Americans ages 65 and older should receive an additional dose of the latest Covid vaccine this spring, the Centers for Disease Control and Prevention said on Wednesday.
The spring shot would be a second dose of the most recent iteration of the Pfizer-BioNTech, Moderna or Novavax vaccines introduced in the fall. People who are immunocompromised are already eligible for additional doses of the vaccine.
At a meeting of the agency’s Advisory Committee on Immunization Practices earlier on Wednesday, federal researchers presented preliminary data showing that the latest vaccines have an effectiveness of about 40 to 50 percent against symptomatic infection or hospitalization, although estimates against currently circulating variants were based on small numbers.
In October and November, adults who received a fall dose accounted for 4 percent of Covid-related hospitalizations. Those who got a booster in the fall of 2022, but not the updated vaccine this fall, accounted for 25 percent.
Still, a second dose this spring would not be cost-effective for adults 18 to 64 years old, who are at lower risk of severe illness and hospitalization than older adults, according to modeling presented at the meeting.
Older adults and those with weakened immune systems because of illnesses or medications would benefit the most from a spring dose, the advisers concluded.
“I was impressed with data supporting the need for an additional dose of vaccine for those 65 years and older,” Dr. Camille Kotton, a physician at Massachusetts General Hospital and a member of the scientific advisory panel, said in an interview.
“Given the risk of severe, even life-threatening, disease, I would encourage those who are moderately to severely immunocompromised to take the opportunity for another dose,” she added.
Adults ages 65 and older accounted for two-thirds of all hospitalizations related to Covid between October 2023 and January 2024, and those ages 75 and older accounted for nearly half. Adults in this age group were also the most likely to have opted for the fall shot.
More than 43 percent of Americans aged 75 and older got the fall shot, compared with fewer than 10 percent of adults aged 18 to 29 years. Vaccination rates were lowest among Native Americans and Alaska Natives, and among those who lived in rural areas. Fewer than 13 percent of pregnant women opted for the vaccine.
Nearly half of those who did not plan to get the vaccine said they were concerned about unknown serious side effects, according to data from the National Immunization Survey in January.
Other reasons for the low uptake may be the lack of vaccine availability in the first few weeks following the C.D.C.’s recommendation, and confusion over insurance coverage for the shots.
The agency’s advisers met in September to discuss whether to recommend the shots, and for whom, but that allowed little time for vaccine manufacturing and distribution before the fall peak of infections, said Lakshmi Panagiotakopoulos, an infectious disease physician and C.D.C. researcher.
Dr. Panagiotakopoulos presented a revised plan for a decision on next fall’s Covid shot, with the C.D.C. advisers meeting in June to make recommendations regarding who should get the vaccine. A meeting of advisers to the Food and Drug Administration, which must precede the C.D.C. guidance, is already scheduled for May 16.
At the meeting on Wednesday, C.D.C. advisers wrestled with whether to suggest that older adults “may” opt to get a spring Covid vaccine in consultation with their health care providers, or to recommend more emphatically that they “should” do so.
Some panelists said the softer recommendation would be more palatable to Americans, and less likely to contribute to vaccine fatigue. Others argued that stronger language would make it clearer to those at high risk from the virus that a vaccine would afford them protection through the spring.
The advisers ultimately voted to recommend that Americans ages 65 and older “should” receive a spring shot. Dr. Cohen, the C.D.C. director, accepted the recommendation later in the day.
“I hope that clarity of the need for a second dose may encourage vaccination and protection in both those who have not yet had a first vaccine and those who would benefit by a second vaccine,” Dr. Kotton said.