The CDC updated federal vaccine recommendations Jan. 21 to allow second COVID-19 doses from a different manufacturer in "exceptional situations," reports The New York Times.
The agency also said people may receive a second dose up to six weeks after the first if it's not feasible to follow the recommended four-week window.
The CDC's "intention is not to suggest people do anything different, but provide clinicians with flexibility for exceptional circumstances," spokesperson Kristen Nordlund told the Times.
The new guidelines still assert that approved COVID-19 vaccines are not interchangeable. However, they do allow for any available mRNA vaccine to be used for the second dose if the "first-dose vaccine product cannot be determined or is no longer available," the guidelines state.
While Pfizer and Moderna's vaccines both rely on the same mRNA technology, the CDC's Advisory Committee on Immunization Practices recommended against mixing vaccine doses. The guideline change marks the first time the CDC has strayed from the advisory group's COVID-19 vaccine recommendations.
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