In-Depth: With signs of waning immunity, will all adults need a second booster?

Vaccination COVID-19
Posted at 6:06 PM, Feb 17, 2022
and last updated 2022-02-17 21:06:00-05

SAN DIEGO (KGTV) – Dr. Anthony Fauci said the first four months of data on the effectiveness of booster shots show that protection remains strong, and a second booster is not yet needed.

A study released this month by the Centers for Disease Control and Prevention found protection from hospitalization during the omicron wave dropped from 91 percent in the first two months after the booster to 78 percent after four months.

“The level of 78 is still a good protective area,” Dr. Fauci said Wednesday, adding that the U.S. is “carefully monitoring” hospitalizations to see if waning drops further or levels off.

The study had an important caveat. The CDC did not analyze variations by age or underlying medical conditions, suggesting the effectiveness of one booster could be much higher in healthy people.

Currently, people who are “moderately or severely immunocompromised,” like cancer patients, are urged to get the equivalent of a second booster. That is a fourth dose for recipients of an initial mRNA series or a third dose for people who got Johnson & Johnson.

Countries like Israel, Chile, Denmark, and South Korea have expanded access to fourth doses to broader segments of their populations, but two experts contacted by ABC 10News agreed with Dr. Fauci’s assessment.

“It’s not needed yet at the population level,” said Dr. Ali Mokdad of the Institute of Health Metrics and Evaluation at the University of Washington.

Dr. George Rutherford, an epidemiologist at UC San Francisco, said health officials are trying to determine whether to recommend a fourth dose of the existing vaccine recipe or wait for a variant-specific booster ahead of the next cold and flu season.

“It’s waning a little bit, for sure. But the question is, can you do anything about it?” said Rutherford.

A study in Israel found that people 60 and older who got a fourth dose of Pfizer’s vaccine four months after their previous shot saw about four times as much protection from severe illness. However, there is very little data so far on whether a fourth booster helps younger people.

“What I want to do is see definitive studies that say, yes, this confers a definite benefit that lasts this long,” he said.

In the U.S., all adults became eligible for boosters three months ago, on November 19. With omicron infections steadily dropping, Dr. Mokdad said most Americans are well protected for now.

“But yes, it’s possible before summer, with waning immunity and if omicron is still spreading, some of us may need to go and get a fourth dose,” he said.

Earlier this month, Dr. Fauci said that if the U.S. expands recommendations for a fourth shot, it could be targeted based on age or underlying conditions to those who need it most.