New Omicron Bivalent COVID-19 Boosters: Efficacy, Safety, and Other Important Information

You may have recently read about new booster shots to protect against COVID-19. They have been updated to provide better protection against the Omicron subvariants BA.4/5, which is currently the dominant strain in the US. These recordings received an emergency use authorization from the U.S. Food and Drug Administration on August 31, 2022.

At MSK, we strongly encourage our patients to consider the updated booster vaccine as soon as they are eligible for the best possible protection against the Omicron subvariants of COVID-19.

Mini Kamboj

Mini Kamboj, Chief Medical Epidemiologist at Memorial Sloan Kettering Cancer Center, has answers to commonly asked questions about vaccinations.

What does it mean that these boosters are bivalent? How are they different?

The term “bivalent” means they target two strains of COVID-19: the original strain, which first emerged in the US in early 2020, and the Omicron subvariants BA.4 and BA. 5 that recently emerged in the summer of 2022. The news media has also referred to these updated boosters as “Omicron specific”.

These bivalent boosters are manufactured by Pfizer-BioNTech and Moderna using the same technology as the monovalent vaccines that have been administered to over 200 million people in the United States. They are mRNA vaccines and they work the same as the original vaccines but have been slightly updated for added protection against Omicron BA.4/5.

As the COVID-19 virus continues to evolve, it is important that vaccines keep up. This is not a new approach. Every year there are new dominant strains of influenza. Scientists are developing a seasonal flu vaccine that targets these strains. The FDA is planning the same for COVID-19 vaccines and has now taken an important first step: Scientists will periodically produce an updated vaccine so people have the best protection against strains that are spreading or are expected to spread.

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How effective are the bivalent Omicron boosters?

It is widely believed in science and medicine that these bivalent boosters work better in preventing Omicron BA.4/5 infection while maintaining strong protection against serious illness from all COVID-19 strains. Omicron subvariants are expected to continue circulating in the coming months, and improving protection against this variant is critical.

To assess the overall efficacy of bivalent booster vaccines, a clinical trial used a bivalent COVID-19 vaccine that targeted both the original COVID-19 strain and another Omicron subvariant called BA.1. The data from this study were evaluated by the FDA and led to emergency use approval for the new bivalent booster.

In the study, researchers found that individuals who received the bivalent BA.1 booster had a better immune response against the COVID-19 omicron subvariant BA.1 than those who received the original (monovalent) booster. The Moderna portion of the study looked at 600 adults ages 18 and older, while the Pfizer-BioNTech portion of the study looked at 600 people ages 55 and older. The results of the two studies were similar.

The FDA believes that the best course of action now is to approve this new bivalent booster targeting BA.4/5 instead of BA.1. By replacing the BA.1 component of the booster vaccine with a BA.4/5 component, we are trying to avoid another potential wave of infections this fall and winter. An independent CDC advisory committee endorsed this FDA recommendation on September 2.

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Are the Omicron bivalent boosters safe? how do we know

These vaccines work in the same way as the original COVID-19 vaccines and boosters and are manufactured using the same process. Because of this, there’s no reason to think they’ll be any less secure. In addition, previous clinical studies on bivalent booster vaccines show that people experience the same side effects as the monovalent vaccines.

To date, more than 610 million doses of the COVID-19 vaccine have been administered in the United States. Serious side effects are treatable and very rare.

It’s important to note that the FDA, CDC, and companies that make the vaccines have closely monitored safety data for primary and booster vaccines. This crucial work continues with these new bivalent boosters.

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Am I eligible to receive a bivalent Omicron booster vaccine?

There are some important eligibility rules for these new bivalent booster vaccines:

  • Complete your primary series. To receive this new bivalent booster vaccine you must have completed your first course of vaccination against COVID-19. (Check the CDC’s website for information on how many doses you need to complete your primary series.)

  • age matters. The bivalent booster from Pfizer-BioNTech is approved for people aged 12 and over. The bivalent booster Moderna is approved for people aged 18 and over.

