Should You Mix COVID-19 Vaccines?

Key TakeawaysSome countries are recommending a “mix-and-match” vaccine approach for better COVID-19 protection.Current CDC guideline states that COVID-19 vaccines are not interchangeable.Health experts say getting a booster shot, whether it’s from the same vaccine maker or not, could offer extra immunity for vulnerable groups.

Key Takeaways

Some countries are recommending a “mix-and-match” vaccine approach for better COVID-19 protection.Current CDC guideline states that COVID-19 vaccines are not interchangeable.Health experts say getting a booster shot, whether it’s from the same vaccine maker or not, could offer extra immunity for vulnerable groups.

Several countries are recommending a “mix-and-match” approach in COVID-19 vaccinations.

Germany’s government encourages people who get a first dose of the AstraZeneca vaccine to get an mRNA vaccine, like Pfizer or Moderna, for their second dose, according to the Associated Press. Canada supports the same approach,The Washington Postreported.

TheAstraZeneca vaccineuses a modifiedadenovirus—one of the viruses that cause the common cold—to house genetic material from the SARS-CoV-2 virus. TheJohnson & Johnson vaccine, which is authorized in the U.S., works the same way.

The AstraZeneca vaccine is not yet authorized in the United States. Current guidance from the Centers for Disease Control and Prevention (CDC) states that COVID-19vaccines are not interchangeableexcept in “exceptional situations,” although some overseas residents have already tried mixing vaccines.

Will the AstraZeneca COVID-19 Vaccine Be Safe to Take?

Matt Collins, an author and marketing specialist who lives in Chile, initially received two shots of Sinovac-CoronaVac. He got a booster Pfizer shot when visiting family in Michigan over the July 4 weekend.

Nearly 56% of the population in Chile is fully vaccinated,yet the country is seeing a surge in case numbers.

“As I started talking to a lot of people in Chile, what I learned is that they had received the Sinovac vaccine, but were also getting sick,” Collins says. “That was a big factor in me getting a booster.”

Current studies present a range of efficacy rates for Sinovac, from about 50% to 90%, according toThe New York Times.

In contrast to the varying data on the Sinovac vaccine, the Pfizer, Moderna, and Johnson & Johnson vaccines available in the U.S. currently reveal more consistent efficacy rates when studied. According to CDC data,two doses of Pfizer or Moderna are about 94% effective at preventing COVID-19and one dose of Johnson & Johnson is 66.3% effective.

In the U.S., the CDC currently does not recommend additional doses. Recent studies showed that Pfizer’s and Moderna’s COVID-19 vaccines could offer long-lasting immunity, which means a booster shot may not be needed anytime soon.

Pfizer and Moderna COVID-19 Vaccines Could Produce Years of Immunity

VirologistAndrew Pekosz, PhD, tells Verywell that for those seeking a booster shot in the U.S., any of the FDA-authorized vaccines should offer extra immunity.

“Most data about vaccinations suggests that it probably doesn’t matter what you get as a booster,” he adds. “You can still stimulate those immune responses a little bit more efficiently and get to a good level of protection.”

Each initial vaccination gives the body a set of responses to fight off the virus, and a booster shot strengthens these immune responses rather than changing them, he adds.

What This Means For YouSeveral countries are recommending people who get their first dose of AstraZeneca vaccine to get a second mRNA COVID-19 vaccine, like Pfizer or Moderna. This practice is helpful for places that have limited vaccine access or uneven distribution. In the U.S., the CDC currently does not recommend additional doses or interchanging COVID-19 vaccines.

What This Means For You

Several countries are recommending people who get their first dose of AstraZeneca vaccine to get a second mRNA COVID-19 vaccine, like Pfizer or Moderna. This practice is helpful for places that have limited vaccine access or uneven distribution. In the U.S., the CDC currently does not recommend additional doses or interchanging COVID-19 vaccines.

As the Delta variant is now the dominant variant in the U.S., scientists may also need to consider whether it is more effective to develop a variant-specific booster, he says.

“That’s the critical question that needs to be addressed, whether or not we go back to the original formulation that we had and try to boost with that, or whether we change it to a spike protein that’s present in one of the variants that’s currently circulating,” he adds.

Tom Kenyon, MD, MPH, chief health officer at Project HOPE and former director of global health at the CDC, writes to Verywell that more research is needed to determine whether mixing vaccines will work.

“There is a theoretical possibility that using different vaccines could actually strengthen the immune response to different parts of the spike protein,” he says. “But we need to await further study results before allowing mixing vaccine doses."

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit ourcoronavirus news page.

2 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.World Health Organization.Chile situation.Centers for Disease Control and Prevention.Johnson & Johnson’s Janssen COVID-19 vaccine overview and safety.

2 Sources

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.World Health Organization.Chile situation.Centers for Disease Control and Prevention.Johnson & Johnson’s Janssen COVID-19 vaccine overview and safety.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

World Health Organization.Chile situation.Centers for Disease Control and Prevention.Johnson & Johnson’s Janssen COVID-19 vaccine overview and safety.

World Health Organization.Chile situation.

Centers for Disease Control and Prevention.Johnson & Johnson’s Janssen COVID-19 vaccine overview and safety.

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