Can You Mix and Match COVID-19 Boosters?

Health officials recommend booster shots for most Americans who have received two doses of an mRNA COVID-19 vaccine. You can get a booster if it's been at least 5 months since you completed the original two-shot series.

Guidance on vaccine boosters from the Centers for Disease Control and Prevention (CDC) lets you choose which vaccine brand to get for your booster. You do not have to choose the same brand you received for your initial vaccine series. If you originally got the Pfizer vaccine, for example, you can get Moderna as your booster.

If you're immunocompromised, the CDC recommends an initial series of three mRNA vaccines given three and four weeks apart. If you are over the age of 18, you should get a booster shot three months after completing the series. You may be immunocompromised if:

• You have a condition that causes moderate or severe primary immunodeficiency
• You are taking medications that suppress the immune system
• You are being treated for cancer
• You have advanced HIV or HIV that is not being treated
  

The CDC does not recommend mixing brands for your primary vaccine series. However, you can mix and match brands for the booster.

What about Johnson & Johnson?

If you received the Johnson & Johnson vaccine, you can get a booster 2 months after receiving your first shot. The CDC recommends boosting with one of the mRNA vaccines, either Pfizer or Moderna.

For most people, the CDC doesn't recommend Johnson & Johnson as either the primary or booster vaccination. This is because there is a higher risk of serious adverse reactions with this vaccine.

There are certain exceptions, however. For example:

• If you've had a severe reaction to one of the mRNA vaccines
• If you are allergic to one or more ingredients in the mRNA vaccines
• If you don't have access to an mRNA vaccine
• If you know the risks but have a personal preference for the Johnson & Johnson vaccine
  

If you do choose to receive the Johnson & Johnson vaccine as your booster, you should get it at least two months after your first Johnson & Johnson vaccine or five months after your first two mRNA vaccines.

There May Be Some Benefits to Mixing and Matching

Research suggests that booster mixing can induce stronger immune responses.

A UK-based study, published in The Lancet, found that mixing doses of the AstraZeneca vaccine with an mRNA vaccine produced a stronger immune response compared with two doses of AstraZeneca.

Another research study, published in Nature Medicine, found similar results. When Pfizer or Moderna vaccines were used as a second dose to AstraZeneca, it led to a stronger immune response when compared with two doses of AstraZeneca, the study found.

For people who received Pfizer as their primary series, a Moderna booster may be preferable to another Pfizer. In phase two of The Lancet study, researchers found that two doses of Pfizer followed by a Moderna booster induced a stronger immune response than two doses of Pfizer and a Pfizer booster.

Ultimately, though, it is more important to get boosted than it is to wait for the perfect combination of primary and booster vaccines. If the booster you want isn't available, it's fine to get a different one. All combinations of the vaccines that are available in the United States provide good protection.

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 our coronavirus news page.