Authorized coronavirus disease 2019 (COVID-19) vaccines should be administered as indicated in the emergency use labeling, according to the Food and Drug Administration (FDA).

Following multiple discussions and news reports on how to increase the number of vaccinated individuals, the Agency issued a statement saying that at this time reducing the number of doses, changing the quantity of the dose, or extending the length of time between doses are not evidence-based options.

Currently, Emergency Use Authorization (EUA) has been granted to Pfizer-BioNTech’s BNT162b2 vaccine and Moderna’s mRNA-1273 vaccine, both indicated for active immunization to prevent COVID-19. The BNT162b2 vaccine is administered intramuscularly as a 2-dose series (0.3mL each) spaced 21 days apart, while the mRNA-1273 vaccine is administered intramuscularly as a series of 2 doses (0.5mL each), given 28 days apart.

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“What we have seen is that the data in the firms’ submissions regarding the first dose is commonly being misinterpreted,”  said FDA Commissioner Stephen M. Hahn, MD. “Those participants who did not receive 2 vaccine doses at either a 3-or 4-week interval were generally only followed for a short period of time, such that we cannot conclude anything definitive about the depth or duration of protection after a single dose of vaccine from the single dose percentages reported by the companies.”

Hahn noted that additional research from the vaccine manufacturers would be needed to support any changes to the dosing schedule. In the meantime, the Agency “strongly” recommends that health care providers follow the FDA-authorized EUA labeling for each COVID-19 vaccine.


FDA statement on following the authorized dosing schedules for COVID-19 vaccines. [press release]. Silver Springs, MD: U.S. Food and Drug Administration; January 4, 2021.

This article originally appeared on MPR