Since the beginning of the year, the BA.2 variant of the coronavirus has spread around the world, leading to major outbreaks in Europe and China. BA.2, a subvariant of omicron, is already widespread in America and is set to become the dominant strain of the virus here next month.

The spread of the new omicron variant has led many to wonder if another round of boosters is needed. And now the Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) have weighed in, approving a second COVID-19 booster for some. Here’s what you need to know.

• Why is a second booster needed? It really comes down to the omicron variant, which spread like wildfire at the end of last year. The BA.1 and BA.2 variants are both more transmissible than Delta. Many studies have now shown that vaccine protections against the omicron variants wane over a short time—about four months, thus making a second booster a good idea for at-risk groups.
• Will a second booster work even better against the omicron variants? “Better” isn’t the right word. But as CNBC reports, according to a CDC study from February, protection against omicron-related emergency department visits and hospitalization fell to only 66% and 78%, respectively, four months after the first booster. But an Israeli study showed a fourth dose “restores antibody titers to peak post-third dose titers.”
• Who gets the second booster? The CDC says anyone over the age of 50 will be eligible to receive the second booster as well as certain immunocompromised individuals.
• When can I get the second booster? If you’re in one of the above groups, you can get the second booster shot four months after you received the first booster.
• What vaccine is used for the second booster? Your second booster will either be another does of Pfizer or Moderna.
• Will people below the age of 50 get a second booster? Right now they won’t and health authorities are remaining mum about future plans for now. However, it’s possible that lower age groups may be offered another booster in the fall, when infections could spike again, though that is not a given. And, of course, if there is a new variant before then, health authorities could choose to open a second booster shot to the larger population.
• Where can I get more information? Read the CDC’s Tuesday media brief.