GENEVA — The head of the World Health Organization says it and partners have agreed to a plan to roll out 120 million rapid diagnostic tests for the coronavirus to help lower- and middle-income countries make up ground in a testing gap with richer countries — even if it’s not fully funded yet.

At $5 apiece, the cost of the antigen-based rapid diagnostic test for which WHO issued an emergency-use listing last week, the program initially requires $600 million. It is supposed to get started as early as next month to provide better access in areas where it’s harder to get the PCR tests that are used often in many wealthier nations.

The rapid tests look for antigens, or proteins found on the surface of the virus. They are generally considered less accurate, though much faster, than higher-grade genetic tests, known as PCR tests. Those tests require processing with specialty lab equipment and chemicals. Typically that turnaround takes several days to deliver results to patients.

WHO Director-General Tedros Adhanom Ghebreyesus hailed the program as “good news” in the fight against COVID-19.

“These tests provide reliable results in approximately 15 to 30 minutes, rather than hours or days, at a lower price with less sophisticated equipment,” he told a news conference in Geneva. “This will enable the expansion of testing, particularly in hard-to-reach areas that do not have lab facilities or enough trained health workers to carry out PCR tests.”

“We have an agreement, we have seed funding and now we need the full amount of funds to buy these tests,” he said, without specifying.