title: Seroprevalence of pandemic (H1N1) 2009 in pregnant women in China: an observational study.
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.
  
  
  RESULTS
  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
  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.
authors: Jiangsu Provincial Center for Disease Prevention and Control, Nanjing, China.
authors: Xiang
authors: X
authors: Huo
authors: Xian
authors: X
authors: Qi
authors: Fenyang
authors: F
authors: Tang
authors: Rongqiang
authors: R
authors: Zu
authors: Liang
authors: L
authors: Li
authors: Bin
authors: B
authors: Wu
authors: Yuanfang
authors: Y
authors: Qin
authors: Hong
authors: H
authors: Ji
authors: Jianguang
authors: J
authors: Fu
authors: Shenjiao
authors: S
authors: Wang
authors: Hua
authors: H
authors: Tian
authors: Zhibin
authors: Z
authors: Hu
authors: Haitao
authors: H
authors: Yang
authors: Minghao
authors: M
authors: Zhou
authors: Hua
authors: H
authors: Wang
authors: Fengcai
authors: F
authors: Zhu
mesh_terms: D000328:Adult; D000914:Antibodies, Viral / Q000097:blood; D001782:Blood Donors; D002681:China; D005260:Female; D005865:Gestational Age; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007251:Influenza, Human / Q000097:blood / Q000453:epidemiology* / Q000821:virology*; D058873:Pandemics / Q000706:statistics & numerical data*; D011247:Pregnancy; D037841:Pregnant People; D016036:Seroepidemiologic Studies; D013997:Time Factors
chemical_list: D000914:Antibodies, Viral