ATLANTA — Timing is critical when it comes to the COVID-19 vaccine, and medical experts are saying it’s better to get your second dose later than sooner.
Both the Pfizer and Moderna vaccines require two doses. Work continues on Johnson & Johnson’s single-dose vaccine that could be available in the coming weeks.
If you get the Pfizer vaccine, it’s recommended that you get your second dose three weeks after the first. If you go for the Moderna vaccine, the wait between doses is 28 days.
That’s what worked when the vaccines were tested in clinical trials.
“We’d like people to try to get it right around that either 21 or 28 day mark,” said Dr. John Brooks of the CDC. “I wouldn’t get hung up on getting it exactly on that, but try to get it within a couple of days of that date.”
The first shot primes your immune system. As it’s ramping up, your immune system is learning about the coronavirus and building a memory it will rely on if it ever encounters the virus.
The second shot expands and reinforces that memory.
If you get the second shot too soon, it’s like interrupting a study session for your big history exam.
“You need to have time for that memory to establish,” said Dr. Mark Tompkins of the University of Georgia Center for Vaccines and Immunology. “So if you rush too much, it’s just you don’t take advantage of that memory.”
Dr. Tompkins said it’s better to get your second dose a little later than too soon.
“We could certainly take it out further without any ill effects, but I don’t know how much further that is,” said Tompkins.
Which is why public health experts advise getting the second dose as close to the recommended date as possible.