Doctors are also encouraged by data in the FDA briefing documents which suggests the Moderna vaccine can reduce the virus' silent spread.
Brown University professor and CNN medical analyst Dr Ashish Jha tweeted the Moderna breakthrough reduces asymptomatic infections by about 67 per cent after one dose.
"We don't know what happens after 2nd dose (yet) but as I have been saying, these vaccines likely reduce spread of asymptomatic disease. Now some evidence that is true."
Professor Eric Topol, of the Scripps Research Translational Institute, tweeted: "This is the best news of the day. Towards the vaccine avoidance of asymptomatic carriers, achieving mucosal immunity. The data aren't conclusive but support this key benefit."
He added that this was also seen in medical data on the AstraZeneca/Oxford University vaccine candidate.
There was also good news with pharmacists finding that some of Pfizer's vials contained enough for two extra doses - boosting coverage.
The FDA has also authorised an Australian-made antigen test - the first at-home coronavirus check people can buy without a prescription. Made by Ellume, it takes 20 minutes.
The positive news is too late for the 1.6 million people lost to the virus around the world. And 73.2 million global infections will mean long-term health impacts for many. Even as the cavalry arrives, the situations in the Northern Hemisphere and parts of Asia are worsening.
Even so, the vaccine programmes, which will be a dominant feature of life next year, are a chance for a collective boost after a bad 12 months.
In the US, the vaccine drive might inject more common purpose. It's a second chance to have a go at rebuilding public trust and unity. And the best approach the incoming Biden administration can take to dilute toxic political division is to improve people's lives.
Still, once again we are seeing piecemeal, individual country action on hoarding supplies and approving rollouts. Not having one reliable and independent body to approve vaccines in pandemic emergencies makes no sense.
Poorer countries will probably have to wait far longer for access to vaccines, unless big nations help them out. Wealthy nations so far have monopolised access to the first two vaccines and others will take longer to come on the market.
The World Health Organisation said on Thursday that vaccinations for Asia-Pacific countries that don't have their own independent deals won't get under way until mid to late next year.
New Zealand has acknowledged this situation by purchasing enough for our neighbouring territories of Tokelau, Niue and the Cooks - as well as Samoa, Tonga and Tuvalu, if they need it.
Long-haul vaccination programmes with Pfizer/BioNTech doses are under way in Britain and also in Canada, which will get the Moderna vaccine as well if the country's regulator approves it.
The European Medicines Agency has moved up a meeting to assess the Pfizer vaccine to next Tuesday. The meeting, originally planned for December 30, has been advanced to speed up vaccine distribution in the European Union, perhaps before the end of the year.
Overall, the vaccine progress will be a relief to populations everywhere, especially those still under coronavirus restrictions with Christmas still to get through.
It's hard not to feel sympathy for a Scottish man who went that extra mile for love in the time of Covid last weekend and ended up being sentenced to four weeks in jail for violating coronavirus rules.
Dale Mclaughlan, 28, jetskied across the Irish Sea to the Isle of Man to see his girlfriend. The four-and-a-half-hour trip then morphed into a 25km hike to her home.
He will at least have a story to tell the grandkids about the pandemic of 2020.
