A survey of levels of antibodies against influenza viruses in the population of Wuxi City / 中华实验和临床病毒学杂志

<p><b>OBJECTIVE</b>To investigate levels of antibodies against type A and type C influenza viruses and those against the 2009 H1N1 influenza A virus (before and after the 2009 H1N1 pandemic) among residents in Wuxi. To compare levels of antibodies against the 2009 H1N1 influenza virus (one year after the pandemic) in the unvaccinated population with those in the population who received vaccine.</p><p><b>METHODS</b>Serum samples were collected from subjects (aged 1-60 years) during September 2008 to May 2009, and during September 2010 to January 2011. Also collected were serum samples from adults who had received vaccines for pandemic (H1N1) 2009 for one year. Antibody response to influenza viruses was measured using hemagglutination inhibition (HI) assay. Seropositivity rate, seroprotection rate and geometric mean titer (GMT) were compared for each age group during different periods.</p><p><b>RESULTS</b>Before the outbreak of the 2009 H1N1 pandemic, seropositivity rate, seroprotection rate and GMT among the study subjects in were 2.86% (4/140), 0.71% (1/140) and 5.23, respectively. One year after the outbreak, seropositivity rate, seroprotection rate and GMT among the study subjects were 66.33%, 37.76% and 19.17, respectively. Among them, adult subjects showed 50.00% seropositivity rate, 19.44% seroprotection rate and 13.09 GMT, while adult subjects who had received vaccine for one year showed 61.36% seropositivity rate, 22.73% seroprotection rate and 14.14 GMT. No significant difference was observed between these two populations (P > 0.05 for all three indexes). Furthermore, before the outbreak of the 2009 H1N1 pandemic, levels of antibodies against seasonal influenza viruses among the study subjects were as follows: for H1N1 virus, seropositivity rate, seroprotection rate and GMT were 55.00%, 35.00% and 16.90, respectively; for H3N2 virus, seropositivity rate, seroprotection rate and GMT were 86.40%, 84.30% and 58.56, respectively.</p><p><b>CONCLUSION</b>One year after the 2009 H1N1 influenza A virus had spread to Wuxi, the population levels of antibodies against this virus have approached those against seasonal influenza viruses, as reflected by seropositivity rates, seroproection rates and GMT. Moreover, considerable levels of antibodies against seasonal influenza viruses were observed in populations, indicating no seasonal influenza outbreak would occur recently.</p>

Study on the prevalence rate and immunity of hepatitis B virus infection among urban adults aged over 20 years in Wuxi, Jiangsu province / 中华流行病学杂志

<p><b>OBJECTIVE</b>To study the relationship on the prevalence rate of hepatitis B virus (HBV) infection and hepatitis B vaccination in urban citizens aged over 20 years old which would led to the development of strategies on HBV control.</p><p><b>METHODS</b>A total of 3744 subjects from general population were randomly selected in this study. Both ELISA and radio immunoassay were used to test five items of HBV infection, including HBsAg, anti-HBs, HBeAg, anti-HBe and anti-HBc.</p><p><b>RESULTS</b>The overall standardized infection rate of HBV was 51.7%, and HBsAg, anti-HBs, HBeAg, anti-HBe and anti-HBc were 4.5%, 48.5%, 0.3%, 3.5% and 51.4%, respectively. The two lowest HBsAg positive rates were found in the groups under 30 years old (2.9%) and students (2.6%). Anti-HBc rate among men was significantly higher than seen in women (P < 0.05), and showing a trend of increase with age (chi2 for trend = 256.2, P < 0.001). The standardized rates of HB vaccination in this population was 17.6% and decreasing rapidly with age (P < 0.05). People who had been vaccinated had both lower rates of HBsAg and HBV infection but higher rate of anti-HBs than those who had not (P < 0.05).</p><p><b>CONCLUSION</b>HB vaccination in adults showed a reducing rate of HBV infection in the general population. Together with the enhancement of expanded program on immunization towards HB vaccination in neonates, much attention should be paid to HB vaccination in adults.</p>