Johnson & Johnson’s single-dose vaccine is safe for use, and the Food & Drug Administration identified “no specific safety concerns” in its analysis of the shot, the FDA announced Feb. 24,

The vaccine is about 66% effective at preventing moderate to severe COVID-19 and approximately 85% effective against more serious cases, according to an FDA briefing document for the upcoming advisory committee meeting on Feb. 26.

These numbers reflect efficacy after at least 28 days after vaccination.

Participants in the vaccine group experienced adverse reactions for 1 to 2 days after vaccination that those in the placebo group didn’t experience, including injection site pain (48.6%), headache (38.9%), fatigue (38.2%) and myalgia (33.2%). Younger participants reportedly experienced reactions more commonly. After 1 to 2 days, those reactions were generally resolved, according to the report.

As of Feb. 5, there were 7 COVID-19 related deaths in the study in the placebo group and no COVID-19 related deaths in the vaccine group. About 40,000 people participated in the Phase 3 trial.

The report is a step in the FDA’s evaluation of a third vaccine option for the U.S. after the Pfizer and Moderna vaccines currently being rolled out.

Independent advisers at the FDA will debate on Feb. 26 if the analysis is strong enough to approve the shot. According to the New Jersey COVID-19 Dashboard, 1,758,979 vaccine doses were administered by 9:03 a.m. on Feb. 24. Of those doses, 1,192,364 were first doses, and 566,441 were second doses.

If approved, the J&J vaccine will be the first single-dose vaccine available to guard against COVID-19.

A spokesperson for J&J did not return a request for comment.