How quickly do I need a second COVID-19 vaccine?

How quickly do I need a second COVID-19 vaccine?

The first COVID-19 vaccines in the United States require two doses a few weeks apart.

People should achieve some degree of protection within two weeks of receiving the first vaccine, with the second providing full protection from the vaccine. For the vaccine from Pfizer and German BioNTech, the second injection is supposed to take place after three weeks. For Moderna, it’s four weeks.

But how well those guidelines should be followed has been a point of difference for the US and UK, which have rolled out the Pfizer vaccine and an Astrazeneca vaccine that requires two doses given four weeks apart.

To get more first shots on people and give them at least some degree of protection, the UK says it’s okay to delay recalls for up to 12 weeks. But that strategy has been overturned in the United States, where regulators say no science supports the approach.

A major concern is that it is not known how long partial dose protection can last. “There is no data to demonstrate that protection after the first dose is maintained after 21 days,” Pfizer said.

U.S. regulators agreed, saying too few people participating in the Pfizer and Moderna vaccine studies missed their scheduled boosts to have enough data to show the strategy might work.

The timing of the shots does not have to be exact in the United States, however; the Centers for Disease Control and Prevention says second injections can be given up to four days earlier or later.

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The AP answers your questions about the coronavirus in this series. Submit them to: [email protected].

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