Covid vaccines continue to protect against serious illness and death, especially for people ages 65 and older, although the benefits for younger adults are not as clear, according to a large new study of veterans.
Researchers from the VA St. Louis Healthcare System analyzed data from nearly 300,000 veterans and found that last season’s Covid vaccine reduced the risk of emergency room visits by 29%, hospitalizations by 39% and deaths by 64% for all ages.
When the researchers combined the three outcomes, overall effectiveness was 28%, making the Covid vaccine similar to the yearly flu shot, which ranges from 30% to 60% protective against severe illness or death.
In the new study, published Wednesday in the New England Journal of Medicine, researchers used records from the Department of Veterans Affairs consisting of about 164,000 people who got either the Moderna or the Pfizer mRNA Covid vaccine and a flu shot at the same time last fall, as well as about 130,000 who got only the seasonal flu shot.
The participants were followed for six months to see how effective the Covid vaccines were against preventing emergency room visits, hospitalizations and deaths.
All ages got some protection from vaccination, but the results were more pronounced in older people and those with underlying health conditions, such as heart or lung disease.
For younger adults, the Covid vaccines were about 27% protective against ER visits, hospitalization or death for people under 65.
For people 65 and older, overall effectiveness was close to 40%.
The researchers declined to comment on the findings.
Dr. Michael Mina, an immunologist and former professor of epidemiology at the Harvard T.H. Chan School of Public Health, said the study showed “pretty modest benefits” from the Covid vaccines, which did not surprise him.
There are limitations to the study. The researchers categorized participants only by ages 65-75, over 75 and younger than 65. Mina said it would have been helpful to see effectiveness among more specific age groups to better determine whether a young healthy 25-year-old needs to get a Covid booster, for example.
“Each person in certain risk categories, especially the younger individuals, should have a discussion with their doctor,” Mina said. “Do they have heart disease? Do they have chronic lung disease? Have they been a long-term smoker?”
‘Still measurable benefit’
Bill Hanage, a professor of epidemiology at the Harvard T.H. Chan School, said that because so many people already have immunity against Covid, it can be harder to pinpoint vaccine effectiveness now. Still, he was pleased to see some protection for all age groups.
“The core message of this is that even now, with all of this vaccine-induced immunity and convalescent immunity floating around, there is still a measurable benefit,” he said.
Michael Osterholm, an infectious disease expert and the director of the Center for Infectious Disease Research and Policy at the University of Minnesota, said the study was well designed, and he was encouraged by the findings.
“As an individual who is older, I would very willingly get my booster dose of this vaccine if I could reduce the chance of dying from Covid by 64%,” Osterholm said.
The effectiveness of the vaccine also waned considerably over the six-month period, consistent with previous research.
The shots prevented 18 ER visits, 7 hospitalizations and 2 deaths for every 10,000 vaccinated people. The small difference may reflect the decreased severity of a “contemporary” Covid infection, the researchers wrote.
However, a winter surge could still have a measurable impact on society, said Dr. Peter Chin-Hong, an infectious disease physician at The University of California, San Francisco.
“If you multiply by millions of people, even those individual-level differences that might be modest would be translating into large numbers of people that would otherwise potentially strain the health system,” Chin-Hong said.
Confusion over Covid vaccine guidance
The study’s findings line up with the updated guidance from the Centers for Disease Control and Prevention recommending Covid shots for people 65 and older and only after they consult doctors or pharmacists.
However, there has been considerable confusion around the new Covid guidance. People younger than 65 are not barred from getting Covid vaccinations — they still can, although the CDC said “the risk-benefit of vaccination in individuals under age 65 is most favorable for those who are at increased risk for severe” illness.
Officials from the Food and Drug Administration, including its commissioner, Dr. Marty Makary, have recently argued that more data is needed to determine the benefits of Covid vaccination in young healthy adults.
However, Hanage worries that the current messaging around vaccines could ultimately have a negative effect on the most vulnerable.
“The message which is coming out at the moment is not helping vaccination, even in the older age groups, which is already way, way too low,” he said.
Less than half of adults ages 65 and older typically receive updated Covid vaccines, according to the CDC.
“Nobody would disagree that it’s more important by far to ensure that people who are over 65 have access to vaccines,” Hanage said.
Chin-Hong said that when young healthy people ask him whether they should get boosted, his advice is simple — talk to your doctor.