Trial shows Pfizer RSV vaccine provides sustained protection in older adults over two seasons

Pfizer has announced that its vaccine against respiratory syncytial virus (RSV) has shown sustained protection in older adults over the course of two full seasons of the disease. While the efficacy of the vaccine declined slightly compared to after one RSV season, the data suggests that it still provides durable protection for adults aged 60 and above, who are more susceptible to severe illness from RSV.

The launch of Pfizer’s vaccine, known as Abrysvo, last year, along with another RSV shot from GlaxoSmithKline (GSK), has been highly successful for both companies. These vaccines have accounted for hundreds of millions in revenue within just half a year on the market.

According to the initial data on over 37,000 participants in the Northern and Southern Hemispheres, a single dose of Pfizer’s vaccine was 77.8% effective against more severe lower respiratory tract illness with three or more symptoms through a second season, down from 88.9% efficacy following the end of one season. The shot was approximately 55.7% effective against a less severe form of the illness with two or more symptoms after the end of season two, compared to 66.7% efficacy after one RSV season.

Pfizer highlighted that the vaccine maintained consistent efficacy against both major subtypes of the virus, RSV A and RSV B, after the second RSV season. It was specifically 80% or more effective against each subtype in patients with the more severe form of lower respiratory tract illness. Additionally, no new adverse events were reported by patients after the two seasons.

These results precede a meeting of an advisory panel to the Centers for Disease Control and Prevention (CDC) to discuss whether seniors should receive RSV shots annually or every other year. A final recommendation is not expected until June, but this decision could have significant implications for Moderna, which plans to launch its own RSV vaccine this year.

Analysts predict a 50% to 70% likelihood that the advisory panel will recommend annual vaccination, which would allow Moderna to gain market share comparable to Pfizer and GSK. However, if the recommendation is biennial, based on GSK’s two-season data, it may reduce Moderna’s competitive positioning.

GSK’s RSV vaccine demonstrated a cumulative efficacy of 67.2% against lower respiratory tract illness over two seasons, compared to 82.6% after one season of the virus. The vaccine generated approximately £1.2 billion ($1.5 billion) in sales last year. Pfizer’s vaccine, which is also approved for expectant mothers to pass on protection to their children, generated around $890 million in revenue in 2023.

RSV is responsible for the deaths of 6,000 to 10,000 older adults and the hospitalization of 60,000 to 160,000 individuals every year, according to the CDC.

The potential recommendation for annual RSV vaccination and the success of Pfizer and GSK’s vaccines highlight the growing importance of protecting older adults from this serious respiratory virus. With Moderna set to enter the market soon, competition is expected to increase, potentially leading to improved options and outcomes for vulnerable populations.