What’s the Right Dose for Boosters?

The Biden administration says booster shots are coming, but the FDA hasn’t decided on the dose. Moderna wants a half-shot booster. Pfizer a full shot. But could the best dose for Americans and for the world be even less?

COVID-19 vaccines are the first successful use of mRNA vaccine technology, so a lot remains unknown. But identifying the smallest dose needed to provide effective boosting is critical to protect Americans from adverse effects, increase confidence in vaccines, and mitigate global vaccine inequity.

We’ve known since earlier this year that a half-dose of the Moderna vaccine produces antibody levels similar to the standard-dose and newer information suggests that even a quarter-dose vaccine may do the same. If a half or quarter dose is nearly as effective as a standard dose for first and second shots then a full dose booster may well be an overdose. The essential task of a booster is to “jog” the immune system’s memory of what it’s supposed to fight. Data from the world of hepatitis B suggest that the “reminder” need not be as intense as the initial “lesson.” And in the cases of tuberculosis, meningitis, and yellow fever vaccines, lower doses have been as good or better than the originals.

Lower doses could also reduce risks of adverse effects.

That’s myself and physicians Garth Strohbehn and William F. Parker on the Med Page Today. Strohbehn is an oncologist and specialist in optimizing doses for cancer drugs. William Parker is a pulmonologist and professor of medicine at the University of Chicago.

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