Booster shots less effective in people with weakened immune systems: study
Vaccines against the coronavirus were significantly less effective in protecting people with weakened immune systems than others, the Centers for Disease Control and Prevention reported on Tuesday, reinforcing the agency’s call for immunocompromised adults to receive a third or fourth dose of vaccine.
Two doses of Pfizer-BioNTech or Moderna vaccines were 77% effective against COVID-related hospitalizations for immunocompromised people. It was a significant level of protection, the agency said, but far less than the benefits of injections for people without immunodeficiency: in these people, the agency said, the vaccines were 90% effective against related hospitalizations. to COVID.
The Moderna vaccine also offered more protection to people with weakened immune systems than the Pfizer vaccine, mirroring the results seen in American adults. And some immunodeficient people – particularly organ or stem cell transplant recipients, who often take drugs to suppress their immune system and prevent transplant rejection – have shown weaker responses to COVID vaccines than others. categories of immunocompromised people.
The study did not examine recipients of the Johnson & Johnson vaccine.
To help people who are immunocompromised develop a more aggressive immune response, the CDC suggests giving them three doses of Pfizer or Moderna vaccines, as well as an additional booster six months after the third dose. In addition, the agency’s scientists wrote, they should take precautions like wearing masks and be considered for treatments like monoclonal antibody therapy as soon as possible after a diagnosis of COVID.
The study published on Tuesday used a devious experimental design. Researchers examined about 20,000 immunocompromised adults and 70,000 people without immune deficiencies hospitalized this year with COVID-like illness. Of the immunocompromised patients in the study, 43 percent were fully immunized. Of the other participants, 53% were vaccinated.
The researchers then determined how many of those hospitalized patients were actually infected with the coronavirus, and compared the odds of a positive test result between fully vaccinated and unvaccinated patients.
Immunocompromised patients included those with cancer, inflammatory disorders, organ or stem cell transplants, and other immune deficiencies.
The study authors warned that there could have been cases in which patients were wrongly classified as immunocompromised, and that there could have been biases in which patients sought coronavirus tests.
This article originally appeared in The New York Times.