Vaccines to combat a virus that can lead to fatal lung infections are urgently needed to help prevent child deaths worldwide, research suggests.
Experts report that more than 115,000 children under five are dying each year from complications associated with the infection, called Respiratory Syncytial Virus (RSV).
Almost half of those who die in hospital are younger than six months old and more than 99 per cent of deaths occur in developing countries, the study estimates. Half of the RSV deaths in these countries occur outwith hospital.
Five countries -- India, China, Nigeria, Pakistan and Indonesia -- account for half of the estimated cases of RSV worldwide. Researchers say more data are needed from Africa and South Asia, where the number of RSV infections may be even higher.
Their findings highlight the pressing need for affordable treatments and vaccines as a priority.
The team led by the University of Edinburgh analysed data from 329 studies of RSV infections worldwide. Their estimates indicate there are more than 33 million cases of RSV infection in children under five each year worldwide.
Around three million are admitted to hospital each year with the virus, which causes breathing difficulties and wheezing.
The study is part of an ongoing initiative to provide the most comprehensive assessment of the global burden of RSV infections to date.
RSV is a common and highly contagious virus that infects the respiratory tract of most children before their second birthday. For most babies and young children, it causes nothing more than symptoms of a cold. In some cases, however, it can lead to severe lung complications such as pneumonia or bronchiolitis.
The study was conducted by the RSV Global Epidemiology Network, which includes researchers from 78 institutions and 35 countries worldwide. It is published in The Lancet and was funded by the Bill & Melinda Gates Foundation.
Lead researcher Professor Harish Nair, of the University of Edinburgh's Usher Institute, said: "We are at an opportune time to step up efforts to prevent RSV infection in young children. With more than 60 candidate vaccines in clinical development, it is likely that an RSV vaccine will be available in the next 5-7 years. Our findings will provide better evidence to inform global funding priorities to accelerate vaccine development. It will assist policy makers and experts prepare for early introduction of this vaccine in developing countries."
Professor Nair is coordinating a €29m grant to establish the RSV Consortium in Europe (RESCEU), which aims to address several of the research gaps highlighted in this study. The five-year project is funded by the Innovative Medicines Initiative -- a joint undertaking between the European Union and the pharmaceutical industry association EFPIA.