A single dose of the RSVPreF3 OA vaccine was effective against respiratory syncytial virus (RSV)-related acute respiratory infection (ARI) and lower respiratory tract (LRT) disease and severe RSV-related LRT disease among adults aged 60 years of age and older in 1 RSV season, according to study findings published in the New England Journal of Medicine.
The ongoing, randomized, placebo-controlled, phase 3 Adult Respiratory Syncytial Virus (AReSVi-006) phase 3 trial (ClinicalTrials.gov Identifier: NCT04886596) assessed the efficacy of GSK’s RSVPreF3 OA vaccine in 17 countries. Researchers reported results for the first RSV season in the Northern Hemisphere.
Adults at least 60 years of age were enrolled from May 25, 2021, to January 31, 2022, and were randomly assigned 1:1 to receive the RSVPreF3 OA vaccine or placebo. The primary objective was to evaluate the efficacy of 1 dose of the RSVPreF3 OA vaccine for prevention of RSV-related lower respiratory tract disease in 1 RSV season; this objective was considered met if the lower limit of the 2-sided confidence interval for the efficacy estimate was more than 20%. The primary endpoint was incidence of RSV-related lower respiratory tract disease, confirmed with reverse-transcriptase polymerase chain reaction.
The exposed population included 12,467 participants (mean [SD] age, 69.5 [6.5] years; 52% female) who received 1 dose of RSVPreF3 OA vaccine and 12,499 participants (mean age, 69.6 [6.4] years; 51.4% female) who received 1 dose of placebo.
Our results indicate that the RSVPreF3 OA vaccine provided protection across the clinical spectrum of RSV disease, from mild upper respiratory tract infection to severe lower respiratory tract disease.
In the modified exposed population, 47 participants (7 of 12,466 in the vaccine group and 40 of 12,494 in the placebo group) had an episode of RSV-related lower respiratory tract disease after a median follow-up of 6.7 months (maximum follow-up, 10.1 months). The vaccine efficacy was 82.6% (96.95% CI, 57.9-94.1) and met the primary objective. Comparable findings were observed in the exposed population.
The vaccine’s efficacy against severe RSV-related lower respiratory tract disease, diagnosed based on clinical signs or by the investigator, was 94.1% (95% CI, 62.4-99.9), with 1 case in the vaccine group and 17 in the placebo group. At least 1 episode of RSV-related acute respiratory infection occurred in 122 participants (27 in the vaccine group and 95 in the placebo group), for a vaccine efficacy of 71.7% (95% CI, 56.2-82.3).
Vaccine efficacy was observed against RSV-related lower respiratory tract disease for RSV A and B (84.6% and 80.9%, respectively) and against RSV-related acute respiratory infection (71.9% and 70.6%, respectively). In participants aged 60 to 69 years and 70 to 79 years, vaccine efficacy against RSV-related lower respiratory tract disease was more than 80%.
In the solicited safety population (n=1757), pain was the most frequently occurring injection-site reaction (60.9% in the vaccine group and 9.3% in the placebo group), and fatigue was the most common solicited systemic reaction (33.6% and 16.1%, respectively). Most solicited reactions were mild or moderate.
Among the exposed population, 22,666 participants (90.8%) completed 6 months of follow-up, in which 4.2% of the vaccine recipients and 4.0% of the placebo recipients had a serious adverse event. Death occurred in 49 participants who received a vaccine (0.4%) and 58 who received placebo (0.5%).
Limitations include the small proportion of frail participants and of participants who were 80 years of age and older, as well as the study’s limited ability to detect rare side effects. In addition, public health measures to limit COVID-19 reduced the spread of RSV and affected the timing of the RSV season, with most cases of RSV-related acute respiratory infection occurring earlier in the season than anticipated. In response, the investigators increased the sample size and began the trial several months before the historical onset of the RSV season in the Northern Hemisphere.
“Our results indicate that the RSVPreF3 OA vaccine provided protection across the clinical spectrum of RSV disease, from mild upper respiratory tract infection to severe lower respiratory tract disease,” the researchers commented.
Disclosure: This research was supported by GlaxoSmithKline Biologicals. Some of the study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.