The countdown has begun for the U.S. Food and Drug Administration’s anticipated final approval of a coronavirus vaccine developed by U.S. pharmaceutical giant Pfizer and Germany’s BioNTech, shown to be 95% effective in preventing COVID-19.

The FDA is widely expected to authorize emergency use of the vaccine – possibly later Friday or Saturday – after a special panel of the agency voted for its approval Thursday.

The decision came as the United States recorded a one-day record of deaths from the coronavirus, with more than 3,100 lives lost in a single day earlier this week.

As of Thursday evening, the U.S. had recorded 15.5 million cases and more than 291,000 deaths, according to Johns Hopkins University data.

Of the 22 people on the FDA panel, 17 voted in favor of authorizing the vaccine, four voted no and one abstained on the question: “Based on the totality of scientific evidence available, do the benefits of the Pfizer/BioNTech COVID-19 vaccine outweigh its risks for use in individuals 16 years of age and older?”

The four panelists who dissented largely expressed concern about giving the vaccine to 16- and 17-year-olds. Teens younger than 18 were represented in small numbers in studies for the vaccine, and during the hours of deliberations, some scientists worried the effects on this age group weren’t known well enough.

The vaccine was approved after hours of deliberation on topics including allergic reactions to the vaccine recorded in Britain this week.

The FDA panel’s recommendation was hailed by President-elect Joe Biden.

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“Today’s recommendation by FDA's Advisory Committee that an Emergency Use Authorization be issued for the Pfizer-BioNTech COVID-19 vaccine is a bright light in a needlessly dark time,” Biden said in a statement Thursday.

"The integrity of science led us to this point,” the statement went on, expressing gratitude to the scientists and others who worked on the vaccine.

The U.S. government will immediately ship 6.4 million doses of the vaccine across the country, with front-line health care workers receiving top priority for the first inoculations.

The U.S. military will also prioritize its health care workers for its initial allocation of the Pfizer/BioNTech vaccine, which will be just under 44,000 doses.

A Pentagon spokesperson told reporters Wednesday that the military will start inoculations “within a day or two” after the FDA approves the emergency use authorization. The vaccinations will be voluntary at first but could become mandatory once the vaccine is fully licensed.

The Pfizer/BioNTech vaccine has jumped to the front of the line in the global effort to develop a vaccine against the novel coronavirus that causes COVID-19. Britain became the first Western nation to begin mass inoculations of the drug on Tuesday, just days after the government’s medical regulatory agency approved the drug.