Respiratory Syncytial Virus

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 and 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 5 years.Respiratory Syncytial Virus (RSV) is the most common virus identified in young children with lower respiratory infections. Previous estimates suggested 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. RSV was associated with 22% of all episodes of severe lower respiratory infections and caused between 55,000-199,000 deaths in children under 5 years.

Since then there have been many new studies to collect more data on RSV, particularly in developing countries. There has also been progress in the development of possible RSV vaccines. The WHO Vaccine Advisory Committee highlighted RSV as the most likely “big new vaccine area”, and a vaccine may be available in the next 5-10 years. An updated estimate of the RSV disease burden in 2015has been conducted by a collaborative team of researchers. They recently published their findings in The Lancet.

Studies published between January 1995 and December 2016 and unpublished data from 76 high-quality population-based studies were reviewed to estimate the global incidence and hospital admission rate of RSV-associated lower respiratory infections in children under 5 years for 2015, and also to estimate the in-hospital and overall mortality rates. The data was further segmented by age-group and World Bank income regions, to look at the incidence and mortality in particular populations.

A total of 329 studies were reviewed – 291 of which were not included in previous estimates, and 23% of the included data were from high-quality unpublished sources.After careful review of the data and statistical modelling it was estimated that in 2015 globally, 33.1 million episodes of RSV-ALRI resulted in about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 5 years. In children younger than 6 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. The incidence and mortality varied widely from year to year in each population studied.

The researchers concluded that RSV is a common cause of lower respiratory infections and a major cause of hospital admissions in young children. There are more than 60 possible RSV vaccines in development, some targeting pregnant women and others newborns or infants. These updated estimates of the global incidence of RSV will provide important additional information for directing vaccination development and implementation policy.

Written by Julie McShane, Medical Writer


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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