(NBC News) -- The Biden administration announced Friday that the U.S. is releasing $4 billion, already approved by Congress, to distribute vaccine to poor countries.
So far 130 countries haven't received any vaccine.
New variants of COVID-19 have appeared in 1,300 people in 42 states.
Pfizer admits its vaccine may be less potent against the South African strain.
"We are preparing for the possibility that there might need to be a change in the vaccine later," Pfizer Chief Scientific Officer Philip Dormitzer says.
Meanwhile, the U.S. is set to officially rejoin the Paris Climate Accord, the worldwide agreement that former President Trump pulled out of on his first day in office.
John Kerry, President Biden's Special Envoy for Climate, will co-host on Friday a global engagement summit focused on sustainability, including limits on global emissions.