Researchers recommend postponing second dose of Pfizer vaccine as highly effective first

(Reuters) – Pfizer Inc.’s second dose of COVID-19 vaccine may be delayed to cover all priority groups because the first is highly protective, two Canadian researchers said in a letter published in the New England Journal of Medicine .

The vaccine was 92.6% effective after the first dose, Danuta Skowronski and Gaston De Serres said, based on a review of documents submitted by the drug’s manufacturer to the US Food and Drug Administration (FDA).

These results were similar to the efficacy of the first dose of 92.1% reported for Moderna Inc.’s mRNA-1273 vaccine, according to the letter released Wednesday.

In its response, Pfizer said alternative vaccine dosing schedules have yet to be evaluated and the decision rests with health officials.

Some countries, struggling with low supplies, are investigating dosing schedules or volumes that differ from how vaccines have been tested in clinical trials.

There are differences in the appropriateness of these strategies, with some arguing that the emergency of the pandemic requires flexibility, while others oppose moving away from data-driven approaches for the sake of opportunity.

Skowronski and De Serres cautioned that there might be uncertainty about the duration of protection with a single dose, but said giving the second dose one month after the first provided “little additional benefit to the patient. short term”.

Skowronski works at the British Columbia Center for Disease Control, while De Serres is from the Institut National de Santé Publique du Québec

In Britain, authorities said the data supported his decision to switch to a 12-week dosing schedule for Pfizer’s COVID vaccine. Pfizer and its partner BioNTech both warned that they had no evidence to prove it.

Pfizer’s vaccine can be taken 21 days apart.

The US FDA and the European Medicines Agency adhered to the tested interval in the trials.