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Your Guide to the Bivalent COVID-19 Booster Vaccine

Contributor: Erica S. Shenoy, MD, PhD
7 minute read
Patient receives COVID booster shot

The Centers for Disease Control and Prevention (CDC) have approved and recommended updated bivalent COVID-19 vaccines from Pfizer and Moderna. These vaccine boosters protect against the original strain of COVID-19 and the Omicron variant, which is currently spreading in the United States.

Erica S. Shenoy, MD, PhD, a Mass General Brigham infectious diseases doctor, answers patients’ common questions about the bivalent COVID-19 booster.

Q: How is the COVID-19 bivalent booster different from past booster shots?

Shenoy: Bivalent vaccines protect against two different viruses or two strains of the same virus. In this case, the updated COVID-19 boosters target the original COVID-19 strain and the newer Omicron variants (Omicron BA.4 and BA.5). They better protect you from the type of COVID that is currently spreading than the original booster (also called the monovalent booster).

Q: Who can receive an updated booster?

Shenoy: If you’re age 5 and older, you can receive the new bivalent booster if:

  • You’ve received all vaccines in your primary vaccination series, and
  • At least 2 months have passed since you received your last COVID-19 vaccine dose (either your final primary series dose or an original monovalent booster dose)

The Pfizer bivalent COVID booster is approved for age 5 and above. The Moderna booster is approved for age 6 and above.

Right now, COVID-19 is spreading significantly across the country. We’re also getting into colder weather and holiday season where there’s just much more togetherness—so it’s a good time to get your booster to protect yourself and those around you from serious disease.

Erica S. Shenoy, MD, PhD
Infectious Diseases Doctor
Mass General Brigham

Q: When should I get my bivalent COVID-19 booster? Can I get my annual flu vaccine at the same time?

Shenoy: There’s no time like the present. I’d recommend getting your COVID-19 booster when you’re eligible and your flu vaccine now or within the next few weeks.

Let’s start with the COVID-19 booster: Right now, COVID-19 is spreading significantly across the country with some of the highest levels of transmission here in the northeast. We’re also getting into colder weather and holiday season where there’s just much more togetherness. So it’s a good time to get your booster to protect yourself and those around you from serious disease.

Sometimes people ask me what’s the perfect timing for the flu vaccine since they want to get the most protection for when flu season ramps up. In the U.S. that usually means January or February—but flu season is truly unpredictable!

Sometimes flu season can come early as it did this year in the Southern Hemisphere. If you’ve delayed getting your flu vaccine until now, I’d recommend trying to get it before the first or second week of November. That will give the vaccine enough time to kick in before the holiday season gets into full swing.

If you decide to get both at the same time, that can be a time-saver and very convenient. There’s no reason not to get both the same day. It’s safe to do so and can save you an extra visit to the pharmacy or your doctor’s office.

Q: Where can I get my bivalent COVID-19 booster vaccine?

Shenoy: To find a bivalent COVID booster location near you, visit one of the following sites:

You can also find an updated COVID booster location by texting your zip code to 438829 or calling 1-800-232-0233.

Mass General Brigham offers the updated booster vaccine at many primary care offices and some specialty offices during regularly scheduled office visits. We are also hosting several clinics that offer both flu and updated COVID-19 booster vaccines throughout the fall. Check our website to see which clinics have both the flu shot and the updated COVID-19 booster.

Mass General Brigham will also continue to distribute vaccines from our mobile community vans. Check the schedule to see if the vans will be near you.

Q: What are common side effects from the COVID-19 bivalent booster?

Shenoy: Reported side effects seem to be the same as the original vaccine. Side effects are usually mild and go away on their own. The CDC has some good guidance on simple things you can do to reduce the severity.

These include:

  • Drinking plenty of fluids
  • Getting plenty of rest
  • Moving the arm in which you receive the shot to reduce pain or swelling

Q: How long do you expect bivalent booster protection to last?

Shenoy: That’s a great question. We know that immunity (your body’s ability to resist the virus) wanes over time. But the strength of protection also depends on how the virus evolves and whether future variants escape the vaccine-induced immunity or not. I think we will start to see some emerging data on this as it collects over time.

Q: The CDC recently approved the use of bivalent COVID-19 vaccines for children ages 5 to 11. Can you tell us more about this?

Shenoy: This is an extension of the bivalent booster approved for older ages. The Food and Drug Administration (FDA) authorized the updated COVID-19 vaccines from Pfizer-BioNTech for children ages 5 through 11 years, and from Moderna for children and adolescents ages 6 through 17 years. Just like with older individuals, the updated boosters are meant to restore protection that has waned from prior vaccinations. These boosters specifically target the variants spreading now.

Q: Can I “mix and match” vaccines (for example, Pfizer with Moderna)? Or should my booster be the same as my first vaccine?

Shenoy: The CDC doesn't recommend mixing vaccine products for your primary series. However, you can get a different product for the updated booster, except for 5-year-old children, for whom the Pfizer updated booster is the only recommended booster. For people ages 6 and older, they can receive either Moderna or Pfizer as their updated booster. That can be different from what they received previously for their primary series or any doses of the monovalent booster.

Q: What about updated boosters for kids younger than 5?

Shenoy: The age recommendations are based on data presented to the FDA and the CDC. Those data take time to build up. It’s possible to see updated boosters expand to younger than 5, but we will have to watch and see. We also may see changes to the updated boosters if COVID variants evolve in a way that shows we need to broaden or change the make-up of the vaccine. Time will tell.

Headshot of Erica S. Shenoy, MD, PhD



Erica S. Shenoy, MD, PhD Erica S. Shenoy, MD, PhD
Infectious Diseases Doctor