Is there a time limit to get your second Pfizer or Moderna shot?

The vaccine companies have given guidance about leeway time if you’re past the 21 or 28 day limit for second doses

Is there a time limit to get your second Pfizer or Moderna shot?
Is there a time limit to get your second Pfizer or Moderna shot?

SAN ANTONIO – Is there a time limit to get your second COVID-19 vaccine?

If you got your first vaccine from Pfizer or Moderna, it’s important to note that you still need to receive a second dose to be considered fully vaccinated. But what happens if you miss your vaccine appointment or forget?

Pfizer recommends that you get the second dose 21 days after your first dose. Moderna recommends that patients getting the second shot 28 days after getting the first dose.

“The interval between the prime shot and the boost was chosen based on previously known responses to vaccines in both animal models and human studies,” said UT Health San Antonio infectious disease expert Dr. Ruth Berggren.

Berggren said while the coronavirus pandemic was raging worldwide, there wasn’t enough time for researchers to design complex studies for 5 or 6-week intervals.

“We know we got really great results, 94 or 95% protection,” Berggren said. “So, if you want to have the outcome that is promised, you should get the vaccine in the way it was studied.”

Getting that second dose on time is the goal and the best way to ensure you get the full protection the studies promise. However, there are recommendations about leeway for the second dose.

“There is definitely a two-day grace period for getting your shot two days early,” Berggren said. “That can happen.”

As for the cutoff for getting the second shot late, Berggren said the Centers for Disease Control and Prevention lists 42 days as the outer limit. Meaning three weeks late for the Pfizer second dose or two weeks late for the Moderna second dose.

That limit has to do with the amount of protection the doses can offer patients.

Berggren said if you’re past that 42-day limit, you still can get the shot and many health professionals recommend it.

“It’s better to do that than to remain only partially protected,” Berggren said. “But understand it was never studied this way, so no one can tell you you’re protected.”

If you’ve missed out on getting your second shot, Berggren said it’s not too late to change that.

“The shot itself given late is not going to, in itself, harm you at all,” Berggren said. “The problem is when the shot is given much later than the recommended and studied interval, it may not be as protective as it is for everybody else.”

According to Berggren, no one should be turned away from a vaccine site because they are past the 42-day limit, but if that happens, she suggests trying another site or even getting a doctor’s note.

“Do a quick telehealth visit. Get a consultation and I can’t imagine a vaccinator would turn you away with a doctor’s note saying, ‘This is my patient who is coming late for a vaccine because of a medical issue. Please provide them with the vaccine as soon as possible,’” Berggren said.

Michelle Vigil, a Metro Health representative, agreed with Berggren and said it is recommended that people go to the same location to get their second shot as they did the first. However, it’s not mandatory.

Berggren said that the most important thing is that people get that second shot, on time if possible.

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About the Authors:

Courtney Friedman is a KSAT anchor and reporter. She has an ongoing series called Loving in Fear, confronting Bexar County’s domestic violence epidemic. She's also covered Hurricane Harvey, the shootings in Sutherland Springs and Santa Fe, and tornadoes throughout Texas. She’s a California native and proud Longhorn who loves calling SA home.