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Public health expert talks about effectiveness of a second COVID-19 vaccine booster

A woman receives a COVID-19 vaccine at the vaccination super station at Grossmont Center in La Mesa, Calif. Feb. 2, 2021.
Roland Lizarondo
A woman receives a COVID-19 vaccine at the vaccination super station at Grossmont Center in La Mesa, Calif. Feb. 2, 2021.

A new study published in the New England Journal of Medicine Wednesday evaluated the early effectiveness of a second COVID-19 vaccine booster for people over the age of 60. The data from the study came from Clalit Health Services, the largest health care organization in Israel.

The results of the study supported the Centers for Disease Control and Prevention recommendation that people over the age of 50, who got their first COVID-19 vaccine booster more than four months ago, should get a second booster shot to strengthen protection against the virus.

RELATED: UCSD joins clinical trial to evaluate need for additional COVID-19 boosters


The results from the analysis show a 52% reduction in COVID-19 infections, a 72% reduction in hospitalizations and a 76% reduction in COVID-related deaths in participants over 60 who had a second booster.

Dr. Christian Ramers, assistant medical director at Family Health Centers of San Diego, who also sits on San Diego County’s vaccine clinical advisory group, joined KPBS Midday Edition to talk about the results of the study, and the effectiveness of a second COVID-19 vaccine booster for eligible people.

"This is now the second of two really large studies that are done in Israel, which has been really on the forefront of pushing the limits of additional boosters and additional vaccines," Ramers said. "This one in particular, there were 182,000 people, and they really looked at the comparison of those that had just a single booster, or three shots all together, or a second booster, four shots, with that second booster coming four months after the first one. And really across the board, there were really good benefits with not much added risk at all."

Ramers said people who received one or two of the initial vaccine doses but no booster could have waning immunity against the virus.

"We think (immunity) goes away pretty quickly in terms of the antibody levels. And with a new variant that comes along like omicron, those people that only got two doses were quite vulnerable to getting infected, and then did suffer more severe disease than those who had gotten their booster," Ramers said.


He said the frequency of COVID-19 vaccines and boosters needed in the future to maintain immunity to COVID-19 variants remains unclear.

"The FDA met to discuss the future on April 6, and there's a lot of uncertainty, so we're in a difficult spot right now about strategizing what to do in the fall," Ramers said. "Part of that is because we're still using the same original vaccine from the Wuhan strain, and the idea that we should be able to adapt a little better is something on everyone's minds. One of the comments in that meeting was we can't just keep boosting ourselves forever, but it does make sense that an annual boost may be tailored to the variant that's circulating at that time — similar to what we do with the influenza vaccine may be where we're headed."

He said the pharmaceutical companies Moderna and Pfizer and its German partner BioNTech are currently testing omicron-specific variant vaccines, and also vaccines that would protect against multiple variants in one.

As of Thursday, according to statewide vaccination data per county, 47.3% of eligible San Diego County residents have received a COVID-19 booster.