Alternative Dosing

Close-up medical syringe with a vaccine.

Alternative dosing is finally getting some attention. This story in Nature recounts some of the recent arguments and evidence:

Two jabs that each contained only one-quarter of the standard dose of the Moderna COVID vaccine gave rise to long-lasting protective antibodies and virus-fighting T cells, according to tests in nearly three dozen people1. The results hint at the possibility of administering fractional doses to stretch limited vaccine supplies and accelerate the global immunization effort.

Since 2016, such a dose-reduction strategy has successfully vaccinated millions of people in Africa and South America against yellow fever2. But no similar approach has been tried in response to COVID-19, despite vaccine shortages in much of the global south.

“There’s a huge status quo bias, and it’s killing people,” says Alex Tabarrok, an economist at George Mason University in Fairfax, Virginia. “Had we done this starting in January, we could have vaccinated tens, perhaps hundreds, of millions more people.”

…Sarah Cobey, an infectious-disease researcher at the University of Chicago in Illinois and a co-author of a 5 July Nature Medicine commentary supporting dose ‘fractionation’, disagrees about the need for time-consuming data collection.

“We shouldn’t wait that long,” she says. “People are dying, and we have historical precedent for making very well-reasoned guesses that we think are going to save lives.”

…According to a modelling study published by Tabarrok and other economists, such an approach would reduce infections and COVID-linked deaths more than current policies.

Addendum: The reason for doing the modeling study is precisely to take into account variants like Delta. Our modeling suggests that even with efficacy significantly lower than that suggested by Figure 1 in our paper, alternative doses of more effective vaccines would still provide significant reductions in mortality, even when new variants dominate. The benefits derive from vaccinating more quickly.

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