Respiratory Syncytial Virus (RSV)

Respiratory syncytial virus (RSV) is the most common virus causing acute lower respiratory infection in young children. A recent comprehensive review study gives an updated estimate of the worldwide impact of RSV. In addition, it provides key information to direct future vaccine development and implementation policy.

Acute lower respiratory tract infection (ALRI), usually pneumonia or bronchiolitis, is one of the leading causes of illness and death in children under five. Respiratory syncytial virus (RSV) is the most common virus identified in young children with lower respiratory infections. Previous estimates suggest that in 2005 about 33.8 million new episodes of RSV lower respiratory infections occurred worldwide in young children, 10% severe enough to need hospital admission. In addition, RSV was associated with 22% of all episodes of severe lower respiratory infections and caused between 55,000-199,000 deaths in children under five.

RSV developments

The WHO Vaccine Advisory Committee highlighted RSV as the most likely “big new vaccine area”. A vaccine may be available in the next 5-10 years. A total of 329 studies were reviewed, with 291 of which were not included in previous estimates of RSV data. After careful review, it was estimated that in 2015 globally, 33.1 million episodes of RSV-ALRI resulted in about 3.2 million hospital admissions and 59,600 in-hospital deaths in children under five years of age.

In children younger than six months, 1.4 million hospital admissions and 27,300 in-hospital deaths were due to RSV-ALRI.  It was also estimated that the overall RSV-ALRI mortality could be as high as 118,200. However, the incidence and mortality varied widely yearly in each population studied.

RSV is a common cause of lower respiratory infections and a major cause of hospital admissions in young children. In addition, more than 60 possible RSV vaccines are in development. Some of the developing vaccines are targeting pregnant women and others newborns or infants. These estimates of the global incidence of RSV provide essential information for directing vaccination development and implementation policy.


Shi T, McAllister DA, O’Brien K, et al. Global, regional, and national disease burden estimates of acute lower respiratory infections due to respiratory syncytial virus in young children in 2015: A systematic review and modelling study. The Lancet. Published online July 6, 2017.

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