More than 100 of the world’s poorest countries have begun receiving vaccines for the coronavirus disease 2019 (Covid-19) through the World Health Organization’s COVAX program, a global effort to send millions of doses to developing nations, officials said Thursday.

The WHO said the COVAX facility has so far delivered almost 40 million vaccine doses across six continents, supplied by AstraZeneca, the Pfizer-BioNTech partnership and the Serum Institute of India.

Of the more than 100 countries COVAX has supplied with shots, 61 are among the 92 lower-income economies receiving vaccines funded through the Gavi COVAX Advance Market Commitment, officials said. Gavi is a vaccine alliance that aims to expand access to poorer nations.

The delivery milestone Thursday came 42 days after the first COVAX-supplied doses were delivered to Ghana on Feb. 24. Despite reduced supply in March and April, officials said COVAX expects to deliver doses to all participating countries that have requested vaccines.

“COVAX has given the world the best way to ensure the fastest, most equitable rollout of safe and effective vaccines to all at-risk people in every country on the planet,” WHO Director General Dr. Tedros Adhanom Ghebreyesus said in a statement.

The program expects to deliver at least 2 billion doses of vaccines in 2021, according to its latest supply forecast.

“The United States welcomes the news that COVAX has delivered safe and effective COVID-19 vaccines to 100 countries,” added U.S. Secretary of State Anthony Blinken. “The United States signaled our strong support for COVAX through an initial $2 billion contribution to Gavi.

“Through unprecedented partnerships among donors, manufacturers, and participating countries, COVAX has achieved extraordinary milestones in equitably distributing doses to the global community in record time,” he added.