Administering flu vaccines to pregnant women during their second and third trimesters results in high seroprotection against all influenza strains for most women and for more than half of their newly born babies, reported Dr. M.P. Kostinov and colleagues at the I.I. Mechnikov Scientific Research Institute of Vaccines and Sera, at Ul’yanovsk State University, Moscow. The study was published in the Journal of Vaccines & Vaccination.
Researchers gave influenza vaccines (the Grippol Plus vaccine) to 27 women in their second trimesters and 21 women in their third trimesters of pregnancy during 2010-2012. Each 0.5-mL dose of the preservative-free vaccine contained antigens of the following strains: A/California/7/2009/H1N1/v-like (5 mcg), A/H3N2/(Victoria)-like (5 mcg), and B/Brisbane-like (5 mcg) flu.
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Within 1 month after vaccination, the seroprotection rate against all influenza strains was above the recommended threshold level of 1:40 in more than 70% of pregnant women. A gradual decrease in the seroprotection rates against all three influenza strains was reported in the postpartum period.
In infants, protective levels of antibodies were detected within 2-3 days of delivery and ranged from 52% to 62% regardless of the trimester when the vaccination was given. Within 3 months, this seroprotection decreased, and within 6 months it disappeared. The mothers’ protective levels against vaccine strains were 46%-65% after delivery.
Read the article in the Journal of Vaccines & Vaccination (Pakhomov et al. J Vaccines Vaccin. 2015,6:5).