Respiratory Syncytial Virus (RSV) is a common cause of viral upper respiratory tract infection and often mistaken for the common cold. RSV is a cold weather seasonal virus associated with severe disease and death in two populations with relatively less effective immune systems: infants and older adults. In the last year, several new RSV prevention options have been approved to protect these vulnerable populations from severe RSV. 

RSV Prevention for Older Adults

Older adults with chronic conditions are likely to benefit most from RSV vaccination. The body’s immune system weakens with age and this “immunosenescence” contributes to greater susceptibility to infections, including RSV, and an increased risk of complications.  Additionally, many chronic comorbidities common in older adults also increase the risk of complications from RSV infection.

Two RSV vaccines are available to adults over 60 years of age in the United States: Arexvy and Abrysvo. Both RSV vaccines contain a protein of the respiratory syncytial virus (not mRNA) that induces an immune response and protects against severe infection. In randomized trials, a single dose of either RSV vaccine was moderately-to-highly effective at preventing RSV pneumonia in the RSV season immediately after vaccination. Moderate effectiveness was maintained the following year, suggesting that annual vaccination may not be necessary. 

The RSV vaccine may be co-administered with other vaccines such as seasonal influenza vaccination. However, administering the RSV vaccine with other vaccines has the potential to increase the risk of local or systemic adverse reactions. Data on immunogenicity and safety of co-administering seasonal vaccines together is being collected to guide recommendations going forward.

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RSV Prevention for Infants

There are two ways to protect infants from severe RSV infection and both involve providing infants with antibodies that can fight the virus in collaboration with their own developing immune systems. Anti-RSV antibodies are either shared by the mother after maternal vaccination or provided directly to the infant via an injection.

Maternal RSV vaccination during the third trimester of pregnancy induces immunity in the pregnant individual, whose anti-RSV antibodies are shared with the fetus during pregnancy and can continue to be shared via breastmilk after delivery. The Abrysvo RSV vaccine is recommended for anyone 32-36 weeks pregnant from September through January.

Additionally, there are two monoclonal antibody medications aimed at providing passive immunity against RSV in babies: nirsevimab and palivizumab. Nirsevimab is a new long-acting antibody that requires just one dose, while palivizumab is a five-dose series that has been licensed since 1998.

Passive immunization with nirsevimab is currently recommended for infants up to eight months old who are born during or entering their first RSV season. It is also recommended for infants eight-19 months old at high risk for severe RSV who are entering their second RSV season. Palivizumab should only be used if nirsevimab is not available.

Either maternal vaccination or passive immunization with a monoclonal antibody is sufficient to prevent severe RSV infection in most infants. That is, just one method should be chosen.

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General RSV (and other respiratory infections) Prevention Measures

RSV is a common respiratory disease and general infection prevention measures can help to limit its spread including:

  • Stay home when sick
  • Cover coughs and sneezes
  • Wash hands often and thoroughly
  • Clean frequently touched surfaces
  • Consider wearing a well-fitting facemask or respirator