How quickly do I need the second dose of the COVID-19 vaccine?
The first coronavirus vaccines to be administered in the United States require two doses a few weeks apart.
Those inoculated should have a certain degree of protection within two weeks after the first injection, while the second should provide full protection from the vaccine. In the case of the one developed by Pfizer and the German BioNTech, the second dose should be given after three weeks, while with Moderna, you have to wait four.
But the degree of compliance with these recommendations differs between the United States and Great Britain, where the one from Pfizer-BioNTech and one from AstraZeneca and the University of Oxford has begun to be administered, which requires two doses four weeks apart.
To allow more people to get the first dose of the drug, which would mean they have some level of protection, Britain says the booster dose can be delayed for up to 12 weeks. But that strategy has been rejected in the United States, where regulators say there are no scientific studies to back that approach.
One of the main concerns is the lack of knowledge about how long a single dose partial immunization may last. “There is no data to show that protection after the first dose is maintained after 21 days,” said Pfizer.
US regulators agree, claiming that too few of the participants in the Pfizer-BioNTech and Moderna drug studies missed the inoculation schedule to have data to show that such a strategy would work.
But the date on which the two doses are injected does not have to be exact in the United States: the Centers for Disease Control and Prevention in the country said that the second dose can be given up to four days before or after the designated day.
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