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# No Evidence Supporting Covid Vaccine Dosing Changes: FDA
- URL: https://www.fdaweb.com/no-evidence-supporting-covid-vaccine-dosing-changes-fda/
- Published: 2021-01-05T12:00:00.000Z
- Updated: 2026-09-14T16:41:26.000Z
- Author: David McFarland
- Tags: Biologics, #legacy-id-D5148384

FDA commissioner **Stephen Hahn** and CBER director **Peter Marks** say the available data “continue to support the use of two specified doses of each authorized \[Covid-19\] vaccine at specified intervals.” Hahn and Marks issued a joint [statement](https://www.fda.gov/news-events/press-announcements/fda-statement-following-authorized-dosing-schedules-covid-19-vaccines?ref=fdaweb.com) to counter mass media articles and opinion pieces, such as this [one](https://www.washingtonpost.com/opinions/2021/01/03/its-time-consider-delaying-second-dose-coronavirus-vaccine/?ref=fdaweb.com) from the *Washington Post*, suggesting changes to the vaccine administration to counteract the current slow rollout and make the available vaccine doses go further to cover more people.

“We want to remind the public about the importance of receiving Covid-19 vaccines according to how they’ve been authorized by FDA in order to safely receive the level of protection observed in the large randomized trials supporting their effectiveness,” Hahn and Marks write. “At this time, suggesting changes to the FDA-authorized dosing or schedules of these vaccines is premature and not rooted solidly in the available evidence. Without appropriate data supporting such changes in vaccine administration, we run a significant risk of placing public health at risk, undermining the historic vaccination efforts to protect the population from Covid-19.”

Hahn and Marks say the notion of using a single dose regimen and/or administering less than the dose studied in the clinical trials without understanding the nature of the depth and duration of protection that it provides is concerning, as there is some indication that the depth of the immune response is associated with the duration of the protection provided. “If people do not truly know how protective a vaccine is, there is the potential for harm because they may assume that they are fully protected when they are not and, accordingly, alter their behavior to take unnecessary risks,” they say. “Until vaccine manufacturers have data and science supporting a change, we continue to strongly recommend that healthcare providers follow the FDA-authorized dosing schedule for each Covid-19 vaccine.”