Primary prevention
Vaccines
Until 2022 there was no vaccine available for the prevention of respiratory syncytial virus (RSV); however, since 2023 numerous vaccines have become available.
Recombinant RSV vaccine (Abrysvo®)
A bivalent recombinant RSV prefusion F (RSVpreF) protein-based vaccine.
Approved in the US and Europe for the active immunisation of adults ≥18 years of age for the prevention of lower respiratory tract disease caused by RSV. In the US, the vaccine is only approved for people 18-59 years of age who are at increased risk for lower respiratory tract disease caused by RSV.
Approved in the US and Europe for the active immunisation of pregnant women (at 32-36 weeks’ gestation in the US, and 24-36 weeks’ gestation in Europe) for the prevention of lower respiratory tract disease caused by RSV in infants from birth to age 6 months.
Recombinant adjuvanted RSV vaccine (Arexvy®)
A recombinant RSV-specific antigen glycoprotein F stabilised in the prefusion conformation (RSVPreF3), combined with the AS01E adjuvant system.
Approved in the US for the active immunisation of adults ≥60 years of age for the prevention of lower respiratory tract disease caused by RSV. It is also approved in the US for adults 50-59 years of age who are at increased risk for lower respiratory tract disease caused by RSV. In Europe, it is approved for all adults aged ≥18 years.
mRNA RSV vaccine (Mresvia®)
Contains an mRNA sequence that encodes RSV glycoprotein F stabilised in the prefusion conformation.
Approved in the US and Europe for the active immunisation of adults ≥60 years of age for the prevention of lower respiratory tract disease caused by RSV. It is also approved in the US for adults 18-59 years of age who are at increased risk for lower respiratory tract disease caused by RSV.
It should be noted that licensing has been rapidly changing and local drug information sources should be consulted for current indications.
RSV vaccination is recommended in specific groups of people:
Single-dose vaccination with any Food and Drug Administration (FDA) approved vaccine is recommended by the Center for Disease Control and Prevention's Advisory Committee on Immunization Practices (ACIP) for all adults ≥75 years of age , and for adults 50-74 years of age with an increased risk for severe RSV disease.[59][60]
In the US, Abrysvo® is recommended for use in pregnant women between 32 and 36 weeks' gestation using seasonal administration (i.e., during September through the end of January in most of the continental US) to provide passive protection against lower respiratory tract disease caused by RSV in infants from birth through to age 6 months.[61][62]
Immunisation schedules may vary and local immunisation schedules should be consulted for more information. In the UK, pregnant women are offered RSV vaccination from 28 weeks’ gestation.[63]
Advice on revaccination for subsequent pregnancies may vary. In the US, the CDC does not currently recommend another dose of RSV vaccine during subsequent pregnancies; however, in the UK the Health Security Agency recommends offering the RSV vaccine during each pregnancy.[64] Gov.UK. UKHSA: a guide to RSV vaccination for pregnant women Opens in new window
In large, randomised, controlled trials in adults aged ≥60 years, recombinant RSV vaccines provided up to 70% efficacy in preventing RSV infection and up to 90% efficacy against severe disease, when given as a single dose prior to RSV season, with good safety profiles.[65][66] Further data about the possible need for annual repeat dosing are not yet available.
When pregnant women between 24 and 36 weeks' gestation were administered one dose of the recombinant RSVpreF vaccine (Abrysvo®), the efficacy for prevention of RSV infection in their infants up to 6 months of age was 50%, and for prevention of severe RSV disease in infants up to 6 months of age was almost 70% compared to infants of mothers who received the placebo. Somewhat higher rates of protection against both infection and severe disease were seen in the first 3 months of life in the infants of vaccinated mothers.[67] A 2024 systematic review including six RCTs (25 study reports) comparing RSV vaccination with placebo in 17,991 pregnant women concluded that RSV vaccination during pregnancy reduces RSV‐related hospitalisations in infants and has little or no effect on the risk of birth defects.[68]
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Data from the phase 3 ConquerRSV clinical trial, involving 35,541 adults aged ≥60 years in 22 countries, showed a vaccine efficacy for the mRNA RSV vaccine of 83.7% against RSV-associated lower respiratory tract disease with at least two signs or symptoms and 82.4% against the disease with at least three signs or symptoms over a median follow-up of 3.7 months.[69]
Recombinant RSV vaccines have been associated with a small increased risk of Guillain-Barre syndrome (GBS) particularly in older adults ≥60 years of age, in one postmarketing observational study. The increased risk was reported during the 42 days following vaccination.There is currently no evidence of an increased risk of GBS in pregnant women, or with use of the mRNA vaccine.[70][71]
Immunoprophylaxis (passive immunisation)
Nirsevimab, clesrovimab, and palivizumab are monoclonal antibodies that are directed at targets on the RSV F protein and are approved for RSV immunoprophylaxis in infants and children. Nirsevimab is a monoclonal antibody engineered to bind to the prefusion RSV F protein and with an Fc region engineered to prolong its half-life. The changes improve the drug’s efficacy (with early studies showing that the risk of hospitalisation for RSV is decreased by up to 80% as compared to about a 50% decrease in risk of hospitalisation with palivizumab use) and give it the advantage of only requiring a single intramuscular dose (compared to 5 doses with palivizumab).[72][73] Clesrovimab has a similar half-life to nirsevimab and also only requires a single intramuscular dose. A single dose of nirsevimab or clesrovimab provides protection for approximately 5 months. None of these drugs are indicated for treating active RSV infection.
