Bivalent Boosters

UPDATED Octobe 21, 2022

The Food and Drug Administration (FDA) authorized bivalent formulations of the Pfizer and Moderna vaccines for COVID-19 as boosters. The new bivalent boosters are expected to provide increased protection against the omicron variant circulating now and are recommended for everyone who is eligible. Here’s what you need to know:

What is a bivalent vaccine?
A bivalent vaccine works by stimulating an immune response against two parts of the virus, rather than just one part. By targeting more than one part, the vaccine is more likely to remain effective when the virus undergoes change (mutates) to different forms (variants). The new bivalent boosters cause your cells to produce a protein found on the original SARS-CoV-2 virus causing COVID-19 and another protein found only on the Omicron BA.4/5 variants. The BA.4/5 variants are expected to be the primary strains to remain circulating throughout the fall and winter. Using multivalent vaccines  to protect against multiple virus strains has been in use for many years. Many flu vaccines protect against as many as four strains and are known as quadrivalent flu vaccines.

Who is eligible?
To be eligible, you must:

1. Be at least 5 years old. The Pfizer is available for those 5 and older. Moderna is available for those 18 and older.
2. Have received the primary series of vaccination for COVID
3. Have received your final dose of COVID vaccine, whether as one of the primary series or a booster, at least 2 months ago

Can I get a bivalent vaccine without having received my initial monovalent vaccines?
No. Monovalent vaccines, which include the component designed to fight the original COVID strain alone, will continue to be used for those seeking their initial vaccinations for COVID. The new bivalent vaccines are single-dose boosters and can only be provided to those who already received their first two shots.

Can I still get a monovalent vaccine as a booster?
With this introduction of the bivalent vaccines, monovalent boosters are no longer authorized as boosters for those 5 and older. 

Are the side effects worse for bivalent vaccines?
Side effects are expected to be similar to those experienced with the original monovalent vaccines.

If I have had COVID recently, how soon after symptoms clear up can I get a bivalent booster?
There are no clear data regarding the optimum time to be boosted after testing positive for COVID. I typically recommend 30 – 90 days, based on studies of waning antibody titers after recovering from COVID. There are no risks to receiving a booster shortly after infection.

I am eligible for a bivalent booster. Where and when can I get mine?
Southwestern Vermont Medical Center expects to receive bivalent boosters by the middle of next week and hopes to begin administering them on Tuesday, September 13, depending on supply, at the COVID Resource Center. Hours of operation are 8 a.m. – noon Tuesday and Thursday. Bivalent boosters will not be available at other SVMC practices for a few weeks or months.

Trey Dobson, MD, is chief medical officer at Southwestern Vermont Medical Center, part of Southwestern Vermont Health Care, in Bennington and an emergency medicine physician at Dartmouth Health.