1. A single dose of the respiratory syncytial virus (RSV) prefusion F protein vaccine had an acceptable safety profile in adults 60 years of age or older.

2. A single dose of the RSV prefusion F protein vaccine prevented RSV-related acute respiratory infections in adults 60 years of age or older as compared to a placebo. 

Evidence Rating Level: 1 (Excellent)

Study Rundown: RSV is a significant cause of acute respiratory infections as well as lower respiratory tract disease in older adults or those with coexisting comorbidities. Treatment of RSV-associated illness is typically supportive, with no recommended vaccines or prophylaxis for older adults. Given the surge of RSV in the past year, it is critical that intervention and prevention strategies be investigated for vulnerable populations. However, a recent candidate RSV vaccine (RSVPreF3 OA) has been proposed to be effective in inducing an RSV-neutralizing antibody response in older adults. However, there is still a gap in knowledge as to understanding the efficacy of the RSVPreF3 OA vaccine in preventing RSV-related lower respiratory tract disease in adults 60 years of age or older. Overall, this study found that a single dose of the RSVPreF3 OA vaccine was efficacious in preventing RSV-related lower respiratory tract disease, RSV acute respiratory infection, and severe RSV lower respiratory tract disease in adults 60 years of age or older during one RSV season, regardless of RSV sub-type and baseline coexisting conditions and frailty status.

Click to read the study in NEJM

Relevant Reading: Prefusion F Protein–Based Respiratory Syncytial Virus Immunization in Pregnancy

In-Depth [randomized controlled trial]: This randomized, placebo-controlled phase three trial was conducted in 17 countries. Patients who were 60 years of age or older and had not been enrolled in another RSV vaccine trial were eligible for the study. Conversely, patients who were not medically stable were ineligible for the study. Participants were followed for three consecutive RSV seasons in the Northern Hemisphere and at least two consecutive seasons in the Southern Hemisphere. The primary endpoint was RSV-related lower respiratory tract disease as confirmed by reverse transcriptase polymerase chain reaction (RT-PCR). Outcomes in the primary analysis were assessed via a primary efficacy analysis with a conditional exact binomial method based on the Poisson model. Based on the primary analysis, with a median follow-up of 6.7 months, vaccine efficacy against RT-PCR–confirmed RSV-related lower respiratory tract disease was 82.6% (96.95% Confidence Interval [CI], 57.9 to 94.1), with seven cases (1.0 per 1000 participant-years) in the vaccine group and 40 cases (5.8 per 1000 participant-years) in the placebo group. Vaccine efficacy was 94.1% (95% CI, 62.4 to 99.9) against severe RSV-related lower respiratory tract disease (assessed on the basis of clinical signs or by the investigator) and 71.7% (95% CI, 56.2 to 82.3) against RSV-related acute respiratory infection. The RSVPreF3 OA vaccine was more reactogenic than the placebo, but most adverse events reported were mild to moderate in severity. In summary, this study demonstrated that a single dose of the RSVPreF3 OA vaccine had an acceptable safety profile and prevented RSV-related acute respiratory infection, lower respiratory tract disease, and severe RSV-related lower respiratory tract disease in adults 60 years of age or older.

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