In this file photo former Democratic presidential candidate Joe Biden speaks during a campaign event in Fort Lauderdale, Florida on October 13, 2020 AFP
US President-elect Joe Biden Monday hailed as a cause for "hope" the news that a Covid-19 vaccine developed by Pfizer and BioNTech was 90 percent effective -- but warned of a long battle still ahead.
"I congratulate the brilliant women and men who helped produce this breakthrough and to give us such cause for hope," Biden said in a statement, adding that he received advance notice of the announcement on Sunday night.
"At the same time, it is also important to understand that the end of the battle against COVID-19 is still months away," he added -- stressing the continued importance of mask-wearing for the foreseeable future.
He spoke as European stock markets and oil prices jumped on the vaccine announcement.
Pfizer and BioNTech said that according to preliminary findings, protection in patients was achieved seven days after the second of two doses, and 28 days after the first.
The companies said they expect to supply up to 50 million vaccine doses globally in 2020, and up to 1.3 billion doses in 2021.
US President Donald Trump also hailed the news, calling it "great" on Twitter.
Soaring coronavirus cases across the world have forced many millions of people back into lockdown, causing further damage to ravaged economies.
In the US cases have been surging across the country in recent weeks. Trump's defeat to Biden last week was blamed in part on his administration's response to the pandemic.
Also on Monday Biden named the scientists who will lead his administration's pandemic response, signaling his plans to prioritize Covid-19 from the outset.
The advisory board will be led by three co-chairs: epidemiologist and former Federal Drug Administration (FDA) commissioner David Kessler, former surgeon general Vivek Murthy, and Yale public health professor Marcella Nunez-Smith.
In addition, the board will have 10 members, ranging from immunologists and epidemiologists to biodefense experts and leading public health officials.
Among them is Rick Bright, the virologist who was ousted by the Trump administration in April from his post as head of the Biomedical Advanced Research and Development Authority (BARDA), the agency charged with developing a vaccine.
A month later he warned Congress that Trump had no "master plan" to fight the pandemic.
Covid-19 has left more than 237,000 people dead in the US, the worst death toll globally.
According to a Johns Hopkins University tracker, the number of new US cases has topped 100,000 every 24 hours for several days running, and is nearing 10 million in total -- despite Trump's claim the world's biggest economy is "rounding the corner".
Biden said the board will help shape his approach on the surge in cases across the country as well as ensuring a safe vaccine is distributed efficiently, creating a blueprint he will begin implementing on day one of his presidency.
Biden and Vice President-elect Kamala Harris will receive a joint virus briefing Monday in Wilmington, Delaware from their advisory team.
Biden will then deliver remarks on coronavirus and economic recovery.