The Food and Drug Administration’s staff released a briefing document on Wednesday endorsing Johnson & Johnson’s one-shot coronavirus vaccine as safe and effective.

An FDA advisory panel will meet Friday to review the briefing document and vote on whether to recommend an emergency use authorization (EUA). The FDA could then issue the (EUA) as soon as this weekend, clearing the way for distribution in the U.S. to begin.

The shot was found to be 66.9% effective against moderate to severe/critical COVID-19 cases 14 days after vaccination, and 66.1% effective after 28 days. Against severe/critical cases, the vaccine was 76.6% effective after 14 days and 85.4% effective after 28 days.

• A large clinical trial showed no COVID-19 hospitalizations or deaths 28 days after patients received the vaccine.
• “The analysis supported a favorable safety profile with no specific safety concerns identified that would preclude issuance of an EUA,” FDA staff wrote.

The FDA analysis also offered a breakdown of the efficacy of the vaccine in Brazil and South Africa, where more contagious variants of the coronavirus variants have been dominant.

• United States:
  • Moderate to severe/critical: 72%
  • Severe/critical: 85.9%
• South Africa:
  • Moderate to severe/critical: 64%
  • Severe/critical: 81.7%
• Brazil:
  • Moderate to severe/critical: 68.1%
  • Severe/critical: 87.6%

Unlike Moderna and Pfizer’s vaccines, which are the only two candidates that have received EUAs, the J&J vaccine is administered as a single dose and does not need to be stored at ultra-low temperatures — meaning the logistics for mass distributions would be far simpler.

The U.S. government has struck an agreement with J&J to provide 100 million doses by the end of June, but only 2 million to 4 million doses are expected to be ready for immediate shipment after FDA authorization, according.

• More than half of the J&J doses sold thus far are destined for the developing world, with 500 million doses purchased by the global COVAX initiative and 120 million by the African Union.