Respiratory syncytial virus (RSV)
Respiratory syncytial virus (RSV) is the most important cause of viral acute lower respiratory infection (ALRI) in infants and children worldwide and is responsible annually for over 30 million new ALRI episodes, 3.2 million hospital admissions, and nearly 120,000 deaths in children under five years old, usually before six months of age. The virus infects nearly all children at least once by the age of two and is the most common cause of bronchiolitis and infant pneumonia. RSV disease burden is less understood in the developing world, but available data indicate that almost all RSV-related deaths occur in these settings and that the health and economic impacts are substantial. The prevention tool palivizumab (a monoclonal antibody [mAB]) can help prevent RSV disease in high risk infants, but it cannot treat or cure already-serious RSV infection. No vaccine exists today to prevent RSV due to an incomplete understanding of the body’s immune response to the virus, which has challenged and delayed RSV vaccine development efforts. Recent years have seen an increase in vaccine development activity around RSV, including vaccine and new mAB candidates advancing into late-stage development.
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- RSV is the most important cause of ALRI in infants and children worldwide and is responsible for over 30 million new ALRI episodes and nearly 120,000 deaths in children under five years old, usually before six months of age. The elderly are also at risk of severe RSV disease.
- The virus, which belongs to the Paramyxoviridae family, can cause symptoms similar to the common cold, but can also lead to otitis media (middle ear infection), pneumonia, and bronchiolitis (inflammation of the small airways in the lung). Infection with RSV early in life can increase the chances of developing recurrent wheezing and asthma.
- In the industrialized world, RSV is the leading cause of child hospitalizations due to ALRI, with up to 125,000 hospitalizations per year in the United States alone. By the age of two, nearly all children have been infected with RSV at least once.
- Disease burden in low-resource countries is less understood, but available data indicate that the virus is responsible for a high proportion of childhood ALRI in these settings, particularly in the first few months of life. Global estimates indicate that RSV causes more than 25 percent of pediatric respiratory deaths in the first five years of life. RSV can also lead to substantial economic hardship in the developing world where hard-to-reach healthcare, hospital costs, and lost livelihoods make caring for the sick particularly burdensome for caregivers, households, and communities.
- Studies have shown RSV to occur in well-defined seasons during the winter and spring months in countries where the climate is temperate. In tropical climates, data indicate that RSV may increase in prevalence during the rainy season, but these findings are not consistent.
- RSV is transmissible from person to person and can be spread through inhalation of or contact with nasal secretions from an infected individual via droplets containing the virus that are sneezed or coughed into the air.
- Since RSV can survive on many hard surfaces for several hours, frequent hand washing and cleaning of hard surfaces can help reduce or stop the spread of the virus.
- Natural infection with RSV does not provide complete protection against future infection.
- The prevention tool palivizumab can help prevent RSV disease in high risk infants, but it cannot treat or cure RSV infection that is already serious. Availability, cost, and treatment logistics make its use impractical in resource-constrained settings.
- No vaccine exists today to prevent RSV infection due to an incomplete understanding of the body’s immune response to the virus, which has challenged and delayed RSV vaccine development efforts.
- Attempts in the 1960s to develop a formalin-inactivated RSV vaccine candidate were hampered by several factors, including lack of protection against infection in infants and children, and an association with younger children experiencing more severe RSV disease when naturally infected with RSV after having been vaccinated.
- Other types of vaccine approaches are currently in development to combat RSV, including a maternal RSV vaccine now in late-stage development.
- Vaccines for maternal immunization—whereby a woman is vaccinated during pregnancy to increase her immunity and promote the transfer of antibodies to her developing fetus—is an approach being explored to protect infants in the first few months after birth.
- Affordable mABs that can be given to newborns at birth are also in development for the purpose of providing protection in early life.
- Shi T, McAllister DA, O’Brien KL, 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.
- US Centers for Disease Control and Prevention. Respiratory Syncytial Virus Infection.
- World Health Organization. Acute Respiratory Infections (Update September 2009): Respiratory Syncytial Virus and Parainfluenza Viruses.
Page last updated: November 2017.
Photo: PATH/Evelyn Hockstein.