Kinetics of Hemagglutination-Inhibiting Antibodies Following Maternal Influenza Vaccination Among Mothers With and Those Without HIV Infection and Their Infants

Abstract

Background. We evaluated the immunogenicity of trivalent inactivated influenza vaccine (IIV3) in pregnant women with and those without human immunodeficiency virus (HIV) infection and the persistence of hemagglutination-inhibiting antibodies in mothers and infants. Methods. Antibodies were measured before vaccination, 1 month after vaccination, at delivery, and at postpartum week 24 in mothers and within 1 week of birth and at 8, 16, and 24 weeks of age in infants. Results. We enrolled 98 HIV-uninfected and 100 HIV-infected pregnant women, including 93% with a CD4⁺ T-cell count of ≥200 cells/µL. Compared with HIV-uninfected women, HIV-infected women had lower seroconversion rates (ranging from 63%–92% vs 36%–40%), lower antibody titers through postpartum week 24, and overlapping antibody half-lives (ranging from 106–121 vs 87–153 days). Infant titers were lower than the maternal titers within 1 week of delivery, regardless of vaccine strain and HIV exposure status. Compared with HIV-unexposed infants, HIV-exposed infants had a similar transplacental influenza virus antibody transfer ratio, lower titers, and a lower frequency of titers ≥1:40 (ranging from 82%–95% vs 43%–79%) at birth and higher antibody half-lives (ranging from 43–45 vs 56–65 days). Conclusions. Compared with HIV-uninfected pregnant women, HIV-infected pregnant women had lower antibody responses and persistence. Compared with HIV-unexposed infants, HIV-exposed infants had lower antibody levels at birth but similar antibody levels after 8 weeks of life. Early IIV3 administration during pregnancy did not decrease antibody titers among infants at birth.