Background: Pregnant women and infants who get influenza are at increased risk for severe illness. Objective: To evaluate the immunogenicity and transplacental antibody transfer of 2009 pandemic influenza A(H1N1) vaccine administered during pregnancy. Design: Prospective, multicenter, single-group clinical trial. (Clinical Trials.gov registration number: NCT01024400) Setting: Five level-3 perinatal centers in France. Patients: 107 pregnant women between 220/7 and 320/7 weeks of gestation. Intervention: An intramuscular dose of a nonadjuvanted H1N1 vaccine that contained 15 mcg of hemagglutinin. Measurements: Proportion of women with an influenza antibody titer of 1:40 or greater at days 21 and 42 after vaccination, delivery, and 3 months after delivery. Seroconversion rate, fold increase in the geometric mean titer 21 days after vaccination, and proportion of neonates with an antibody titer of 1:40 or greater at birth were also assessed. Results: At baseline, 19% of the women had an antibody titer of 1:40 or greater. At day 21, 98% of the women had an antibody titer of 1:40 or greater, the seroconversion rate was 93%, and the fold increase in geometric mean titer was 67.4. At day 42, delivery, and 3 months after delivery, 98%, 92%, and 90% of the women, respectively, had an antibody titer of 1:40 or greater. Ninety-five percent of the cord serum samples obtained from 88 neonates showed an antibody titer of 1:40 or greater. The median neonate- mother antibody titer ratio was 1.4. Limitations: Only healthy pregnant women were selected. Data on hemagglutination inhibition antibody titers of infants were reported only at birth. Conclusion: A single dose of a nonadjuvanted influenza A(H1N1) vaccine with 15 mcg of hemagglutinin triggered a strong immune response in pregnant women and a high rate of neonatal seroprotection. Primary Funding Source: French National Institute of Health and Medical Research. © 2011 American College of Physicians.
CITATION STYLE
Tsatsaris, V., Capitant, C., Schmitz, T., Chazallon, C., Bulifon, S., Riethmuller, D., … Launay, O. (2011). Maternal Immune Response and Neonatal Seroprotection from a Single Dose of a Monovalent Nonadjuvanted 2009 influenza A(H1N1) vaccine: A single-group trial. Annals of Internal Medicine, 155(11), 733–741. https://doi.org/10.7326/0003-4819-155-11-201112060-00005
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