Seroprevalence of influenza A H1N1 and seroconversion of mothers and infants induced by a single dose of monovalent vaccine.
OBJECTIVE
To determine the prevalence of preexisting antibodies against the pandemic 2009 Influenza A (H1N1) virus in pregnant women and to evaluate the seroprotection of the mothers and infants by a single injection of monovalent vaccine during the pandemic.


METHODS
Seropositivity rate of H1N1 among the nonvaccinated were compared with the vaccinated women. A single dose of vaccine, either nonadjuvanted AdimFlu-S or MF59-adjuvanted vaccine, was injected to the voluntarily vaccinated group. Maternal and cord blood sera were collected to evaluate the antibody response of the H1N1 virus. Seropositivity was defined as a hemagglutination inhibition titer to H1N1 (A/Taiwan/126/09) ≥ 1:40.


RESULTS
A total of 210 healthy, singleton, pregnant women were enrolled between January 2010 and May 2010. Seropositivity (≥ 1:40) of maternal hemagglutination inhibition was significantly higher in the vaccinated group (78%) than the nonvaccinated group (9.5%); 41.6% (20/48) of seropositive titers were >1:80. In nine vaccinated cases resulting in negative serum titers (<1:40), the prevalence of negative titer in the women received AdimFlu-S (14.8%, 4/31) was lower (p = 0.025) than those received MF59-adjuvanted vaccine (50%, 5/10).


CONCLUSIONS
Subclinical infection against H1N1 was low in Taiwanese pregnant women in the pandemic 2009. Seropositivity >75% could be achieved in the paired maternal and cord serum samples by a single injection of monovalent H1N1 vaccine.
Department of Anesthesiology, National Taiwan University Hospital, Taipei, Taiwan.
Anne
A
Chao
Yhu-Chering
YC
Huang
Yao-Lung
YL
Chang
Tzu-Hao
TH
Wang
Shuenn-Dyh
SD
Chang
Ting-Shu
TS
Wu
Tsu-Lan
TL
Wu
An-Shine
AS
Chao
D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000914:Antibodies, Viral / Q000097:blood*; D005260:Female; D006385:Hemagglutination Inhibition Tests; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology*; D007252:Influenza Vaccines / Q000008:administration & dosage / Q000276:immunology*; D007251:Influenza, Human / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control*; D008431:Maternal-Fetal Exchange / Q000276:immunology; D009035:Mothers; D011159:Population Surveillance; D011247:Pregnancy; D011446:Prospective Studies; D016036:Seroepidemiologic Studies; D013624:Taiwan
D000276:Adjuvants, Immunologic; D000914:Antibodies, Viral; D007252:Influenza Vaccines
H1N1; infant; influenza A; pregnancy; vaccine