A sick Californian nurse made a desperate appeal for help.

She says the federal Centres for Disease Control had been unwilling, or unable, to test her for COVID-19. Her patients may have infected her. She may have infected others.

She had volunteered to help.

“I did this because I had all the recommended protective gear and training from my employer,” she wrote in an open letter. “I did this assuming that if something happened to me, of course, I too would be cared for.”

She was wrong.

The protective gear did not work. She is sick. But she’s not getting any treatment.

“I’m awaiting ‘permission’ from the federal government to allow for my testing, even after my physician and county health professional ordered it. I am a registered nurse, and I need to know if I am positive before going back to caring for patients.”

As of yesterday, the US had only identified some 300 cases. Only eight have so far recovered, and 17 have died.

The resulting death rate of 5.9 per cent is the world’s highest. But that is a statistical aberration: the numbers are simply incomplete.

Epidemiologists know the actual number of sufferers is likely to already be in the tens of thousands. They just can’t prove it.

That’s because the test kits tailored to identify this specific virus are unavailable. And the government-run CDC has been imposing strange conditions upon its distribution and use.

The National CDC would not initiate testing,” the Californian nurse wrote. “They said they would not test me because if I were wearing the recommended protective equipment, then I wouldn’t have the coronavirus … What a ridiculous and uneducated response from the department that is in charge of our health in this country.”

The CDC is facing intense scrutiny.

The production of US COVID-19 testing kits was botched. The production facility was contaminated. A large batch of the vital kits was found not to be properly functional.

So they had to be recalled.

Instead, local doctors have had to ship samples to the one CDC laboratory capable of testing for the disease. The Atlanta facility was soon swamped.

Exactly how many US citizens have been tested is unknown. The CDC has strangely ceased reporting such vital statistics after Vice President Pence took over as the health agency’s public face.

Earlier this week he promised “roughly 1.5 million tests” would be available by the end of this week. On Friday, he rolled that promise back: “We don’t have enough tests today to meet what we anticipate the demand going forward,” he said.

"This is the most frightening disease I've ever encountered in my career."

Richard Hatchett, the doctor leading efforts to find a vaccine for coronavirus, says it is much more lethal than normal flu. But a survey of regional health officials by The Atlantic reveals a total of only 1900 suspected cases tested.

This is against the tens of thousands that need such testing - every day.

Meanwhile, the virus had already jumped ship.