Confirmed cases of coronavirus in California swelled to 3,894 on Thursday, up from 2,662 – alarming state officials who say that the rate of infection is now on par with that of New York, the worst-hit state in the US.

At this rate, they added, cases could overwhelm hospitals in California’s largest cities in a matter of weeks.

“I suspect that it will get worse in California. I can’t imagine that it wouldn’t. The writing is on the wall,” Dr Peter Chin-Hong, professor of medicine and an infectious disease specialist at the University of California San Francisco, said on Thursday.

“Hopefully we won’t see the kind of surge cases they’re seeing in New York right now where they’re running out of ventilators and ICU beds and having to open up stadiums and dormitories to house the ill,” he added.

By Thursday morning, with more than 1,200 additional cases confirmed, it appeared that the officials’ worst fears were being realised. The case numbers increased at a rate of more than 46 per cent, and if the trend continues, said San Francisco Mayor London Breed, her city will require at least 5,000 more hospital beds as well as 1,500 more ventilators.

In Los Angeles, the country’s second largest city, the situation was even more desperate.

“This will not kill most of us,” Los Angeles Mayor Eric Garcetti said, but “it will kill a lot more people than we're used to dying around us”.

California’s cases are still dwarfed by New York’s – 37,258 statewide, with more than 21,300 in New York City alone – and its 80 coronavirus-related deaths are only a fraction of New York’s 387. But it is the rate of infection that has alarm bells ringing on the West Coast.

According to Dr Mark Ghaly, California’s secretary of health and human services and its chief medical adviser: “We originally thought that it would be doubling every six to seven days. [Now] we see cases doubling every three to four days.”

There is also concern that the numbers in California, the most populous US state with roughly 40 million, are much lower than New York’s because testing – while not extensive anywhere in the country – has been more comprehensive in New York.

New York surpassed 90,000 tests on Monday, with 10,000 people tested over a single night.

According to California Governor Gavin Newsom, the state has so far tested only 66,800 people. “It’s not good enough,” he said.
Chin-Hong echoed that frustration.

“We don’t even know what’s going on in our community. We don’t have enough diagnostic testing,” he said.
“We’re operating in a black box.”

Last week, in a letter seeking federal assistance, Newsom wrote that if the infection rate continued to climb, more than half of the state’s residents could become infected within two months – a staggering 25.5 million people, with as many as 5 million requiring hospitalisation. California was among the first three states to be designated national disaster areas by the federal government, along with New York and Washington.

Health experts now say that California’s response to the virus – shutting business, encouraging social distancing and putting much of the population on “shelter in place” lockdown – should lower those numbers considerably.

But the increase in infections seen in the last 24 hours shows just how far California must go to get the virus under control.

“The worst days are still ahead,” Garcetti said on Wednesday. “We’ve taken actions earlier and swifter [than other cities], but no one is immune from this virus.”

Meanwhile, Trump said just days ago that he hoped he could lift restrictions on people and businesses as soon as Easter on April 12.

“I’m a little bit outraged,” said Chin-Hong. “I get heart palpitations when I hear those comments. As somebody who knows public health and epidemiology as well as clinical medicine it just gives me shivers in a bad way.”