Are all vaccines safe for the pregnant traveler? A systematic review and metaanalysis.

Pregnant travelers and their offspring are vulnerable to severe outcomes following a wide range of infections. Vaccine preventable diseases can have a particularly severe course in pregnant women, but little is known about the safety of travel vaccines in pregnant women. We performed a systematic review of all published literature concerning the safety of vaccines frequently given to travelers such as yellow fever, MMR (mumps, measles, and rubella), influenza, Tdap (tetanus, diphtheria, and pertussis), meningococcus, hepatitis A and B, rabies, polio, typhoid fever, tick-borne encephalitis, and Japanese encephalitis vaccines. We included case series, cohort studies, and randomized controlled trials (RCTs). For the meta-analysis we included only RCTs that compared the administration of a vaccine to placebo or to no vaccine. Outcome measures included severe systemic adverse events, maternal outcomes related to the course of pregnancy, neonatal outcomes, and local adverse events. We calculated the risk ratio (RR) and its 95% confidence interval (CI) as the summary measure. The safety of influenza vaccine is supported by high-quality evidence. For Tdap vaccine no evidence of any harm was found in the meta-analysis of RCTs. A slight increase in chorioamnionitis rate was reported in three out of twelve observational studies. However, this small possible risk is far outweighed by a much larger benefit in terms of infant morbidity and mortality. Meningococcal vaccines are probably safe during pregnancy, as supported by RCTs comparing meningococcal vaccines to other vaccines. Data from observational studies support the safety of hepatitis A, hepatitis B, and rabies vaccines, as well as that of the live attenuated yellow fever vaccine. We found little or no data about the safety of polio, typhoid, Japanese encephalitis, tick-borne encephalitis and MMR vaccines during pregnancy.