Do vaccines cause SIDS (sudden infant death)?
Here is what the checked sources say. Each title links to the original.
Vaccines and Sudden Infant Death Syndrome (SIDS)
CHOP explains why some SIDS deaths happen soon after a shot by coincidence. Using two figures, about 90% of infants vaccinated and about 1,600 SIDS deaths a year, CHOP gives a rough statistical expectation of about 50 SIDS deaths a year within 24 hours of a vaccine by chance; the page does not show the full calculation. CHOP says SIDS incidence is the same in vaccinated and unvaccinated babies. SIDS fell from about 5,000 to 1,600 yearly, credited to the Back to Sleep campaign. Reviewed February 2025.
Do immunisations reduce the risk for SIDS? A meta-analysis
This meta-analysis pooled nine case-control studies of immunization and SIDS. In the four studies that adjusted for other risk factors, vaccinated infants had about half the odds of SIDS (summary odds ratio 0.54, 95% CI 0.39 to 0.76). The authors say this could be partly causal, but other factors such as the "healthy vaccinee effect," where healthier babies are more likely to be vaccinated on time, may matter. So it is an association, not proof that vaccines protect; it found no link to more SIDS.
Sudden unexpected deaths and vaccinations during the first two years of life in Italy: a case series study
Followed about 3 million vaccinated Italian infants (1999 to 2004) after a German report raised concern about a six-in-one (hexavalent) vaccine. The outcome was sudden unexpected death at 1 to 23 months, from death certificates. Of 604 such deaths, 244 had received a vaccine. Risk was higher in days 0 to 7 after the first hexavalent dose (relative risk 2.0, 95% CI 1.2 to 3.5), with no increase after doses 2 and 3. The authors suggest this may be partly residual confounding by age; the cause was not established.
Non-immunization associated with increased risk of sudden unexpected death in infancy: A national case-control study
A French national case-control study from 2015 to 2017 compared 91 infants under one year who died of sudden unexpected death in infancy (a broader category than SIDS) with 182 matched infants. 22% of the infants who died were unvaccinated, versus 12% of the comparison infants. After adjusting for other factors, being unvaccinated was linked to about twice the odds (adjusted odds ratio 2.01, 95% CI 1.01 to 3.98). It is a small observational study, so the estimate is imprecise and shows an association, not that vaccination itself prevented deaths.
Do Vaccines Cause Sudden Infant Death Syndrome (SIDS)?
Johns Hopkins' Institute for Vaccine Safety concludes DTP and hepatitis B vaccines do not cause SIDS, and other routine US vaccines have not been shown to. A 2003 Institute of Medicine review found the evidence favors rejecting a causal link between DTP, or multiple vaccines at once, and SIDS. No increased SIDS risk was found in 129,834 US children after DTP, and a Vaccine Safety Datalink study of over 350,000 births found no link between the hepatitis B birth dose and neonatal death, a broader outcome. A reanalysis of three studies found neither raised nor lowered risk.