Background: There are claims that immunisations cause sudden infant death syndrome (SIDS), but some studies have found either no association or that they are associated with a reduced risk of SIDS.
Aims: To conduct a meta-analysis examining the relationship between immunisation and SIDS.
Methods: Nine case-controls studies were identified examining this association, of which four adjusted for potential confounders.
Results: The summary odds ratio (OR) in the univariate analysis suggested that immunisations were protective, but the presence of heterogeneity makes it difficult to combine these studies. The summary OR for the studies reporting multivariate ORs was 0.54 (95% CI=0.39-0.76) with no evidence of heterogeneity.
Conclusions: Immunisations are associated with a halving of the risk of SIDS. There are biological reasons why this association may be causal, but other factors, such as the healthy vaccinee effect, may be important. Immunisations should be part of the SIDS prevention campaigns.