Moderna plans to have 100 to 125 million doses of its Covid-19 vaccine available in the first quarter of 2021, the vast majority of which will go to the United States, the biotechnology company announced Thursday.

Between 85 and 100 million of the doses will be distributed in the United States, with the rest of the world receiving the remaining 15 to 25 million, the Cambridge, Massachusetts-based company said in a statement.

Moderna also confirmed that it expects to have 20 million vaccine doses available in the US by the end of 2020.

The company has been working on its American supply and production chain for months, in preparation for the vaccine's expected emergency approval by US Food and Drug Administration (FDA).

For all countries outside the United States, production will take place in Switzerland.

US officials have said they plan to distribute 40 million vaccine doses by the end of the year, including those produced by Pfizer-BioNTech.

That would mean 20 million people vaccinated by the end of 2020, with each person requiring two doses.

The Moderna vaccine will be reviewed by an advisory committee of the FDA on December 17, and could be green lit for emergency approval soon after.

The FDA advisory committee meeting for the Pfizer-BioNTech vaccine, which was approved Wednesday by Britain for general use, will take place on December 10.

WHO looks at e-certificates for vaccination

The World Health Organization said it was considering introducing electronic vaccination certificates, as hopes for an end to the pandemic were boosted after Britain became the first country to approve use of a Covid-19 vaccine.

"We are looking very closely into the use of technology in this Covid-19 response and one of them is how can we work with members states towards something called an e-vaccination certificate," WHO Europe expert Siddhartha Datta told an online press briefing Thursday.

Introducing such a certificate, which would make it possible to identify and monitor people who have been vaccinated, has not been finalised and would have to be drawn up in accordance with national laws, Datta said.

It would not be an immunity passport, which is supposed to assure that its carrier is protected against the disease because they have been infected and recovered.

"We do not recommend immunity passports," said Catherine Smallwood, the WHO's senior emergency officer for Europe.

Tech-savvy Estonia earlier this year began testing an app that could serve as a kind of digital "immunity passport", allowing users with antibodies to show employers and others their reduced risk of spreading the coronavirus.

Britain on Wednesday became the first country to approve the Pfizer-BioNTech Covid-19 vaccine, and the European Medicines Agency is due to announce its decision on December 29 at the latest.

The WHO's Europe zone, which covers 53 countries including Russia, has recorded more than 19.3 million infections and more than 433,000 deaths since the start of the pandemic, according its data table, with 1.5 million cases recorded in the past seven days.

"Whilst we are seeing a slight decrease in the number of cases in western Europe, this does not mean the entire WHO European region faces an improvement in the epidemiological situation," said WHO Europe regional director Hans Kluge.

"The resurgence is moving eastward with the hardest-hit countries now in central and southern Europe," he said, calling on governments not to lower their guard in the fight against the pandemic.

In the event of a fall in cases, "consider scaling-up the public health infrastructure and preparing for the next surge," he said.

US ex-presidents, Biden ready to publicly receive vaccine

Former US presidents Barack Obama, George W. Bush and Bill Clinton as well as President-elect Joe Biden are volunteering to take a coronavirus vaccine on camera if it will help promote public confidence.

Obama, in an interview with SiriusXM radio, said he would be inoculated if top US infectious disease expert Anthony Fauci signs off on a Covid-19 vaccine.

"If Anthony Fauci tells me this vaccine is safe, and can vaccinate, you know, immunize you from getting Covid, absolutely, I'm going to take it," Obama said.

"I promise you that when it's been made for people who are less at risk, I will be taking it," he said.

"I may end up taking it on TV or having it filmed, just so that people know that I trust this science, and what I don't trust is getting Covid," Obama said.

Freddy Ford, Bush's chief of staff, told CNN the former president also wanted to help promote vaccination.

"First, the vaccines need to be deemed safe and administered to the priority populations," Ford told CNN.

"Then, president Bush will get in line for his, and will gladly do so on camera."

Angel Urena, Clinton's press secretary, told CNN the former president would also be up for getting a vaccine in public on television.

Later in the day, Biden told CNN in an interview that he, too, would be willing to be vaccinated in public after government approval of vaccines, specifically saying he would rely on Fauci to say it was safe.

"It's important to communicate to the American people it's safe," the 78-year-old said. "It's safe to do this."

He also lauded the three former presidents for their commitment, saying they had "set the model as to what should be done."

Vaccines developed by Pfizer-BioNTech and Moderna-NIH are expected to be approved by US authorities shortly.

A top science official said Wednesday the United States hopes to have immunized 100 million people by the end of February.