the pdm/09 H1N1 virus and endemic IAV-S has occurred frequently [ 8 , 31 ], and IAV-S with surface genes of pdm/09 origin are rarely isolated [ 28 , 31 , 33 , 34 ]. In this study, the positivity rate of the pdm/09 H1N1 subtype was 7.49%, which was lower than that of the EA H1N1 subtype.…”

“…Serum samples from pig workers and residents were positive for pdm/09 H1N1 at a rate of 8.4% and 11.4%, respectively [ 37 ]. Moreover, almost 26% of residents in Shandong Province also carry antibodies against the pdm/09 H1N1 subtype [ 33 , 34 ]. Positivity rates of 19% and 28.7% to the pdm/09 H1N1 subtype were also detected in serum samples from all types of outpatients and pediatric outpatients, respectively [ 38 , 39 ].…”