How soon will I need a second vaccination with COVID-19?
The first COVID-19 vaccines in the US require two doses a few weeks apart.
Humans should receive some degree of protection within two weeks of the first injection, with the second injection achieving full protection of the vaccine. For the vaccine from Pfizer and Germany’s BioNTech, the second injection should be after three weeks. For Moderna it is four weeks.
But how closely those guidelines should be followed has been a point of difference for the United States and the United Kingdom, which has rolled out the Pfizer vaccine, and one by Astrazeneca that requires two doses four weeks apart.
In order to get more first shots at people and give them at least some measure of protection, the UK says it’s okay to delay the boosters for 12 weeks. But that strategy has been circumvented in the US, where regulators say there is no science to back up the approach.
A major concern is that it is not known how long partial protection against a single dose can last. “There is no data to show that protection lasts after the first dose after 21 days,” said Pfizer.
US regulators agreed, saying too few people in the Pfizer and Moderna vaccine studies missed their planned boosters to have enough data to show that the strategy could work.
However, the timing of the recordings does not have to be exact in the US; the Centers for Disease Control and Prevention say the second shots can be given up to four days earlier or later.
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The AP answers your questions about the corona virus in this series. Submit them to: [email protected].
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