A vaccine vial on top of a half-yellow half-orange background.
Illustration: PGN

Leer en español

What you need to know

  • Fall boosters are expected to offer better protection against BA.5.
  • The new shots are just as safe as the original vaccines.
  • The updated boosters will be critical to preparing for a potential fall or winter surge.

Fall boosters are finally here. Last week, the FDA and the CDC signed off on the updated COVID-19 vaccine boosters. The modified doses are now being shipped out and administered at pharmacies, community health centers, and doctors’ offices around the country. Here is what you need to know about how these boosters are different and why we need them for the upcoming fall and winter.

How are the fall boosters different from our original vaccines?

The fall boosters developed by Pfizer and Moderna are bivalent vaccines, or vaccines that protect against more than one strain of a virus. In this case, the modified doses target the original COVID-19 strain and the BA.4/BA.5 Omicron subvariants. The goal of the fall boosters is to offer better protection against BA.5, which currently makes up nearly 90 percent of circulating COVID-19 variants in the U.S.

Who is eligible to receive an updated fall booster?

Pfizer’s 30-microgram fall booster is authorized for people ages 12 and older, while Moderna’s 50-microgram booster is authorized for adults only. There is no updated booster for kids ages 6 months to 11 years yet, but Pfizer confirmed that it is working on one for this youngest age group

The FDA says people can safely get an updated booster at least two months after their last shot. But to maximize effectiveness, doctors and immunologists recommend waiting four to six months after immunization or infection. A longer period between shots allows the body to produce a stronger immune response. However, people who are at high risk or who have an important upcoming event should consider getting their fall booster sooner.

Where can you get a fall booster?

The doses are being offered at pharmacies, community health centers, and doctors’ offices around the country. You can now schedule an appointment at CVS or Walgreens to receive the fall booster, or use Vaccines.gov to find sites near you offering the new shots.

Why do we need updated boosters?

The original COVID-19 vaccines continue to be effective against severe disease, but they do not offer strong protection against Omicron infection. As we saw during the Omicron wave last winter, a surge in infections inevitably leads to a rise in hospitalizations and deaths.

The updated boosters will ideally provide more targeted protection against BA.5 infection and severe disease. By decreasing the risk of infection, the new shots would in turn minimize the number of hospitalizations and deaths, especially among individuals who are immunocompromised. Scientists also hope that the updated boosters will provide longer-term immunity and broader protection against future variants.

Are the updated boosters safe and effective?

Federal health officials stress that the modified shots are just as safe as the original vaccines. The FDA did not require the updated boosters to go through the full authorization process, which includes human clinical trials, because the shots use the same foundation as the already authorized original vaccines. This sped-up process is similar to the one used for the flu vaccine, which is altered each year to target the strains most likely to be dominant.

The effectiveness of the updated boosters, however, is less clear. Since the modified shots did not go through human trials, there is no direct data on how well they work and what kind of immune response they trigger. Pfizer and Moderna presented promising data from animal trials to show effectiveness during the CDC advisory meeting this week.

Data from previously tested bivalent vaccines—which targeted the beta and BA.1 variants—also suggest that these types of vaccines have the potential to increase effectiveness against infection and trigger a more durable immune response.