Some 172 countries are engaging with the COVAX facility designed to ensure equitable access to COVID-19 vaccines, the World Health Organization said on Monday, but more funding is needed and countries need now to make binding commitments.

Countries wishing to be part of the global COVAX plan have until Aug. 31 to submit expressions of interest, WHO officials said, with confirmation of intention to join due by Sept. 18, and initial payments due by Oct. 9.

WHO director general Tedros Adhanom Ghebreyesus said the facility was critical to ending the COVID-19 pandemic, and would not only pool risk for countries developing and buying vaccines, but also ensure prices are kept “as low as possible”.

“Vaccine nationalism only helps the virus,” he told a media briefing. “The success of the COVAX facility hinges not only on countries signing up to it, but also filling key funding gaps.”

COVAX is co-led by the GAVI vaccines alliance, the WHO and the CEPI Coalition for Epidemic Preparedness Innovations and is designed to guarantee equitable access globally to COVID-19 vaccines once they are developed and authorized for use.

It currently covers 9 candidate COVID-19 vaccines and its aim is to secure supplies of and deliver 2 billion doses across countries that sign up by the end of 2021.

“Initially, when there will be limited supply (of COVID-19 vaccines), it’s important to provide the vaccine to those at highest risk around the globe,” Tedros said.

He said this included health workers on the front lines of the pandemic, who were “critical to saving lives and stabilizing the overall health system”.