The ADB said the loan would allow the government to purchase 40 million additional COVID-19 vaccine doses for eligible children and booster shots for adults.
The Philippines is aiming to fully vaccinate at least 54 million people, or nearly half of its 110 million population, before the year ends.
To reach that target, it plans to hold a second three-day mass vaccination campaign from Dec. 15. It has so far fully immunised 39.2 million as of Dec. 7.
New daily cases in the Philippines have stayed below 1,000 since Nov. 24, a sharp decline from the more than 20,000 peak in late September that strained the fragile health system in the Southeast Asian archipelago.
The Philippines' improving COVID-19 situation has allowed it to gradually reopen the economy and tentatively resume in-person classes.
(Reporting by Karen Lema; Editing by Ed Davies)