Adverse Events After Measles and Bacillus Calmette-Guérin Vaccinations of Women of Fertile Age in Guinea-Bissau. A Nested Study Within an Open-Label Placebo-Controlled Randomised Trial.

BACKGROUND: Within a randomised controlled trial providing Bacillus Calmette-Guérin, measles vaccine, or placebo to women of fertile age, we aimed to study the risk of adverse events following vaccination. This study addresses the lack of data on adverse reactions in adults, especially women of childbearing age, to inform broader vaccination policies.

METHODS: The trial included HIV-negative, non-pregnant women aged 15 to 35 years, who had given birth to at least one child, and residing in the Bandim Health Project study area in the capital Bissau of Guinea-Bissau. Excluded were individuals who were frail, had serious illnesses like active tuberculosis, or had no prior births. Participants were randomised 1:1:1 to bacillus calmette-guérin, measles vaccine, or placebo. A subset of participants was enrolled into the adverse events study. Adverse events were registered immediately 15 min post-vaccination and at home visits 7, 14, 28 and 90 days after enrolment to register symptoms that could be related to the trial interventions. We compared symptom distributions by randomisation using chi-squared tests.

RESULTS: Of the total 366 women included in the study, 99% (363) were eligible to follow up for adverse events (Placebo, 121; measles vaccine, 121; Bacillus Calmette-Guérin, 121) and 97% (1414/1452) of the planned study contacts were successful, 1.3% (18/1414) of which were mobile phone interviews. The baseline characteristics did not differ between the randomisation groups. There were no immediate reactions within the first 15 min post-vaccination. Seven days after vaccination, there was a tendency for more episodes of headache reported among both the Bacillus Calmette-Guérin and measles vaccine vaccinated participants compared to placebo. We registered 11 medical consultations (placebo: 4, measles vaccine: 5, Bacillus Calmette-Guérin: 2) and no deaths or hospitalisations during 90 days of post-enrolment follow-up.

CONCLUSION: Bacillus Calmette-Guérin and measles vaccine were safe and tolerable for adult women of childbearing age, with few short- and medium-term adverse events.