Johnson famously prepared two newspaper articles arguing for and against Britain's departure from the European Union before leading the Brexit campaign in 2016.
Biden, who himself has routinely worn face coverings while campaigning and out in public, said that even as good news of a successful coronavirus vaccine trial has emerged, the single most effective thing we can do to stop the spread of Covid is to wear a mask."
Biden was projected as the winner of the bitterly contested November 3 election on Saturday by US media, though President Donald Trump has yet to concede.
The firing of Esper, who had clashed with Trump over his suggestion of using military personnel to quash civic unrest, comes a week after the US presidential election.
Trump has launched a slew of legal challenges, complained of vote fraud without offering evidence, and refused to concede after the major US television networks announced Biden's win.
Some of the United States' biggest and closest allies in Europe, the Middle East and Asia quickly congratulated Biden over the weekend despite Trump's refusal to concede.
"We noticed that Mr. Biden has declared election victory," China's foreign ministry spokesman Wang Wenbin.
Biden is due to meet with an advisory board co-chaired by former Surgeon General Vivek Murthy.
"Dealing with the coronavirus pandemic is one of the most important battles our administration will face, and I will be informed by science and by experts," Biden said.
Helme is a member of the populist, far-right Ekre party, which sits in a coalition with the Centre and Fatherland parties under Prime Minister Juri Ratas.
Helme told reporters he stuck by what he had said, but that he was resigning in protest at how his comments had been covered by Estonian media.
Akbar added that with the arrival of Biden the US and China are likely to cooperate to end the ongoing coronavirus pandemic, which would prove beneficial for Pakistan.
Imran says he is looking forward to Biden's Global Summit on Democracy & working with him to end illegal tax havens & stealth of nation's wealth by corrupt leaders
Pennsylvania was enough to get Biden over that halfway line. With leads in Georgia, Arizona and Nevada, he may well end up winning far more than needed - taking those three states would give him a total of 306.
Americans have been waiting longer than in any presidential election since 2000 to learn the winner, with counting slowed by a record number of mail-in ballots.
"The numbers tell us ... it's a clear and convincing story: We're going to win this race," Biden said.
In addition to Pennsylvania, Biden has pulled ahead in the southeastern state of Georgia, which has 16 electoral votes, but it remains too close to call.
President Donald Trump has imposed tariffs on French wines in a row over Airbus subsidies, threatened levies on Champagne and luxury handbags in a digital tax dispute.
Biden took a razor-thin lead over President Donald Trump in the battleground state of Georgia early on Friday.
The former senator from Delaware and Democratic hopeful currently has 253 electoral votes -- or 264 if the 11 electoral votes from the southwestern state of Arizona are included.
Donald Trump has amassed 214 electoral votes so far, and is still in contention in several states that would afford the Republican incumbent a path to reelection.
Two days after polls close, Democrat Joe Biden edged closer to victory in the U.S. presidential race on Thursday with only handful of states that will determine the outcome of the Election.
Democratic nominee Joe Biden has a slight edge over Republican President Donald Trump with 227 to 213 electoral votes. That leaves 98 electoral votes to be allocated, and possible paths to victory for both candidates. The winner needs to secure 270 votes.
“After a long night of counting, it’s clear that we’re winning enough states to reach 270 electoral votes needed to win the presidency,” Biden said. “I’m not here to declare that we’ve won, but I am here to report that when the count is finished, we believe we will be the winners.”
Trump’s campaign asked to intervene in a pending U.S. Supreme Court case over whether Pennsylvania, another key state that was still working its way through hundreds of thousands of mail-in ballots, should be permitted to accept late-arriving ballots sent by Election Day.
The Trump campaign has announced its intention to request a recount in the state, citing "reports of irregularities... which raise serious doubts about the validity of the result."