  • Topped up before September 1st? You are still eligible. If you have received 1 or more booster shots, you are still entitled to a dual booster. If you have not received any booster shots yet, you are also eligible.

  • wait 2 months Whenever your last COVID-19 vaccination was, you must wait 2 months before receiving a bivalent vaccination.

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What about children under 12?

Children aged 11 and younger cannot yet receive a bivalent vaccination. However, children aged 5 to 11 who have received Pfizer’s vaccine can still receive a regular (monovalent) booster shot 5 months after their second dose of their primary series. The FDA has not yet approved a booster vaccine for children under the age of 4.

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What about people who have or have had cancer? Can they get the bivalent booster?

Yes. At MSK, we strongly encourage all of our patients to get vaccinated and boosted.

People who now have cancer or have had cancer may have a weakened immune system because of the disease or its treatment. Because of this, they are particularly vulnerable to severe COVID-19. These new bivalent booster shots offer another layer of protection over and above the shots and booster shots you may have received.

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What about people who are pregnant, trying to conceive, or breastfeeding? Can they get a bivalent booster shot? Should you?

Yes. People who are pregnant, expecting to become pregnant or are breastfeeding are entitled to a new bivalent booster dose. It is well established that primary COVID-19 vaccines and periodic (monovalent) booster doses are safe and effective for this group. There is no reason to believe that this will be different with bivalent boosters.

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Can I still get the regular (monovalent) COVID-19 booster shot? What if I just finished my first vaccination series?

no With the FDA approval of these bivalent boosters, they have also de-approved monovalent boosters for Pfizer-BioNTech (for people 12 and older) and Moderna (for people 18 and older).

The Pfizer-BioNTech and Moderna vaccines remain approved as primary vaccines for children aged 6 months to 11 years. The Pfizer-BioNTech vaccine remains approved for use as a booster dose in children aged 5 to 11 years.

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If the bivalent booster offers better protection, can I get it as a primary shot?

no The bivalent boosters have not yet been developed for this. They are currently designed for use as a booster vaccine, meaning they have only been studied in previously vaccinated individuals. In the coming months, the bivalent vaccine could be recommended as the primary series of COVID-19 vaccine once ongoing trials are completed.

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I recently got infected with COVID-19. Should I get the new bivalent booster? When?

Yes, it is recommended that people who have contracted COVID-19 should still receive the bivalent booster.

We know from previous research that primary immunization and booster doses after infection increase protection against future infections and serious illnesses. This also applies to bivalent booster vaccinations.

People who have recently become infected can wait 3 months to get their booster shot.

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Can I get the bivalent booster shot at the same time as my flu shot?

Yes. All COVID-19 vaccines (including boosters) are safe and effective when given with other vaccines. There is no specific time interval recommended between routine vaccinations and the COVID-19 vaccine. The most important thing is that you take both vaccines. Whether on the same day or on different days, that’s your choice.

When vaccinating on the same day, it is recommended to administer the vaccinations in separate arms.

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Should I get the same brand of bivalent booster as my other shots? Or can I mix and match between brands?

It is acceptable to mix and match if the booster is approved for your age group. You can switch brands again or stick with what you got in the past.

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I am entitled to the Omicron Bivalent Booster. when should i get it

You should take the bivalent booster as soon as possible. The variants targeted by the updated bivalent booster (Omicron BA.4/5) are expected to continue to circulate throughout the United States

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Can I get my bivalent booster vaccination from MSK? How do I make an appointment?

From September 21st you can plan your bivalent booster at MSK. We will update this article with a link to online scheduling.

For pediatric patients, you must call your child’s GP at MSK. A parent or legal guardian must be present to consent to their child’s vaccination. You cannot give your consent over the phone or electronically.

However, there is no need to wait for the vaccination with MSK. We encourage patients to use the following websites to find a location with available vaccines:


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