WASHINGTON (CBS News) — Millions of Americans as young as 12 could soon be able to get a booster shot of COVID-19 vaccine, after the Food and Drug Administration announced Monday that it has authorized third doses of Pfizer-BioNTech’s shot for that age group.

The FDA also said it would allow for children as young as 5 with compromised immune systems to get an additional shot. And the agency shortened the amount of time between a person’s second dose of the Pfizer vaccine and being eligible for a booster to five months instead of six months for all age groups.

“Based on the FDA’s assessment of currently available data, a booster dose of the currently authorized vaccines may help provide better protection,” especially against the Omicron variant, said Dr. Peter Marks, the FDA’s top vaccines official.