Can you mix and match vaccines or COVID boosters? What scientists and doctors say

There are three COVID-19 vaccines available in the United States. Moderna and Johnson & Johnson have Emergency Use Clearance from the Food and Drug Administration, while Pfizer has full FDA approval. As the question of when and if we’ll all need recalls continues to arise, you may be wondering: can I get a different brand the next time I need a coronavirus vaccine?

The mixing of COVID-19 vaccines is done in other countries, and it has been done in the United States with other vaccines. But before making an official recommendation or giving the go-ahead, health officials in the United States must determine whether the benefits of mixing different types of vaccines outweigh the potential risks, if any, as well as the risk. take into account the differences between vaccines.

For starters, although all three vaccines have the same effect (although their effectiveness varies slightly), how they work is a little different. Pfizer and Moderna are mRNA vaccines, which teach our cells to make a specific protein and boost their immunity against a virus. Johnson & Johnson is a viral vector vaccine, which uses a harmless virus to activate an immune response and tell our bodies what to fight for in future infections. Both types of vaccines prepare our immune systems for infection with COVID-19, and neither of the coronavirus vaccines infect us with the true coronavirus.

Whether you qualify for a booster now, want to prepare for a potential third vaccine in the future, or plan to receive your first COVID-19 vaccine, here’s what we know now about the mix of different vaccine brands. .

I am eligible for an additional dose of vaccine at this time. Should I have the same?

If you are “moderately or severely immunocompromised,” according to the Centers for Disease Control and Prevention, and have received Pfizer or Moderna as a COVID-19 vaccine, it is recommended that you receive another dose at least four weeks after your second injection. Examples of currently eligible people include patients who have had an organ transplant, people who are being treated for tumors or cancer in the blood, people who have had a stem cell transplant, people with an infection. untreated or advanced HIV and people with other conditions or who take medicines that weaken their immune system. If you are unsure whether you need it, talk to your doctor.

If you received Pfizer for your initial vaccine, you should receive a third dose of Pfizer, and the same goes for Moderna. However, the CDC says that if you don’t know which brand you received or if that brand isn’t available to you, you can get the other mRNA vaccine. (Johnson & Johnson immunocompromised recipients are not included in this CDC recommendation.)

Friday, an advisory committee to the FDA found that people aged 65 or older and those at high risk of COVID-19 would also benefit from a third injection of Pfizer. This is a different decision from the CDC’s recommendation for immunocompromised people, and it has not yet been formally accepted by the FDA or approved by the CDC. At this time, this would only apply to a select group of people initially vaccinated with Pfizer.

What if I had a different shot by accident?

Typically, the CDC says that because the data on people who have received two different vaccines (called a “mixed series”) is limited, it’s best to delay getting your second dose because you’re waiting for the right vaccine. rather than getting a different vaccine at the recommended time. But if there was any confusion at the clinic or if you accidentally received Pfizer for the second dose when your first injection was Moderna, you do not need a third dose of either. vaccines and you are still considered fully vaccinated two weeks after your second dose of an mRNA vaccine, according to the CDC.

If you received Pfizer or Moderna for the first dose, then Johnson & Johnson for the second dose because you have a contraindication (an allergic reaction to your first dose or some other medical reason why you should not receive another dose of your first dose), you’re considered fully vaccinated two weeks after your Johnson & Johnson injection, according to the CDC.

Is it safe to mix and match?

The fact that the current guidelines allow people currently eligible for an additional COVID-19 vaccine to obtain a dose of Pfizer if Moderna is not available, and vice versa, is likely due to the fact that scientists have determined that the benefits a third dose of coronavirus vaccine (protection against serious illness) for some people outweigh the unknown risks that may arise from receiving another type of vaccine.

But before scientists and public health officials can officially recommend a mixed series vaccine for the general population, they must determine that it is a safe practice and that its benefits outweigh any potential risks. .

“There are theoretical advantages to receiving different types of vaccines, as different parts of the immune system can be affected for protection,” says Dr. Margaret Day, physician and vaccine co-chair at the University of Missouri Health Care. . “But medical research is ongoing on antibody responses and T cell responses as well as the safety and efficacy of the tests.”

Information from outside the United States shows promising efficacy, however, and other countries have allowed people to receive two different vaccines, including Germany, Canada, Sweden, France, Spain and Italy, according to the New York Times. (In some cases, the mix of vaccine types depends on what’s available.) In a study published in the journal Nature, Spanish researchers found that people who received a dose of AstraZeneca (a vaccine similar to Johnson & Johnson) and then received one dose of Pfizer appear to produce a higher antibody response than people who receive two doses of AstraZeneca. (It is not clear whether this group had a higher immune response than people who received two doses of Pfizer.)

In the United States, the National Institutes of Health and the National Institute of Allergies and Infectious Diseases announced in June a study that tests the mixture of different COVID-19 vaccines. People in the study who received either Johnson & Johnson, Moderna, or Pfizer will receive an additional dose of Moderna.

When or if public health officials determine that a mixed or “heterologous priming” vaccination schedule is safe and effective, it can open doors for people to gain access if they become eligible for booster injections or injections. additional doses. It may also prompt public health officials to make certain vaccine recommendations for specific groups. In the UK, for example, the National Institute of Health says that for people under 40 who do not have a health problem, it is “better if you have the Pfizer / BioNTech or Moderna vaccine instead of ‘Oxford / AstraZeneca’. due to AstraZeneca’s link to a rare but serious blood clotting disorder in young people (who have a lower risk of dying from COVID-19 without the influence of another health problem). Germany has issued a similar recommendation for mixing AstraZeneca with an mRNA vaccine.

Johnson & Johnson’s injection in the US has also been linked to the same rare but serious blood clotting disorder, and the CDC says: “Women under 50 in particular should be aware of the rare but increased risk of this adverse event. , and they should be aware of other available COVID-19 vaccine options for which this risk has not been observed. If a booster or extra dose is needed for this group and the available data shows that a mixed series is safe, it may be safe to assume that the CDC might recommend that people in this group receive a different vaccine. the second time. .

But isn’t the vaccine mixing already happening in the United States?

In San Francisco, some Johnson & Johnson beneficiaries went ahead and received an mRNA injection after the city made an “accommodation” for those who requested one, although that did not change the situation. health policy in San Francisco.

The Ebola vaccine, manufactured by Johnson & Johnson, uses a mixed dose approach. According to EU Research and Innovation magazine, the two-part vaccine is made up of two slightly different technologies and was developed this way because of the immune response it could produce.

Day says that while sometimes different brands of vaccine are used, “a major difference is having years of data available for review for these.”

While the research for everything else is underway, Day says the best thing to do is just complete the COVID-19 vaccine series as it is currently being reviewed.

“Ultimately, the absolutely most important action people can take today to protect themselves and their communities from COVID-19 is to get their first set of COVID-19 vaccines,” Day said. “We will be faced with questions about the best strategies for the initial series vaccination and additional vaccinations and booster doses, and those answers will become available in time.”

The information in this article is for educational and informational purposes only and is not intended for health or medical advice. Always consult a doctor or other qualified healthcare professional with any questions you may have about a health problem or health goals.