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The US recently gave the all-clear to mix booster shots of one COVID-19 vaccine with other brands of the shot. Here’s why that’s safe and actually more effective. 

MICHIGAN—So you got your COVID-19 shot earlier this year but qualify for a booster shot. Is it okay to get a new type of vaccine? In a promising breakthrough from scientists, we now know the answer to that question is “Yes.”

That change is because a pair of US health departments Ok’d mixing and matching COVID-19 vaccines, saying that evidence supports doing so without any health consequences. 

This change doesn’t apply to everyone, and it also isn’t yet necessarily recommended by the Centers for Disease Control and Prevention or US Food and Drug Administration. But both agencies have said it’s OK to combine any combination of COVID-19 vaccines. 

“I don’t think there are any losers here,” Kathryn Edwards, a professor of pediatrics at Vanderbilt University Medical Center, told The Wall Street Journal. “Whether you get the same vaccine or a different one, it’s going to boost your immune response.”

Who Does This Affect?

Most people who have been vaccinated are affected by the recent booster shot expansion. Those who received Pfizer or Moderna vaccines are eligible to receive a booster shot six months after their initial shot if they’re 65 or older, live in a nursing home, or have several other factors. 

Boosters are allowed for anyone 18 and older who are at increased risk due to where they work or if they have other health issues. 

People who received Johnson & Johnson vaccines have been encouraged to get COVID-19 booster shots at least two months later because that vaccine hasn’t been proven to be as effective as the other two options. 

What Changed? And Why Does It Matter?

Some people who had previously received Pfizer COVID-19 vaccines were already eligible for a booster shot. But now, that eligibility expands to include some people who received Moderna and Johnson & Johnson brand vaccines, as well. 

The big news though is that the Centers for Disease Control and Prevention (CDC) is now allowing the mixing and matching of vaccines. The US Food and Drug Administration had previously okayed the booster expansion before the CDC gave its final approval on Oct. 21. 

“We are constantly learning about this virus, growing the evidence base and accumulating more data,” CDC Director Dr. Rochelle Walensky said at a panel discussion where the announcement was made, according to The Associated Press

Officials moved toward giving the all-clear for mixing COVID-19 vaccines with booster shots because evidence suggests it’s safe but also because it could be integral for those eager to get their booster shots. The flexibility created by expanding COVID-19 booster shots could make it easier to find a booster shot while giving health care providers additional flexibility when offering booster shots to patients, reports The Washington Post

It also means COVID-19 booster shots are more accessible to millions of more Americans. 

“It just could potentially speed things up,” said Jeanne Marrazzo, the director of the division of infectious disease at the University of Alabama at Birmingham. 

Is It Safe? 

All accounts indicate that getting shots containing two different types of COVID-19 vaccine is safe. Health experts have reported that there is no evidence to suggest getting two different vaccines caused any harm, and a recent study that followed people who had two COVID-19 vaccine types did not report any adverse reactions, according to The Wall Street Journal.

Some experts have said that data on the subject is still shallow. Only a small number of people were involved in the original study. But experts believe that with the vaccines being independently safe, mixing and matching shouldn’t present any problems. 

“We know that, in general, all of these vaccines are extremely safe,” David Dowdy, an epidemiologist at the Johns Hopkins Bloomberg School of Public Health, told The Washington Post. “So there’s no reason to think that there would be any problem with [mixing and matching].”