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. 2011 Mar 18;6(3):e17995.
doi: 10.1371/journal.pone.0017995.

Seroprevalence of pandemic (H1N1) 2009 in pregnant women in China: an observational study

Xiang Huo  1 , Xian Qi, Fenyang Tang, Rongqiang Zu, Liang Li, Bin Wu, Yuanfang Qin, Hong Ji, Jianguang Fu, Shenjiao Wang, Hua Tian, Zhibin Hu, Haitao Yang, Minghao Zhou, Hua Wang, Fengcai Zhu
Affiliations

Seroprevalence of pandemic (H1N1) 2009 in pregnant women in China: an observational study

Xiang Huo et al. PLoS One. .

Abstract

Background: We investigated the seropositive rates and persistence of antibody against pandemic (H1N1) 2009 virus (pH1N1) in pregnant women and voluntary blood donors after the second wave of the pandemic in Nanjing, China.

Methodology/principal findings: Serum samples of unvaccinated pregnant women (n = 720) and voluntary blood donors (n = 320) were collected after the second wave of 2009 pandemic in Nanjing. All samples were tested against pH1N1 strain (A/California/7/2009) with hemagglutination inhibition assay. A significant decline in seropositive rates, from above 50% to about 20%, was observed in pregnant women and voluntary blood donors fifteen weeks after the second wave of the pandemic. A quarter of the samples were tested against a seasonal H1N1 strain (A/Brisbane/59/2007). The antibody titers against pH1N1 strain were found to correlate positively with those against seasonal H1N1 strain. The correlation was modest but statistically significant.

Conclusions and significance: The high seropositive rates in both pregnant women and voluntary blood donors suggested that the pH1N1 virus had widely spread in these two populations. Immunity derived from natural infection seemed not to be persistent well.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing intersts exist.

Figures

Figure 1
Figure 1. Sampling times and epidemic curve.
Sampling times of serologic survey (Jan 1–Mar 28, 2010) shown relative to epidemic curve of pH1N1 cases and percent of ILI (influenza-like illness, ILI %) accounted for out-patient and emergency cases.
Figure 2
Figure 2. Seroprevelance in pregnant women and voluntary blood donors against pH1N1.
Seropositive rates (HAI≥1∶40) of antibodies against pH1N1 in pregnant women and voluntary blood donors at the 4 sampling times after the second wave of pandemic in Nanjing, China.
See this image and copyright information in PMC

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