Background. A systematic literature review was conducted to summarize the mortality (overall and by disease severity factors) of US infants and children aged <5 years with respiratory syncytial virus (RSV) or all-cause bronchiolitis (ACB).

Methods. Comprehensive, systematic literature searches were conducted; articles were screened using prespecified eligibility criteria. A standard risk of bias tool was used to evaluate studies. Mortality was extracted as the rate per 100 000 or the case fatality ratio (CFR; proportion of deaths among RSV/ACB cases).

Results. Among 42 included studies, 36 evaluated inpatient deaths; 10 used nationally representative populations updated through 2013, and only 2 included late-preterm/full-term otherwise healthy infants and children. The RSV/ACB definition varied across studies (multiple International Classification of Diseases [ICD] codes; laboratory confirmation); no study reported systematic testing for RSV. No studies reported RSV mortality rates, while 3 studies provided ACB mortality rates (0.57–9.4 per100 000). CFRs ranged from 0% to 1.7% for RSV (n=15) and from 0% to 0.17% for ACB (n=6); higher CFRs were reported among premature, intensive care unit-admitted, and publicly insured infants and children.

Conclusions. RSV mortality reported among US infants and children is variable. Current, nationally representative estimates are needed for otherwise healthy, late-preterm to full-term infants and children.