California Is Underreporting Recent COVID-19 Cases Due to Technical Issue

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Medical personnel test patients for COVID-19 at a facility in Hayward in March.  (Beth LaBerge/KQED)

A technical problem has caused a lag in California's tally of coronavirus test results, casting doubt on the accuracy of recent data showing improvements in the infection rate and number of positive cases, and hindering efforts to track the spread, the state's top health official said Tuesday.

Health and Human Services Secretary Dr. Mark Ghaly said in a news briefing Tuesday that in recent days, California has not been receiving a full count of tests conducted, or positive results, through electronic lab reports due to the unresolved issue, which he did not describe in detail.

The technical problems have affected the state's electronic lab reporting system known as CalREDIE.

"There's a specific component that feeds information from labs to both the state system and the local public health system," Ghaly said. "That may actually be the place where data is getting stuck."

Ghaly said the state is working "around the clock" to fix the problem, and is now asking labs to report cases manually.

"We're not sure when we will have a definitive fix," he said.

The state's data page now carries a disclaimer saying the numbers "represent an underreporting of actual positive cases" per day.

The latest daily tally posted Tuesday showed 4,526 new confirmed positives, the lowest total in more than six weeks and a precipitous drop from the record nearly 13,000 reported two weeks ago. County health officials have posted notices on their sites advising of the lag and that a drop in cases might not paint a full picture.

"Some counties, many counties, in fact, depend on the state's information to keep their own data up to date," Ghaly said. "There is no doubt that their ability to address in a timely way specific cases, case investigation[s] and contact tracing is limited."


Wendy Hetherington, Riverside County's chief of epidemiology and program evaluation, said she believes hundreds of cases a day haven't been reported in her county. The undercount impedes the ability to find newly infected individuals and quickly contact those who have been in close contact with them so they can self-quarantine to avoid spreading the disease.

"We're delaying case investigations. We're delaying follow up," she said. "We can't tell how well we're doing until this issue is resolved."

Even with the underreporting of cases, California has recorded more total positive tests than any other state, about 520,000.

Coronavirus Coverage

On Monday, Gov. Gavin Newsom gave his most optimistic report on the state's virus efforts since a second surge of cases in early June. He noted daily cases had dropped by an average of 2,200 in the last week and the infection rate of 6.1% was significantly lower than the nearly 8% recorded last month.

Ghaly acknowledged on Tuesday that the rate Newsom highlighted was based on incomplete data and that missing data is being inputted manually. He stressed that looking at one- and two-week trends can help account for missing data from individual days.

Ghaly said hospitalization data – which doesn't run through the same troubled system – has seen signs of improvement.

"These data centers [affected by the IT issue] do not have overlap with our hospitalization and ICU numbers," Ghaly said.

"And we feel confident that [those numbers] are beginning to stabilize, as the governor mentioned yesterday ... We're now down to an 11% reduction over the past 14 days. And similarly, our ICU admissions continue to reduce. That is good news."

The latest count Tuesday showed 6,302 people were hospitalized across the state, a 12% drop from the high recorded in July. Total deaths have now topped 9,500.

Ghaly advised people who think they’ve been exposed to the coronavirus to quarantine before getting their test results back.

KQED's Peter Arcuni and The Associated Press contributed reporting to this story.