The World Health Organization on Monday expects to receive pledges from nations around the world for its plan to development and equitable distribution of a COVID-19 vaccine for all. So far, 172 countries have expressed early interest in the plan, named COVAX, including Canada, Norway, South Korea and Britain, but the W.H.O. stressed earlier this week that the project needs more funding in order to deliver its promises.

The COVAX facility plan is currently the only global initiative to ensure COVID-19 vaccines are available worldwide and distributed to both rich and poor in an equal manner. The plan is co-led by the W.H.O., the GAVI Vaccine Alliance, and the CEPI Coalitions for Epidemic Preparedness Innovations. Countries wishing to join COVAX have until Aug. 31 to submit expression of interest. They will then be asked to confirm their agreement by Sept. 18 and begin making initial payments by Oct. 9.

"Vaccine nationalism only helps the virus," W.H.O. Director General Dr. Tedros Adhanom Ghebreyesus warned in a recent press conference, quoted by Reuters. "The success of the COVAX facility hinges not only on countries signing up to it, but also filling key funding gaps."

The global initiative has so far signed up nine developing vaccine candidates. The plan sets out to obtain and deliver 2 billion doses of at least one safe and effective vaccine by the end of 2021 across all countries who join.

Meanwhile, the United States, Britain, Japan and the European Union have made their own private vaccine deals, something the United Nations has warned member countries against since it may short supplies due to global demand. If other countries follow that lead, it may undue the W.H.O.'s plan entirely.

In the United States, the Centers for Disease Control and Prevention Director Dr. Robert Redfield is already warning that a proven safe and effective vaccine, that is authorized by the Food and Drug Administration for public use, will likely be in short supply in the beginning.

"At first, there will likely be a limited supply of one of more of the COVID-19 vaccines, because limited doses will be available," Redfield told reporters, quoted by CNBC. "It's important that the early vaccines are distributed in a fair, ethical and transparent way."

The U.S. has invested over $10 billion in six vaccine candidates-- developed by the companies AstraZeneca (AZN  ), BioNTech (BTNX  ), GlaxoSmithKline (GSK  ), Johnson & Johnson (JNJ  ) Pfizer (PFE  ), Moderna (MNRA  ), Novavax (NVAX  ) and Sanofi (SNY  )--through its initiative Operation Warp Speed. The Trump administration's goal is to development and distribute 300 million doses of at least one safe and effective vaccine by January 2021.

"We don't know exactly how many doses we're going to have. We don't know at what time, you're going to have those doses as we approach the end of the year," Redfield added, quoted by CNBC.

The C.D.C.'s Advisory Committee on Immunization Practices, alongside other health think tanks, developed proposed guidelines earlier this week in a presentation on vaccine prioritization. As in the proposal, the agency is most likely to first call for vaccine distribution for health care workers, as well as other vulnerable populations like those with underlying health conditions in its official guidance.