Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases.Patrick Semansky | Bloomberg | Getty ImagesThe U.S. will remain a member of the World Health Organization under President Joe Biden, Dr. Anthony Fauci said on Thursday, and intends to join a global alliance that aims to deliver coronavirus vaccines to low-income countries.Speaking from Washington by videoconference one day after Biden was sworn into office, U.S. Chief Medical Advisor Fauci told the WHO’s executive board: “President Biden will issue a directive later today which will include the intent of the United States to join COVAX and support the ACT-Accelerator to advance multilateral efforts for Covid-19 vaccine, therapeutic, and diagnostic distribution, equitable access, and research and development.”The U.S. will also remain a member of the WHO, the United Nations health agency, and “fulfill its financial obligations,” Fauci said. It comes after former President Donald Trump announced in May that the U.S. would withdraw from the WHO, but the process wasn’t expected to be finalized until this July. Fauci said the Biden administration planned to work with the other 193 member states to help reform the group.”This is a good day for WHO and a good day for global health,” said WHO Director-General Dr. Tedros Adhanom Ghebreyesus.”We are all glad that the United States of America is staying with the family,” Tedros said via Twitter.WHO delegates “warmly welcomed” the decision, with many underlining their appreciation that the new administration would now seek to reengage with the international aid group amid the ongoing coronavirus pandemic.Fauci, America’s top infectious disease expert, accepted Biden’s offer to join his administration and serve as chief medical advisor last month. He will lead a U.S. delegation at the WHO’s annual meetings throughout the week.Trump vs. WHOTrump had repeatedly criticized the WHO for being what he perceived to be too “China-centric,” and denounced the amount of funding the U.S. allocated to the health agency in comparison to other countries.The U.S. was the largest single donor to the Geneva-based aid group in 2019. It reportedly contributed more than $400 million, accounting for roughly 15% of the WHO’s budget.The WHO is funded by a combination of members’ fees based on wealth and population and voluntary contributions.The WHO’s Tedros said in August that he hoped the U.S. would reconsider its decision to leave the organization. The problem was “not about the money,” he said, but rather about the lack of cooperation in the midst of the pandemic.— CNBC’s Noah Higgins-Dunn contributed to this report.