Does the Respiratory Syncytial Virus (RSV) vaccine prevent hospitalizations due to Respiratory Syncytial Virus (RSV) infection?

From the Guidelines

The RSV vaccine is highly effective in preventing hospitalizations due to RSV infection, with a single dose providing protection through one RSV season for adults 60 and older. The most recent and highest quality study, published in 2025 in the journal Pulmonology 1, recommends the RSV vaccine for people aged ≥50 years with risk factors and all persons aged ≥60 years. This study endorses the use of RSV vaccines in preventing RSV-associated disease and its complications in adults.

The RSV vaccines, including Arexvy and Abrysvo for older adults, have demonstrated significant effectiveness in reducing RSV-related hospitalizations across different age groups. Clinical trials have shown that these vaccines can prevent approximately 80-90% of severe RSV disease requiring hospitalization. The vaccines work by stimulating the immune system to produce antibodies against the RSV F protein, which the virus needs to enter human cells. By blocking this mechanism, the vaccines prevent the virus from causing the severe lower respiratory infections that typically lead to hospitalization.

Key points to consider when administering the RSV vaccine include:

• The vaccine should preferably be given between September and November
• It can be co-administered with the influenza vaccine
• Ongoing studies on RSV vaccines may justify extending these recommendations in the future
• The protection is particularly important for high-risk groups, including elderly adults, and those with chronic heart or lung conditions, as these populations face the greatest risk of severe RSV disease requiring hospital care, as noted in a previous study published in 2024 in the Morbidity and Mortality Weekly Report 1.

From the FDA Drug Label

The incidence of RSV hospitalization is shown in Table 1. The results were shown to be statistically significant using Fisher's exact test Table 1: Incidence of RSV Hospitalization by Treatment Group Trial | Placebo | Synagis | Difference Between Groups | Relative Reduction Trial 1 | 53 (10.6%) | 48 (4.8%) | 5.8% | 55% Trial 2 | 63 (9.7%) | 34 (5.3%) | 4.4% | 45%

The palivizumab (IM) vaccine prevents hospitalizations due to Respiratory Syncytial Virus (RSV) infection, with a relative reduction of 55% in Trial 1 and 45% in Trial 2, as shown in Table 1 2.

• The incidence of RSV hospitalization was lower in the Synagis group compared to the placebo group in both trials.
• The results were statistically significant using Fisher's exact test.
• The reduction of RSV hospitalization was observed in different subgroups, including children with BPD and premature infants without BPD.

From the Research

RSV Vaccine Efficacy

• The RSV vaccine has been shown to prevent hospitalizations due to RSV infection, with studies indicating a significant reduction in hospitalization rates 3, 4.
• A study published in 2023 found that two newly approved vaccines, Nirsevimab and RSVPreF3 OA, are effective in preventing acute and severe RSV-LRTI requiring hospitalizations 3.
• Another study from 2002 demonstrated a 55% reduction in hospitalization rate due to RSV infection in preterm infants treated with palivizumab, a monoclonal antibody against RSV 4.

Mechanism of Action

• The RSV vaccine works by inducing immunity against the two major strains of RSV, with a single dose required to provide protection 3.
• Palivizumab, a monoclonal antibody against the RSV F protein, has been shown to be effective in preventing severe RSV infection in high-risk infants 5, 6, 4.

Target Population

• The RSV vaccine is approved for infants born at 35 weeks of gestation and above, as well as adults aged 60 and older 3.
• High-risk infants, including those born preterm with or without bronchopulmonary dysplasia and those with hemodynamically significant congenital heart disease, are also eligible for palivizumab prophylaxis 6.

Efficacy and Optimization

• Studies have shown that optimized injection regimens of palivizumab can improve protection for children at risk for severe outcomes of RSV infection and lower rates of hospitalization due to RSV 7.
• A mathematical modeling study found that a 5-injection regimen of palivizumab can reduce hospitalization risk by a median of 2.7% compared to a conventional regimen 7.