Anti-Influenza Antibody Level in Mother-Infant Pairs Depending on Trimester of Vaccination of Pregnant Women Using Immunoadjuvant Vaccine

Introduction: Anti-influenza vaccination of pregnant women using a subunit vaccine is an effective method to prevent pregnancy complications and fetal disorders. The efficacy of immunoadjuvant vaccines, as well as the production of IgG antibodies depending on the vaccination trimester requires further investigation. Materials and Methods: 48 mothers were vaccinated against influenza in the II and III trimesters. Grippol plus vaccine was used. Each dose of the vaccine contains antigens of A and B strains and adjuvant Polyoxidonium 500 μg. Hemagluttinine-inhibiting antibodies level (HIAb) were evaluated in sera of mothers and babies at different time points after vaccination using a standard reaction of hemagglutination inhibition, in accordance with criteria developed by the committee for proprietary medicinal products (CPMP). Results: Within 1 month after vaccination, the seroprotection rate against all influenza strains was above the threshold level of 140 in more than 70% of pregnant women. After delivery, the seroprotection level in the group vaccinated in the III trimester was similar for A/California/7/2009/H1N1/v and А/H3N2 strains, and differed for B strain. The percentage of infants with seroprotection was 55.5%-59.3%, while in their mothers, the respective value was 74.1%-81.5% (p<0.05). Within 3 months, the number of infants with seroprotection against influenza strains in mother-infant pairs was decreased: A/California/7/2009/H1N1/v, А/H3N2, B. In infants and the seroprotection level disappeared completely by 6 months. The time of vaccination of pregnant women had no effect on these parameters. In mothers, the protective levels against vaccine strains were found in 46.2%-65.4% of cases after delivery. Conclusion: Vaccination of pregnant women in the II and III trimesters using Grippol plus results in production of antibodies at levels complying with CPMP criteria. No difference in production and transplacental transfer of IgG antibodies against influenza was found in mother-infant pairs vaccinated in different trimesters of pregnancy.