Respiratory syncytial virus vial.
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PfizerThe respiratory syncytial virus vaccine maintained protection in older adults over two full seasons of the disease in an ongoing late-stage clinical trial, the company announced Thursday.
The shot's effectiveness declined slightly compared to protective levels after an RSV season, but the new data suggest the vaccine generally offers long-lasting protection for adults aged 60 and older, who are more vulnerable to severe illness from RSV. The launch of the Pfizer vaccine, known as Abrysvo, and another RSV shot from GlaxoSmithKline Last year turned out to be a blessing for both companies, with hits amounting to hundreds of millions in just half a year on the market.
A single dose of the Pfizer vaccine was 77.8% effective against more severe lower respiratory tract illnesses with three or more symptoms during a second season, compared to 88.9% effective after the end of one season. Those symptoms include wheezing, difficulty breathing, rapid, shallow breathing, and mucus production.
The vaccine was about 55.7% effective against a less severe form of that condition with two or more symptoms after the end of the second season, based on initial data from more than 37,000 participants in the northern and southern hemispheres. The vaccine showed 66.7% efficacy against that condition after one RSV season.
Pfizer noted that the vaccine showed consistent efficacy against RSV A and RSV B, which are the two main subtypes of the virus, after the second RSV season. The injection was specifically 80% or more effective against each type in patients with the most severe form of lower respiratory tract disease.
Patients reported no new adverse events after the two seasons.
The results come ahead of a meeting of a Centers for Disease Control and Prevention advisory panel on Thursday, which will consider whether older people should get the RSV vaccine annually or every two years.
Analysts don't expect the committee to make a final recommendation until June, a decision that could have huge implications for modernwhich hopes to launch its own RSV vaccine this year.
Jefferies analyst Michael Yee said in a note last week that the company sees a 50% to 70% chance the panel will recommend annual vaccination, which would put Moderna in a position to achieve “at least an equivalent market share” to Pfizer and GSK. A biennial recommendation based on GSK's shooting data over two seasons would “reduce Moderna's competitive positioning,” he said.
In older adults, GSK injection showed a cumulative efficacy of 67.2% against lower respiratory tract diseases over two RSV seasons. That compares to 82.6% after one season of the virus.
GSK's vaccine recorded around £1.2 billion ($1.5 billion) in sales last year. Meanwhile, Pfizer's vaccine, which is also approved for pregnant women who can pass protection to their children, posted about $890 million in revenue in 2023.
According to the CDC, RSV kills between 6,000 and 10,000 older adults and hospitalizes between 60,000 and 160,000 of them each year.
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