This is bananas.

US researchers working frantically to test potential COVID-19 vaccines are facing a critical shortage of one essential resource — monkeys.

“Nationally, there is basically a big shortage,” Koen Van Rompay, an infectious-disease scientist at the California National Primate Research Center, told The Atlantic.

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Primate research in the country was already pricey and controversial — but the coronavirus pandemic has been particularly bad for the monkey business.

“We can’t find any rhesus [monkeys] any longer. They’ve completely disappeared,” Mark Lewis, the CEO of contract research firm Bioqual, told the magazine.

Rhesus monkeys are most widely used in research, according to The National Primate Research Centers.

The monkey deficit can be attributed to the fact that the virus crisis has created a massive demand for the animals, coupled with a drop in supply from China, the news outlet reported.

China provided 60 percent of the nearly 35,000 monkeys imported to the US last year but shut off exports after COVID-19 hit.

Making things even harder, monkeys that are infected with COVID-19 have to be kept in Animal Biosafety Level 3 labs — and the US has a limited amount of those kinds of labs.

Van Rompay told the mag he gets an influx of calls weekly from companies looking to test COVID-19 treatments at his California research center, which is sponsored by the National Institutes of Health.

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“I have to tell them, ‘I’m sorry, we are not allowed to start your research,’” he said.

The NIH is now deciding which studies can use national primate centers under a public-private initiative called Accelerating COVID-19 Therapeutic Interventions and Vaccines, The Atlantic reported.

Monkeys account for about 0.5 percent of the animals used in US biomedical research, but they typically come into play in the key last step before human clinical trials, according to the Atlantic.