Can you combine COVID vaccines or boosters? What Scientists and Doctors Say


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There are three COVID-19 vaccines available in the United States. Moderna and Johnson & Johnson have emergency approval from the Food and Drug Administration, while Pfizer full FDA approval. While the question of when and if we all need boosters still hangs, you may be wondering: Can I get a different brand the next time I need a vaccination against the coronavirus?

Mixing COVID-19 vaccines is done in other countries and in the US with other vaccines. However, before issuing an official recommendation or the green light, US health officials need to determine whether the benefits of mixing different vaccine types outweigh the possible risks and consider the differences between vaccines.

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Although all three vaccines do the same thing (although they differ slightly in effectiveness), the way they work is a little different. Pfizer and Moderna are mRNA vaccines that teach our cells to make a specific protein and build immunity against a virus. Johnson & Johnson is a vector viral vaccine that uses a harmless virus to activate an immune response and tell our body what to fight against future infections. Both types of vaccines prepare our immune systems for COVID-19 infection, and neither coronavirus vaccine infects us with the actual coronavirus.

Whether you are eligible for a booster vaccination now, want to be prepared for a possible third vaccination in the future, or are making plans for your first COVID-19 vaccination, here’s what we now know about mixing different brands of vaccines.

I am now entitled to an additional dose of vaccine. Do i have to get 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 your COVID-19 vaccine, it is recommended that you receive another dose at least four weeks after your second vaccination. Examples of people currently qualifying include organ transplant patients, people being treated for tumors or cancer in the blood, people who have had a stem cell transplant, people with untreated or advanced HIV infection, and people with other conditions or who are taking medication that suppress their immune systems. If you’re not sure if you need one, talk to your doctor.

When you received Pfizer for your first vaccine, you should be given a third dose of Pfizer, and the same goes for Moderna. However, the CDC says you could get the other mRNA vaccine if you didn’t know what brand you received or if that brand wasn’t available to you. (Johnson & Johnson recipients who are immunocompromised are not included in this recommendation from the CDC.)

On Friday, an advisory committee to the FDA found that people 65 and over and those at high risk of COVID-19 would also benefit from a third shot of Pfizer. This is a different decision than the CDC’s recommendation for immunocompromised people and has not yet been officially accepted by the FDA or endorsed by the CDC. Currently it would only apply to a select group of people who were initially vaccinated with Pfizer.

What if I accidentally get a different recording?

In general, the CDC says it is preferable to delay the second dose because you are waiting for the right vaccine, as data on people who have received two different vaccines (called a “mixed series”) are limited than to get another vaccine 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 vaccination was Moderna, you will not need a third dose of either vaccine and will still be considered a fully vaccinated second dose two weeks after your vaccination of an mRNA vaccine according to the CDC.

If you received Pfizer or Moderna for the first dose, Johnson & Johnson for the second dose because you have a contraindication (an allergic reaction to your first dose or any other medical reason you should not be given another dose of your first dose) , According to the CDC, you are considered fully vaccinated two weeks after your Johnson & Johnson shot.


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Is it safe to mix and match?

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

But before scientists and public health officials can put on record recommending a mixed vaccine for the general population, they must determine that it is a safe practice, and that the benefits outweigh any potential risks.

“Receiving different types of vaccines has theoretical advantages because different parts of the immune system can be compromised for protection,” says Dr. Margaret Day, Medical Doctor and Co-Chair of Vaccines at the University of Missouri Health Care. “But medical research into antibody and T-cell responses, as well as safety and efficacy in trials, continues.”

However, information from outside the United States shows promise, 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, mixing vaccine types depends on what’s available.) In a study published in the journal Nature, researchers in Spain found that people who took one dose of AstraZeneca (a vaccine similar to Johnson & Johnson) and then one Pfizer doses appear to produce a higher antibody response than subjects who received two doses of AstraZeneca. (It’s 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 testing mixing 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 when public health officials determine that a mixed vaccination schedule or “heterologous priming” is safe and effective, it can open doors for people when they are eligible for booster injections or additional doses. It can also induce public health officials to make specific vaccination recommendations for specific groups. For example, in the UK, the National Institute of Health says that for people under 40 who are in poor health, “it is preferable to have the Pfizer / BioNTech or Moderna vaccine over Oxford / AstraZeneca”. due to AstraZeneca’s association with a rare but serious bleeding disorder in younger people (who have a lower risk of dying from COVID-19 without being affected by any other health condition). Germany issued a similar recommendation on mixing AstraZeneca with an mRNA vaccine.

Johnson & Johnson’s shot in the US has also been linked to the same rare but serious bleeding disorder, and the CDC says, “Women under the age of 50 in particular should be aware of the rare but increased risk of this adverse event, and they should be about Be aware of other available COVID-19 vaccine options that have not been seen to be at risk. “Should this group ever require a booster vaccination or an additional dose and available data show that a mixed series is safe, it can be assumed the CDC might recommend that people in this group receive a different vaccine the second time.

But isn’t vaccines already mixed in the US?

In San Francisco, some Johnson & Johnson recipients received an mRNA shot after the city created “shelter” for those who asked, although it did not change San Francisco health policy.

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 designed in this way based on the immune response it might elicit.

Day says that although different brands of vaccine are sometimes used, “one key difference is that data are available for review for these years”.

While research is ongoing for everything else, Day says the best you can do is just complete the COVID-19 vaccine series as is currently being reviewed.

“Ultimately, the absolute most important thing people can do today to protect themselves and their communities from COVID-19 is to get their first line of COVID-19 vaccines,” said Day. “We will be faced with questions about the best strategies for the first series vaccination and additional vaccinations and booster doses, and these answers will be available in a timely manner.”

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always contact a doctor or other qualified health care provider with questions about a medical condition or health goals.


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