What is the duration of protection from Respiratory Syncytial Virus (RSV) vaccination?

Duration of Protection from RSV Vaccination

A single dose of RSV vaccine provides protection for at least two RSV seasons in adults aged ≥60 years, with current recommendations not requiring revaccination. 1

Duration by Vaccine Type and Population

Adult RSV Vaccines (≥60 years)

Protection extends through multiple RSV seasons with a single dose:

• RSVPreF3 (Arexvy) maintains efficacy for at least three seasons in adults aged ≥60 years 2
• RSVpreF (Abrysvo) maintains efficacy for at least two seasons in adults aged ≥60 years 2
• Adults who have already received RSV vaccination should not receive another dose at this time 1
• ACIP will evaluate the need for additional RSV vaccine doses in the future and update recommendations as needed 1

Vaccine effectiveness data from real-world studies:

• During two RSV seasons combined, vaccine effectiveness against RSV-associated hospitalization was 58% (95% CI: 45%-68%) 3
• Same-season vaccination showed 69% effectiveness (95% CI: 52%-81%) 3
• Prior-season vaccination showed 48% effectiveness (95% CI: 27%-63%), though this difference was not statistically significant (P = 0.06) 3

Important caveat: Effectiveness was significantly lower in immunocompromised adults (30%; 95% CI: -9% to 55%) compared to immunocompetent adults (67%; 95% CI: 53%-77%; P = 0.02) 3. Adults with cardiovascular disease also showed lower effectiveness (56%) compared to those without (80%; P = 0.03) 3.

Maternal RSV Vaccination (Pregnancy)

Protection for infants is time-limited and wanes after birth:

• Protection conferred through maternal vaccination likely wanes after 3 months, similar to what has been observed with influenza and COVID-19 vaccines given during pregnancy 1
• At least 14 days are required after maternal vaccination for adequate antibody development and transplacental transfer to protect the infant 1, 4
• Maternal RSV-specific antibodies decline rapidly following birth, with a calculated half-life of 79 days (95% CI: 76-81 days) 5
• Despite rapid decline, maternal antibodies provide evidence of protection against severe disease during the first 6-7 months of life 5

Critical timing consideration: The maternal RSV vaccine is given as a single dose between 32 weeks 0 days and 36 weeks 6 days of gestation 4. Additional data are needed to determine whether additional seasonal doses during subsequent pregnancies are indicated, and ACIP may update recommendations in the future 1.

Infant Passive Immunization (Nirsevimab)

Monoclonal antibody protection differs from vaccine-derived immunity:

• Studies of antibody levels suggest that protection from nirsevimab might wane more slowly than protection from maternal RSV vaccine 1
• Each injection of palivizumab (an older monoclonal antibody) helps protect for about 1 month, requiring monthly dosing during RSV season 6
• Results from clinical trials indicate that palivizumab trough serum concentrations 30 days after the fifth dose remain well above protective concentrations for most infants 1
• Five monthly doses of palivizumab provide substantially more than 20 weeks of protective serum antibody concentrations for most of the RSV season 1

Clinical Algorithm for Duration Considerations

For adults aged ≥60 years:

1. Administer one dose preferably between August-October 1
2. Do not revaccinate for at least two full RSV seasons 1, 2
3. Monitor for future ACIP guidance on revaccination intervals 1
4. Consider that immunocompromised patients may have reduced duration of protection 3

For pregnant persons:

1. Vaccinate once between 32-36 weeks gestation during September-January 1
2. Expect infant protection primarily during first 3 months of life 1
3. Plan for nirsevimab if infant will be <8 months during RSV season and maternal antibodies have waned 1
4. Await future guidance on revaccination in subsequent pregnancies 1

For infants receiving nirsevimab:

1. Single dose provides protection through one RSV season 1
2. Infants aged 8-19 months at increased risk entering their second RSV season require another dose 1

Common Pitfalls to Avoid

Do not assume indefinite protection: While current recommendations state a single lifetime dose for adults, ongoing monitoring is evaluating optimal revaccination intervals, particularly given the observed decline in effectiveness from same-season to prior-season vaccination 1, 3.

Do not provide both maternal vaccine and infant nirsevimab: Both products are not needed for most infants, as this represents unnecessary intervention 1, 4.

Do not delay adult vaccination beyond early fall: Vaccination should occur between August-October for maximum benefit during peak RSV season, even though protection extends beyond one season 1, 2.