That's on top of the $766 million the country has already donated to the program, which is aimed at supplying some of the world's poorest nations with inoculations.
President Joe Biden at the meeting - his first multilateral engagement since taking office - will announce the U.S.is directing $4 billion Congress allocated to Gavi in December to help procure coronavirus vaccines for poor countries, the senior official said.
The Campaign's Senior Director Jenny Ottenhoff stressed that this uneccessary excess is the epitomy of "vaccine nationalism", noting that "Rich countries understandably hedged their bets on vaccines early in the pandemic but with these bets paying off in spades, a massive course correction is needed if we are going to protect billions of people around the world". It remains to be seen how fellow G7 members will respond to Biden's calls, as the United States refused to take part in the COVAX program under the Donald Trump administration.
The French president has called on the USA and Europe to back his proposal to share 4% to 5% of their coronavirus vaccine supplies, and in an interview with the Financial Times, said that German Chancellor Angela Merkel supports the idea.
Canada has been getting all its Pfizer doses from a company facility in Puurs, Belgium, and has experienced disruptions in supply.
The president, in his first national security memorandum last month, called for his administration to develop a framework to donate surplus vaccines once there is a sufficient supply in the US.
Biden begins dismantling Trump's 'Remain in Mexico' asylum policy
Biden said that these asylum seekers will be allowed into the USA pending the completion of their immigration court hearings.
COVAX hopes to provide vaccinations to at least 20% of the population in 92 of the world's poorest countries by the end of this year.
Other wealthy nations have also begun reserving large orders of vaccines, leaving poorer nations to rely on the COVAX initiative for their populations - or on countries such as China, India and Russian Federation, who have begun directly donating their state-produced vaccines to other nations.
The J&J vaccine is administered in a single dose and can be stored at normal refrigerator temperatures, a big selling point in countries with relatively weaker healthcare infrastructure.
Speaking ahead of tomorrow's virtual meeting - which he will chair with leaders from Canada, France, Germany, Italy, Japan and the US - Johnson will lay out the UK's G7 priorities to address the pandemic and improve global health collaboration.
After the virtual gathering on Friday, the USA administration confirmed that Mr Biden is not inviting Russian Federation to join the G7 group of world leaders.