Nirsevimab
Nirsevimab is a long-acting RSV F protein-directed fusion inhibitor monoclonal antibody indicated for the prevention of RSV lower respiratory tract disease in paediatric patients. In the US, it is approved for children up to the age of 19 months. In Europe, it is approved for children up to the age of 24 months. Nirsevimab has an extended half-life, and is intended to protect infants for an entire RSV season with a single intramuscular dose.[74]
Recommendations for the use of nirsevimab for an infant’s first RSV season are dependent on whether the infant’s birthing parent received the RSV vaccine during pregnancy and the timing of administration of that vaccine (if given) relative to birth.[75]
The American Academy of Pediatrics (AAP) and ACIP recommend a single dose of nirsevimab for:[75][76][77]
All infants <8 months of age born during or entering their first RSV season whose mother did not receive the RSVpreF vaccine, whose mother’s vaccine status is unknown, or who were born less than 14 days after their mother’s RSVpreF vaccination.
Infants and children 8-19 months of age who are at increased risk of severe disease and entering their second RSV season regardless of mother’s prior immunisation status, including infants and children:
with chronic lung disease of prematurity requiring ongoing medical therapies within 6 months of the onset of the RSV season;
with severe immunodeficiencies;
with cystic fibrosis and severe lung disease (prior hospitalisation for pulmonary exacerbation, persistent chest radiographic abnormalities) or weight-for-length <10th percentile; or
who are Indigenous people (American Indian and Alaska Natives).
The APP also recommends nirsevimab in the following instances in which both forms of protection (passive immunoprophylaxis and active maternal vaccination) might be considered:[78]
Vaccinated parent who might not have mounted an adequate immune response to vaccination (i.e., because of an immunodeficiency) or have conditions associated with reduced transplacental antibody transfer (like HIV infection).
Infants who experienced loss of transplacentally acquired antibodies (i.e., after ECMO).
Infants at substantially higher risk for severe disease (e.g., haemodynamically significant congenital heart disease).
In healthy preterm infants, nirsevimab resulted in fewer hospitalisations for RSV-associated lower respiratory tract infections compared with placebo.[72] One phase 3 trial found that a single dose of nirsevimab provided protection against medically attended RSV-associated lower respiratory tract infection when given to healthy late-preterm and term infants before an RSV season.[73] The safety and efficacy of nirsevimab were supported by three clinical trials which found that nirsevimab reduced the risk of RSV lower respiratory tract infection by approximately 70% to 75% relative to placebo.[73][79][80][81] One systematic review of evidence suggests nirsevimab is associated with lower odds of RSV-related hospitalization and all-cause LRTI, though length of hospital stay does not differ.[82]
Clesrovimab
Clesrovimab is another long-acting F protein-directed fusion inhibitor monoclonal antibody indicated for the prevention of RSV lower respiratory tract disease in paediatric patients.
The AAP and ACIP recommend clesrovimab as an alternative to nirsevimab in infants aged <8 months born during or entering their first RSV season whose mother did not receive the RSVpreF vaccine, whose mother’s vaccine status is unknown, or who were born less than 14 days after their mother’s RSVpreF vaccination. It is not recommended in infants and children aged >8 months.[78][83] It has also been approved in the US and Europe for neonates and infants who are born during or entering their first RSV season. Like nirsevimab, clesrovimab has an extended half-life, and is intended to protect infants for an entire RSV season with a single intramuscular dose.
One phase 2b/3 trial found clesrovimab reduced the incidence of medically attended RSV-associated lower respiratory tract infection by 60.4% compared to placebo.[84] The safety and efficacy of clesrovimab was found to be comparable to palivizumab in a further phase 3 clinical trial.[85]
Palivizumab
Palivizumab was the first monoclonal antibody indicated for the prevention of serious lower respiratory tract disease caused by RSV in high-risk infants and children. It is still approved in the US and Europe.
Immunoprophylaxis with palivizumab for infants at high risk reduced hospital admissions by 45% to 55% and was associated with a reduction in all-cause mortality.[86][87] The need for frequent injections and its expense limited its use on a large scale.[88]
It is no longer routinely recommended by the AAP, given the lower cost, easier administration, and likely greater efficacy of other monoclonal antibody treatments.[78]
Secondary prevention
Hand washing in the clinical and non-clinical settings is important.[2] Hand washing and washing of shared toys is important for all family members and close contacts to limit spread of respiratory syncytial virus (RSV) infection.
Patients requiring hospitalisation should be placed in isolation with contact precautions.[8] Proper use of barriers such as gowns, gloves, and masks is effective if large respiratory droplets are present and should be worn when providing care to these patients.[159][160][161][162] An N95 respiratory mask is not required, and is not more effective than a simple surgical mask.[35][99][163] Screening for RSV in suspected patients allows for cohorting and isolation of patients with confirmed infection, limiting further spread of the virus.[99]
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