U.S. Food and Drug Administration (F.D.A.) staff endorsed the regulatory approval of Monderan's (MRNA  ) coronavirus vaccine candidate on Tuesday, bringing the shot one step closer to emergency use approval from the federal health agency. The vaccine could be approved for emergency use as soon as Friday.

F.D.A. staff determined that the clinical trial results presented by Moderna were "consistent with the recommendations set forth in F.D.A.'s Guidance on Emergency Use Authorization (E.U.A.) for Vaccines to Prevent COVID-19."

Moderna had submitted for an E.U.A. on November 30 after researchers completed their final analysis of the drugmaker's late-stage clinical trial on over 30,000 participants. Researchers concluded that Moderna's shot was 94% effective in preventing COVID-19 infection, and was well tolerated with only mild-to-moderate side effects recorded in the vaccine participant group. The most common side effects were on par with most common vaccines; symptoms included injection site pain, fatigue, headache, muscle pain and chills. Most severe reactions were more common after the second dose of the shot and resolved in about a week.

Notably, the F.D.A. stated that is recommends health care providers track cases of Bell's palsy, a condition that causes sudden freezing or weakness in facial muscles that requires medical attention to resolve, if the vaccine is approved for widespread public use. Based on the trial data, three Bell's palsy cases were present in the vaccine group while one developed in the placebo group. Staff stated that there is currently not enough data to link a causal relationship between the vaccine and the condition.

The staff endorsement released Tuesday is meant to brief the F.D.A.'s Vaccines and Related Biological Products Advisory Committee ahead of its meeting on Thursday to review the drugmaker's request for an emergency use authorization.

This group of independent medical advisors recommended the approval of the Pfizer (PFE  )-BioNTech (BNTX  ) vaccine last week, and are expected to approve of Moderna's shot as well. However, the F.D.A. makes the final regulatory decision.

Widespread acceptance of a coronavirus vaccine will ultimately decide how long the pandemic will last, both domestically in the United States and abroad.

According to a recent Gallup poll, 63% of Americans surveyed stated that they are will to take a coronavirus vaccine, rebounding towards the survey's previous high of 66% following the low point of 50% set in September. While progress is being made towards public willingness to be immunized, that percentage is still below the 75% to 80% federal officials estimate will be needed to achieve herd immunity, where enough of the population is immune to infection that the virus can no longer spread easily.

Gallup found that Americans are extremely sensitive to public and political opinion surrounding a coronavirus vaccine.