The coronavirus testing backlog in California remains at a staggering 59,500 — far more than other states publicly reporting numbers for pending test results — but Gov. Gavin Newsom on Thursday promised a “best in class” solution will be announced soon by a newly formed state testing task force.

California has struggled with test shortages that have prevented many people from getting tested at all, as well as slow processing times that have forced many doctors and patients to wait up to 10 days for results. The state ranks 39th out of 50 states and the District of Columbia in per capita testing, according to a Vox analysis of state testing data collected by the Covid Tracking Project.

About 92,500 tests had been conducted in California as of Wednesday, according to the state Department of Public Health. Roughly 33,000 results have been received and 59,500 are pending — 64%. Although only four other states report their backlogs — Florida, New Hampshire, Hawaii and Nebraska — the next worst on the list, Florida, has only 1,280 pending results, or 1.6% of tests conducted.

Delayed test results hamper doctors’ ability to make quick decisions about whether to isolate sick patients, and hinder public health officials’ ability to fully understand the extent of spread in real time.

The introduction this week of rapid-response coronavirus tests, including as a 45-minute test made by the Sunnyvale company Cepheid and a five-minute test by Abbott, may help ease the testing backlog. But Newsom said these tests won’t be widely available enough to make an immediate dent in the state’s testing backlog. California received only about 100 of the five-minute Abbott tests — a quantity the governor described as “insignificant.”

Part of the backlog appears to be tied to one major commercial lab, Quest Diagnostics, which is struggling to process an influx of tests quickly. The company said Wednesday it has 12 labs with 115,000 tests pending — including tests from around the country. Quest declined to say how many of those are California tests. And the state Department of Public Health declined to say how many of California’s 59,500 pending tests are held up at Quest.

The inability to do widespread testing is partly because of a worldwide shortage in supplies needed to collect samples and process the tests, including chemical reagents, swabs, extraction kits and protective gear for doctors who are collecting samples from sick patients.

But it remains unclear why California is near the bottom in overall testing, when compared with other states.

Without quick, widespread testing — and a far smaller backlog — health officials are unlikely to lift the state’s shelter-in-place restrictions.

Reopening workplaces and other institutions means cases are likely to tick up again, and health officials will need rapid testing to identify infected individuals and trace their contacts to avoid a second spread of the virus.

“We need to monitor trends so we know the next time (cases are) going up (and if) we need to shut things down again,” said Dr. Cyrus Shahpar, an epidemiologist who previously oversaw the global rapid response team at the federal Centers for Disease Control and Prevention. “The strategy will be containment. That requires massive testing, like South Korea. So we can’t release things until we have those things in place.”

Newsom said his upcoming announcement will address both diagnostic and serology tests. The latter detects the presence of antibodies in blood, which indicate whether a person has ever been infected with the virus.

“We have a new task force on tests and will provide some good news about our capacity to substantially increase our tests in the state of California,” Newsom said. “We have a remarkable collection of individuals now advising us to get to the next level, which could be best in class from an international perspective, not just a national perspective in terms of improving the time to diagnostics and ability to get more samples.”

Catherine Ho is a San Francisco Chronicle staff writer. Email: cho@sfchronicle.com Twitter: @Cat_Ho