Immunogenicity of tetanus, diphtheria and acellular pertussis vaccination among pregnant women living with and without HIV.

Abstract

Vaccination during pregnancy with tetanus-diphtheria-acellular pertussis (Tdap) vaccine is recommended to protect the young infants against pertussis. There is a paucity of data on immune responses to Tdap in pregnant women living with HIV (PWLWH), and its impact on the protection of their infants has not been described. In an open label phase IV clinical trial in South Africa, we evaluated the immunogenicity and safety of Tdap in PWLWH compared with HIV-uninfected women. Antigen-specific immunoglobulin G (IgG) to pertussis toxoid, filamentous hemagglutinin, pertactin, fimbriae, diphtheria and tetanus were measured by electrochemiluminescence-based multiplex assay. Overall 91 PWLWH and 136 HIV-uninfected pregnant women were enrolled. All PWLWH were on antiretroviral treatment and 94.5% had HIV viral loads <40 copies per millilitre. Antibody levels pre-vaccination were lower among PWLWH compared with HIV-uninfected women for all antigens. At one-month post-vaccination PWLWH compared with HIV-uninfected women had lower fold-increase and antibody concentrations for all epitopes. Also, a lower proportion of PWLWH achieved ≥4-fold increase from pre to post-vaccination for pertussis toxoid and pertactin, or diphtheria IgG levels ≥0.1IU/mL and ≥1IU/mL post-vaccination. Adverse events post-vaccination were similar in PWLWH and HIV-uninfected. Tdap vaccination was safe and immunogenic. PWLHW had, however, attenuated humoral immune responses, which could affect the effectiveness of protecting their infants against pertussis compared with those born to women without HIV. ClinicalTrials.gov identifier: NCT05264662.