Answers to questions about COVID-19 bivalent booster vaccines

The Centers for Disease Control and Prevention (CDC) encourages those eligible to receive the new bivalent COVID-19 booster vaccine.

"The bivalent booster vaccine is a new vaccine that provides protection against the original strain of COVID-19, as well as the two more recent variants, BA.4 and BA.5," says Nipunie Rajapakse, M.D., a pediatric infectious diseases physician with the Mayo Clinic Children's Center. "We recommend that anyone over 12 years of age who has already completed their primary vaccination series and who hasn't had a COVID-19 vaccine in the last two months get this new booster vaccine."

Dr. Rajapakse says the bivalent booster helps to augment protection against some of the more recent variants that were not well protected against with the original vaccine.

Benefit of bivalent boosters

The updated boosters are called bivalent because they protect against the original virus that causes COVID-19 and the omicron variants, BA.4 and BA.5. The previous boosters are monovalent because they were designed to protect against the original virus.

Variant means a mutation that occurs in the virus over time. BA.5 is responsible for approximately 80% of COVID-19 infections in the U.S.

"We know that the COVID vaccines have done a really good job of preventing serious illness, hospitalizations and deaths from COVID-19," says Dr. Rajapakse. "And as we've seen new variants emerge, we've seen that some of these variants can get around the immunity that was provided by the original vaccines. We know that once you get these booster vaccines, you again have good protection from serious illness, hospitalization and death from some of the more recent variants."

When to get the booster vaccine

You're encouraged to get your booster if it has been at least two months since you've received either:

• A final primary series dose
• The original (monovalent) booster

"The boosters released in September differ from the prior boosters available to the public. If you have not had a booster dose within two months, you should go out and get the new booster vaccine," says Dr. Rajapakse. "It will provide you with more varied immunity to the more recently circulating strains of COVID."

Herd or community immunity

Vaccination helps the person receiving the vaccine and others by not spreading the virus to those who may be vulnerable.

Another advantage of vaccination is working toward herd or community immunity.

Dr. Rajapakse explains the concept, "That occurs when most people in a population are immune or protected from infection. If you can't get the infection, you can't transmit it to someone else. And we know that when we have high levels of community immunity, that protects people who either are not vaccinated or are not eligible for a vaccine, or who might not mount the same response or protective response to the vaccine they received."

"The most common example would be someone with a weakened immune system. So even if they get the vaccine, they might not get as much protection as someone with a healthy immune system," says Dr. Rajapakse. "And all the people around them being vaccinated and protected helps to protect that person in that situation as well."

Learn more about COVID-19 boosters:

• Will the COVID-19 booster be like an annual flu shot?
• Q&A podcast: Updated COVID-19 boosters target omicron variants