Respiratory syncytial virus: viral vaccine under investigation
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a vaccine Pfizer showed the potential to protect adults ages 18 to 59 who are at higher risk of severe illness from respiratory syncytial virus in a late-stage clinical trial, the company said Tuesday.
Initial data suggests that Pfizer's shot, known as Abrysvo, could help protect a much broader population from RSV. The vaccine is currently approved in the U.S., Europe, Japan and other countries for adults age 60 and older and pregnant women who can pass protection to their fetuses.
But there are no RSV vaccines approved worldwide for younger, high-risk adults.
RSV causes thousands of hospitalizations and deaths among older Americans and hundreds among infants each year. The virus can also cause serious illness in younger adults with weakened immune systems or underlying chronic diseases such as asthma and diabetes.
According to Pfizer, nearly 10% of American adults ages 18 to 49 have a chronic illness that puts them at risk for severe RSV disease. That number increases to about 24% for those between 50 and 64 years old.
“I think about my own family and friends who have asthma or suffered from illnesses since childhood,” Dr. Iona Munjal, Pfizer's executive director of clinical vaccine research and development, told CNBC. “That population is at risk of getting RSV every winter… over and over again. There is no lasting immunity without vaccination.”
Munjal added that high-risk adults ages 18 to 59 are the “next logical step” after working to reduce rates of RSV disease in older populations.
The data comes as Pfizer tries to gain more share in the RSV market after falling behind. GlaxoSmithKline last year. GSK's RSV vaccine for adults aged 60 and over recorded around £1.2 billion ($1.5 billion) in sales last year. Meanwhile, Pfizer's vaccine recorded revenue of about $890 million in 2023.
Pfizer said it plans to submit the data to regulatory agencies and apply for expanded approval of Abrysvo for those 18 and older. The company did not provide any details on the timeline for those plans.
Pfizer also intends to present the final results of the trial at an upcoming scientific conference and submit them for publication in a peer-reviewed journal.
Initial safety and efficacy data.
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Pfizer said Tuesday that its vaccine met key phase three trial goals for efficacy and safety in high-risk adults ages 50 to 59.
The company specifically released data on a substudy that examined nearly 700 patients who are at high risk for severe RSV due to underlying medical conditions. Pfizer expects to publish data on another substudy in about 200 patients with weakened immune systems later this year, Munjal told CNBC.
According to the results, a single dose of the drugmaker's injection triggered an immune response against RSV A and RSV B, which are the two main subtypes of the virus.
The immune response was similar to that observed in adults 60 years of age or older. Previous late-stage research in more than 30,000 adults in that older age group found that the Pfizer shot maintained protection against RSV for two full seasons of the virus.
“The level of antibodies seen after vaccination in those aged 18 to 60 is similar to those aged 60 and older,” Munjal told CNBC. He later added that “it gives confidence that in those two populations, they are actually responding to the vaccine in the same way and therefore are likely to have similar efficacy.”
Participants also saw a four-fold increase in their levels of protective antibodies against RSV A and RSV B one month after receiving the Pfizer shot compared to before vaccination.
The company said the vaccine was well tolerated by patients in the trial. Safety data in high-risk adults ages 18 to 59 were consistent with results in adults ages 60 and older, Pfizer added.
GSK released late-stage trial data in October suggesting its vaccine could protect adults aged 50 to 59.
In February, the Food and Drug Administration granted “priority review” to GSK's application to expand approval of its drug, Arexvy, to that new age group. That designation speeds up the review process for certain drugs for serious conditions.
The FDA is expected to decide whether to approve GSK's RSV vaccine for adults ages 50 to 59 on June 7.
