Johnson & Johnson’s Covid-19 vaccine should not replace second dose of the Moderna or Pfizer vaccines except in “exceptional situations,” says the US Centers for Disease Control and Prevention.
“Any of the currently authorized Covid-19 vaccines can be used when indicated, ACIP does not see a product preference,” said Dr. Sarah Mbaeyi, CDC medical officer Tuesday during the CDC Clinician Outreach and Communication Activity call.
“However, the Covid-19 vaccines are not interchangeable, and the safety and efficacy of a mixed product series has not been evaluated,” she said. “We don’t want people to just start mixing and matching with whatever is easiest to get.”
The CDC currently recommends two dose series for both the Pfizer and Moderna vaccines. The second dose of the Pfizer vaccine should be administered three weeks after the first, while people should wait four weeks before receiving the second dose of the Moderna vaccine.
If there are delays, the second dose can be administered up to six weeks after the first, according to updated CDC guidance, Mbaeyi said.
However, the CDC did say that in the rare circumstance a person is unable to receive their second Pfizer or Moderna dose, they can receive the Johnson & Johnson vaccine. But it must have been at least 28 days since receiving their first dose.
Mbaeyi added that it would be extremely unlikely that someone would be in this circumstance and people should not substitute the Johnson & Johnson vaccine if there’s “temporary unavailability of Pfizer or Moderna.”
The CDC is also recommending against fully vaccinated people signing up to receive the Johnson & Johnson vaccine.
“If somebody has completed a series, so they’ve gotten their Pfizer or Moderna series, they are considered vaccinated,” Mbaeyi said. “They do not need any additional Janssen vaccine to kind of boost their protection, and we’re recommending against that.”
The CDC clinical considerations will be updated to include Johnson & Johnson viral vector vaccine.