The U.S. Food and Drug Administration on Wednesday authorized a booster dose of the Pfizer-BioNTech COVID-19 vaccine for those 65 and older and some high-risk Americans, paving the way for a quick rollout of the shots.

The booster dose is to be administered at least six months after completion of the second dose, and the authorization would include people most susceptible to severe disease and those in jobs that put them at risk, the FDA said.

A U.S. Centers for Disease Control and Prevention advisory panel could vote Thursday on the use of a third shot of the vaccine, an agency official said at a public meeting of the panel Wednesday.

President Joe Biden announced in August the government’s intention to roll out booster shots for people 16 and older this week, pending approval by the FDA and CDC.

Advisers to the FDA voted Friday to recommend COVID-19 vaccine booster shots for Americans 65 and older and those at high risk of severe illness, after overwhelmingly rejecting a call for broader approval.

The advisory panel said there was not enough evidence to support booster shots for all those 16 and older who had received a second dose at least six months earlier, and it also sought more safety data.

The agency could revisit the issue of additional shots for a broader authorization in the future. Top FDA members have been split on the need for boosters for the general population, with interim head Janet Woodcock backing them and some of the agency’s senior scientists arguing that current evidence does not support them.

Johnson & Johnson said Tuesday that a second shot of its COVID-19 vaccine increased its effectiveness in the United States against moderate to severe forms of the disease.

Information on booster doses of Moderna Inc.’s COVID-19 vaccine is just weeks away, President Joe Biden’s chief medical adviser, Dr. Anthony Fauci, said Sunday.

Some countries, including Israel and Britain, have already rolled out COVID-19 booster campaigns. The United States authorized extra shots for people with compromised immune systems last month, and more than 2 million people had already received a third shot, CDC data showed.