Respiratory Syncytial Virus disease morbidity in Australian infants aged 0 to 6 months: A systematic review and evaluation

Background: To appraise and synthesise the evidence of respiratory syncytial virus infection morbidity among Australian aged 0 to 6 months, and to assess the implications for future vaccination strategies. Methods Electronic databases (MEDLINE, EMBASE, Pubmed and Global Health) were searched in April 2023. Full-text articles published between 2000 and 2023 in English language that examined markers of disease morbidity in infants aged up to 6 months in Australia who had laboratory confirmed respiratory syncytial virus infection were eligible for inclusion. From 259 studies screened, 191 qualified for full text review, 175 were excluded based of pre-specified criteria. This review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses and Synthesis without meta-analysis guidelines. Quality of evidence was assessed with Critical Appraisal Skills Programme criteria. Results Sixteen studies from all states and territories in Australia were included. Our findings indicated that infants aged 0 to 6 months had higher respiratory syncytial virus testing, positivity and incidence rates, higher rates of hospitalisation in both general wards and intensive care units, and were more likely to require respiratory support compared to children and adults of all ages. Indigenous infants aged up to 6 months demonstrated higher respiratory syncytial virus incidence and hospitalisation, compared to non-Indigenous infants. Age-related trends persisted in geographic areas with varying respiratory syncytial virus season transmission, and also persisted despite the impact of the SARS-CoV-2 pandemic. Conclusions A significant proportion of Australia’s respiratory syncytial virus-associated morbidity is accounted for by infants aged 0 to 6 months, who are particularly vulnerable to severe disease. Vaccination of women during the latter stages of pregnancy may be a cost efficient way to protect young infants who account for a disproportionate burden of severe respiratory syncytial virus disease.