Pfizer and BioNTech will supply 40 million doses of COVID-19 vaccine to COVAX, the worldwide campaign aimed at guaranteeing every nation has access to the treatment, reports said Sunday, citing the pharmaceutical companies and World Health Organization.

The effort, announced during a virtual meeting spearheaded by the Geneva-headquartered WHO, is viewed as very critical because Pfizer and BioNTech last month were granted emergency use authorizations from the world health body and the U.S. Food and Drug Administration.

Pfizer has finished enrolling children aged 12 and 15 in a study testing its COVID vaccine, as the company seeks to broaden the shot's use among different age groups.

Last month, Moderna also started a study to test its vaccine, which employs a similar technology as Pfizer's, in adolescents aged 12 to under 18.

The COVAX commitment, led by the WHO, Immunization and the Coalition for Epidemic Preparedness Innovations, and the GAVI vaccine alliance, approved deals for hundreds of millions of doses to immunize people in marginalized and lower to middle-income nations, but the inoculations have yet to start.

Its objective is to provide 2 billion doses of COVID vaccines to participating countries by the end of this year.

WHO Director-General Tedros Adhanom Ghebreyesus said that the vaccine program also expects 150 million doses of AstraZeneca's vaccine to become available for mass distribution around March this year.

Earlier this week, Ghebreyesus had criticized vaccine companies for seeking profit by prioritizing wealthier nations to buy up the available supply of the vaccines.

Lambasting rich countries for their "Me first" attitude, Ghebreyesus stressed that almost 40 million doses of the COVID vaccine had been given so far in only 49 higher-income regions.

Ghebreyesus said he hoped the vaccine deal would also encourage other governments to donate more of their Pfizer shots to support the fast distribution as Norway has.

"We share the mission of COVAX and are proud to work together so that developing nations have the same access as the rest of the world, which will bring us another step closer to ending this global pandemic," CNA quoted Pfizer chief executive officer Albert Bourla as saying in a statement.

Dr. Seth Berkley, chief executive officer of GAVI, called the deal a "major step" forward for equitable access to the coronavirus vaccines.

Dr. Anthony Fauci, U.S. President Joe Biden's chief medical adviser, on Friday said the U.S. plans to join the program. Biden's predecessor Donald Trump had suspended the funding to the WHO and announced a withdrawal process.