Pertussis is resurging worldwide and in Africa alone it is estimated that there are 2.1 million cases and 542,000 deaths from pertussis in infants under 1 year with the highest rates of morbidity and mortality in infants <3 months old, before possible prevention via the infant immunization programme. To protect these most vulnerable infants, immunization with Tdap during pregnancy providing passively transferred antibodies is an increasingly utilised intervention. This is currently recommended to all pregnant women in some high-income countries (e.g. USA, UK and Canada) and is a consideration in low middle-income countries, with policy makers hampered by lack of local data.

Previous studies evaluated the immunogenicity of Tdap administration in immunocompetent pregnant women demonstrating this to be highly effective at reducing disease in young infants <3 months of age. Immunization during pregnancy against pertussis increases pertussis-specific Immunoglobulin G (IgG) antibody levels in the mother, which then cross the placenta and are transferred to the newborn.

Different factors might affect the magnitude of the trans-placental transfer of IgG to the newborn including the mothers’ health status, the concentration of total and vaccine-specific IgG in maternal sera, the integrity of the placenta, the type and timing of vaccine administration to the pregnant women during pregnancy. Of particular concern is maternal HIV infection – there are no data on the immunogenicity of pertussis vaccines in pregnancy in HIV-infected women.

This is a phase II intervention randomised, observer blind, clinical trial of Tdap in pregnancy and wP (Whole-cell Pertussis) vaccine responses in infancy based at Kawempe National Referral Hospital and Kisenyi Health Centre IV Kampala.

The study aims to determine the safety and immunogenicity of Tdap vaccine given in pregnancy to women living with HIV.

The study will take a 2×2 formation, with four groups:

1. HIV-uninfected women, standard of care vaccines in pregnancy;
2. HIV-uninfected women, Tdap vaccine in pregnancy;
3. HIV-infected women, standard of care vaccines in pregnancy;
4. HIV-infected women, Tdap vaccine in pregnancy.

January 2020 – June 2023