Limited benefits, optimal timing of a second COVID-19 booster debated

Mayo Clinic vaccinologist Dr. Greg Poland says the latest data show the benefit of a second booster is real, but "fractional" and wanes fast, meaning that timing and individual health circumstances are important factors when considering a fourth shot.

File: COVID-19 vaccine St. Luke's.jpg
Infectious disease nurse practitioner Sherry Johnson, of Duluth, uses a syringe to draw Pfizer-BioNTech COVID-19 vaccine from a vial in December 2020 at St. Luke's hospital in Duluth.
Clint Austin / Duluth News Tribune
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ROCHESTER, Minn. — With the recent FDA and CDC authorization of a second COVID-19 booster for individuals over 50 and those with compromised immune systems who are four months from their last shot, the limits to boosting are an increasing part of the calculation.

The role of manufacturers prior to the decision in promoting a fourth shot elicited skepticism last week in remarks to the media from Food and Drug Administration vaccine advisory panel expert Dr. Paul Offit, while epidemiologist Dr. Michael Osterholm has remarked that "we're not gonna be able to boost our way out of this."

The fourth shot protocol arrives as just 66% of Minnesotans have received their third shot, a first booster recognized as capable of raising antibodies 20-fold higher than the primary series, and one that seemingly corrected what some scientists believe was too short of an interval.

The new authorization also comes along in an environment of uncertainty about the next phase of the pandemic, with case counts low but, in a familiar pattern, climbing.

"This is a permissive recommendation, done in the interest of trying to get ahead of the next surge or increase in cases," Mayo Clinic vaccinologist Dr. Greg Poland said during a media call last week. "Remember, after each surge we in the U.S. have sort of said psychologically to ourselves that now we're headed toward an endemic phase ... (however) we've watched this movie five times with the same bitter ending."


"I think the (FDA) was trying to get ahead of that, and allow permissive recommendation, because once this surge starts, you can't immunize 300 million people inside of a day or a week or a month."

In authorizing second boosters, health officials have noted the results of a recent New England Journal of Medicine study of second boosters among older adults in Israel.

That study found a "modest absolute benefit" in the authors' words, data suggesting the fourth shot could reduce risk of infection and severe illness, but with just 4-8 weeks protection against new infection, and the length of protection against severe illness unknown.

Poland was quick to echo that the known risk reduction in absolute numbers from a second booster was "fractional."

"If you got this second booster you decreased the risk of dying of COVID-19 by 78%," Poland said, "that's the relative risk."

In real world numbers, he added, the risk of dying for those with three shots was already low, meaning the so-called "absolute risk reduction" from a second booster "decreased your risk of dying from .1% to .03% ... For about four to 12 weeks, and then it wanes again."

"So this is the dilemma: When do I pull the trigger on doing that? My recommendation would be that people who fit into the age group to get a booster, talk with their health care provider to understand their situation."

"Are you 70 with a list of 10 different medical problems? My recommendation is to pull the trigger. Are you healthy but ... going to travel to foreign location (with) high cases? Pull the trigger, and get your second booster. Are you 55 and healthy, living in rural Montana and absolutely careful ... I'd say watch closely, but hold."


Lest anyone forget, Poland says, those who have one booster and are healthy are still well protected against the worst outcomes.

"The vaccines remain extremely effective against death. Very effective against severe disease and mechanical ventilation. They are moderately effective against moderate infection and mildly effective against mild and asymptomatic disease."

Poland believes that a recent episode of COVID-19 infection also counts as a booster, possibly for six weeks or greater.

"I think we're all going to get (a second booster) eventually," he said. "It's a matter of when. The ideal is, you would like to get your booster two weeks before the surge, or before you were exposed. And there's no way to predict when that is."

Paul John Scott is the health correspondent for NewsMD and the Forum News Service. He is a novelist and was an award winning magazine journalist for 15 years prior to joining the FNS in 2019.
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