California, with twice the population of New York state, has conducted fewer COVID-19 tests and is still waiting for results from most of those it has tested.

This lag is crippling California’s ability to track the disease and understand how effective shelter-in-place orders have been to contain it, experts say. Meanwhile, COVID-19 cases have climbed above 4,600 in the state and more than 1,600 in the Bay Area. Deaths reached 92 in California, including 35 in the Bay Area.

Statewide, public and private labs have conducted 88,400 tests, Gov. Gavin Newsom said Friday in Los Angeles, and pointed to a problem with California testing: The results aren’t immediate.

“Tens of thousands are still waiting for results,” Newsom said at a news conference.

New York issued its shelter-in-place order later than California. It has the most cases and deaths in the country, and its numbers are rapidly climbing as hospitals become overwhelmed. But the state has conducted more tests than California: 145,753 as of Friday, according to the Atlantic’s COVID tracking project. That’s 65% more than California. Unlike California, New York had no pending test results on Friday, according to the Atlantic’s tracker.

There’s no clear answer why California, which implemented the country’s first shelter-in-place order, has lagged behind in testing. But a shortage of basic materials and other factors help to explain it.

New York got early approval of a state COVID-19 test. But even with new lab tests being approved in California, there’s still an ongoing shortage of staffing and supplies like swabs and personal protective gear to conduct them — which has been true across the country.

To speed up test production, Newsom said the state was trying to procure 3-D-printed swabs.

“You’re going to see those numbers continue to rise significantly and approvals are coming in on a real time on daily basis,” Newsom said.

The U.S.’ testing capacity, although rising exponentially every day, lags far behind South Korea, which says it tests tens of thousands of people daily. With strong testing and quarantining measures, that country has seen relatively low numbers of cases and deaths.

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In the U.S., although a COVID-19 test was available early on from the World Health Organization, the Centers for Disease Control and Prevention developed its own test. But processing at CDC’s lab in Atlanta takes days to get results, and the initial test yielded some faulty results, requiring fine tuning.

On Feb. 29, the Food and Drug Administration relaxed its rules and started issuing emergency-use authorization for other public and private tests. New York’s state public health lab was the first to get approval — on the same day.

According to the FDA’s list of authorized tests, California does not have one. The state’s Department of Public Health did not respond to questions about why the state hadn’t developed a test and whether it was working on one.

There are 22 state and county labs processing tests in addition to a growing list of private ones. Based on the FDA’s Feb. 29 guidance, Quest Diagnostics was one of the first private companies to release a test on March 9 out of its San Juan Capistrano lab, a spokeswoman said. Many more have followed with approval from the FDA.

Infectious disease experts warn that lack of testing hinders the state’s ability to track and contain the disease.

“In the grand scheme of things, the whole idea of this sheltering in place is to bring the number of new infections down, but if we don’t know where we are on the infection curve, we’re steering blind,” said Warner Greene, a senior investigator with biomedical research organization Gladstone Institutes.

“Testing is the key to know if we’re having an effect with our social distancing,” he added.

Greene said that unlike other countries that aggressively tested early on for COVID-19, the U.S. got to the point where we had to shelter-in-place to not overwhelm the health care system. But until we know how many people have the disease and isolate them, we can’t go back to normal without the risk of continuing to spread it, he explained.

“It’s frustrating. We are facing the pandemic, an acute, lethal virus, to which we have no antivirals and no vaccines ... and it’s like we’re trying to fight this virus with one hand tied behind our backs,” he said.

Robert Siegel, a Stanford infectious disease expert, said tests are useful for treatment — to confirm diagnoses and what kind of basic precautions to take — and for public health to isolate infected individuals and not spread the virus further.

With limited tests, the CDC has issued guidance that only the most vulnerable people in at-risk populations with symptoms or who are already hospitalized should be tested. Bay Area residents who believe they have COVID-19 symptoms have been frustrated by red tape as they struggle to access testing.

Alameda resident Jennifer Dhillon, who has mild asthma, began to cough, feel fatigued, and short of breath on March 12, though she had no fever. She called her doctor at Kaiser Oakland who said it sounds like she had symptoms for the coronavirus. She said the doctor apologized that she wasn’t in a high-risk category that qualified to get a test, but told her to let them know if she felt worse.

A spokeswoman for the hospital system said it was following CDC guidelines for testing criteria.

Not knowing if she had the virus, Dhillon took precautions like wearing a mask and gloves and wiping down surfaces when she went out to protect other people. As a single mom, she wanted to know whether she was positive so she could protect her school-age son, who hasn’t gotten sick yet.

“From a public health perspective, it’s good to know how many people are showing up,” Dhillon said.

Now that she’s feeling better, she doesn’t care as much about getting a test. What she wants is an antibodies test, a developing possibility to reveal whether someone who had the virus could be immune.

“We’re going to need that, if we’re going to talk about getting the economy going,” she said.

Mallory Moench is a San Francisco Chronicle staff writer. Email: mallory.moench@sfchronicle.com Twitter: @mallorymoench