RSV vaccines

Based on the latest available global modelled estimates for 2019, about 33 million episodes of Respiratory Syncytial Virus (RSV)-induced acute lower respiratory infections (ALRI) occurred in children aged under 5 years of age; one in five episodes occur in children aged 0-6 months.^{Go to footnote 11}

By two years of age almost all children will have been infected with RSV, with approximately 25-33% developing ALRI. RSV infections recur throughout life, but disease severity is lower in older children and healthy young adults and begins to rise again among elderly persons (e.g., over 65 years of age).^{Go to footnote 22, Go to footnote 33}
A systematic review and meta-analysis from low- and middle-income countries (LMICs) estimated that 26.2% of children aged under 5 years hospitalized with ALRI were RSV-positive. This ranged from 18.9% among children 6– < 60 months to 41.3% among children 0– < 6 months.^{Go to footnote 44}
Another systematic review of the age distribution of RSV disease in children aged under five years in LMICs showed that the mode (peak) age was three weeks for non-facility deaths, four weeks for facility deaths, seven weeks for ICU admissions, 17 weeks for inpatient admissions, 10 weeks for emergency room visits, 28 weeks for outpatient or clinic visits, and 22 weeks for community cases.^{Go to footnote 55} Over a half of ICU admissions and deaths and over a third of emergency room visits and hospitalizations were in infants aged below six months.

Most pooled LMIC estimates rely on pre-COVID datasets, so post-pandemic seasonality changes are not captured.

RSV strains are grouped within a single serotype but are separated into two subgroups: RSV-A and RSV-B and both can cause severe disease. Both subgroups co-circulate during an RSV season; however, the dominating subgroup is unpredictable and varies across annual outbreaks.^{Go to footnote 66, Go to footnote 77}

In children aged under 5 years, an estimated 101 400 deaths occurred in 2019; 97% of all deaths were estimated to have occurred in LMICs. Of the total deaths, 45 700 were estimated to have occurred in infants aged below six months ^{Go to footnote 88, Go to footnote 99}

The estimated case fatality ratio (CFR) in hospitalized children aged 0 - 60 months is 0.1% in high-income countries (HICs), 0.6%–0.8% in LMICs, and 1.4% in low-income countries (LICs). 

Community mortality studies show that a high and unmeasured burden of RSV deaths in children in LMICs occur at home; in these settings, it is estimated that 4 deaths occur in the community for every 1 in-hospital death.^{Go to footnote 1010}

Seasonal epidemics occur every year in the general population in most, but not all, locations globally. Nosocomial outbreaks have been reported in several health care settings, including paediatric and neonatal intensive care units, adult stem cell transplant units, and adult haematology and oncology units in LMICs. RSV outbreaks have also been reported among older adults in long-term care facilities. RSV is not a virus of pandemic potential.^{Go to footnote 1111}

Currently there is no global or regional elimination or control goal for diseases caused by RSV.