Safety of live attenuated vaccines in immunocompromised individuals and pregnant women: a systematic literature review

Background: Live-attenuated vaccines (LAVs) are typically contraindicated for immunocompromised patients and pregnant women, although the potential benefits of vaccination with LAV in these populations should not be overlooked. This systematic literature review was conducted to evaluate the safety of LAVs in immunocompromised patients and pregnant women. Research design and methods: The searches were conducted across PubMed, Embase, and Cochrane databases. We included studies reporting on safety outcomes of LAV use in immunocompromised patients and pregnant women. A narrative synthesis was employed to present the primary findings. Results: A total of 96 studies were included, reporting outcomes on 18 LAVs, mostly for varicella-zoster, measles-mumps-rubella, and influenza vaccines. Comparative studies revealed minor differences in adverse events (AEs) between immunocompromised LAV recipients and placebo recipients, and between immunocompromised and healthy vaccinated individuals. Severe AEs and fatalities were infrequent, primarily noted in oncology patients in case studies. Twelve studies addressed LAV safety in pregnant women, with no instances of vertical transmission reported, and no conclusive link found between LAVs and serious AEs. Conclusions: LAVs appeared generally safe and well-tolerated for immunocompromised patients and pregnant women. However, evidence is still limited, and more research is needed to address data gaps and support evidence-based decision-making.