Pfizer adult RSV vaccine efficacy declines barely after 18 months

Pfizer‘s vaccine that protects adults ages 60 and older from respiratory syncytial virus was barely less effective after 18 months, in response to clinical trial results the corporate announced Wednesday. 

The information is from Recent York-based Pfizer’s clinical trial on greater than 34,000 older adults over two RSV seasons. The newest data is specifically on participants within the Northern Hemisphere at “mid-season two” in the trial, which is around 18 months after vaccination. 

The shot was 78.6% effective against more severe lower respiratory tract illness with three or more symptoms through mid-season two, down marginally from 85.7% through the top of season one. Those symptoms include wheezing, shortness of breath, rapid and shallow respiration, and mucus production.

The vaccine was roughly 49% effective against the identical condition with two or more symptoms through mid-season two, in response to Pfizer. That is a steeper decline from the shot’s 66.7% efficacy through one season. 

The vaccine was generally well tolerated, with no hostile events reported by participants through mid-season two.

Pfizer presented the outcomes to an advisory committee of the Centers for Disease Control and Prevention on Wednesday. The committee will form a suggestion on how often the corporate’s RSV vaccine needs to be administered within the U.S., equivalent to whether the shot needs to be on an annual schedule.

The advisors can even recommend the shot to a selected age group.

Pfizer’s RSV vaccine is the second to win Food and Drug Administration approval after a shot from GlaxoSmithKline, which is able to present similar longer-term data on Wednesday. 

Pfizer’s results are a primary glimpse at its vaccine’s durability in protecting against RSV, which causes mild symptoms just like a chilly in most individuals but more severe infections in older adults and kids.

The information suggests that the protection the vaccine provides slowly wanes over time, just like what’s observed with shots for Covid and the flu.

However the mid-season two data also suggests Pfizer’s shot remains to be generally protective against RSV after one yr.

It’s still unclear what the vaccine’s efficacy will appear like over two full seasons. Pfizer expects to release that data later this yr, which is able to provide a greater picture of the shot’s durability.

Annaliesa Anderson, head of Pfizer’s vaccine research and development, told CNBC that the corporate is “very encouraged” by data from the phase three clinical trial. 

She noted the vaccine maintained high efficacy against lower respiratory tract illness with three or more symptoms, which is more severe than the identical condition with two or more symptoms. 

“As with most vaccines, you are really searching for an impact against more severe disease that causes higher levels of mortality, morbidity and health-care associated contact,” Anderson told CNBC. “To find a way to see high efficacy carrying on could be very necessary to us, and we expect it should provide people comfort as they take the vaccine.”

Pfizer hasn’t released data on the effectiveness of its vaccine against severe RSV disease defined as a patient requiring hospitalization, oxygen support or a mechanical ventilator. 

Anderson said studies are ongoing, and so is research evaluating the shot’s efficacy in older adults with weak immune systems. 

RSV kills 6,000 to 10,000 older adults and hospitalizes 60,000 to 160,000 of them every yr, in response to the CDC. 

The danger of hospitalization increases with age, and adults ages 70 and older are more vulnerable.

Pfizer estimates that if 50% of individuals ages 60 and older receive its shot for older adults, the vaccine could prevent greater than 5,000 deaths, 68,000 hospitalizations, 51,000 emergency department visits and greater than 422,000 outpatient visits.