California Grapples With COVID-19 Data Error, Resulting In Undercounts, But Official Says Cases Still On Decline

Updated 3:29 p.m.

Two simultaneous issues with the state of California’s disease reporting system have led to a backlog of test results and an undercount of COVID-19 cases in recent data.

In a news conference Friday, California Health and Human Services Secretary Dr. Mark Ghaly said that these troubles have led to a backlog of 250,000-300,000 test results.

“Our data system failed, and that failure led to inaccurate case numbers and case positivity rates,” Ghaly said. “It also prevented counties from having some of the data they need to monitor and respond to the virus in their communities.”

Ghaly said he became aware of the “magnitude” of the issue Monday afternoon, following a press conference where Gov. Gavin Newsom shared an “early good sign” that the state’s positivity rate was declining. 

But despite a gaping hole of missing data, Ghaly said he believes “the trends we discussed earlier this week remain the same” and that California’s COVID-19 cases are trending down. 

One of the issues began with a server outage on July 25, which created a delay in lab records coming into the state’s reporting system. To resolve this, the state instituted technical changes to allow records to enter the system more quickly.

These changes were meant to be temporary, but they were not disabled, which caused more delays in lab data reporting and created a backlog of test results.

A simultaneous issue with reporting of lab results from Quest Diagnostics, a large provider of COVID-19 testing in the state, caused another backlog in the data. 

“We discovered that we were not receiving data from one of our largest commercial labs for a period of five days between July 31 and August 4,” Ghaly said. “This was due to a certificate [with a lab reporting intermediary, which forwards data from a lab to the state] that the state neglected to renew timely, which resulted in data not being able to transmit to the state.”

The issue has affected all test results coming from labs, not just COVID-19 tests, Ghaly said. 

“We won’t yet know until 24-48 hours from now — once that entire load is worked through — how many are COVID-related and how many of those are positive versus negative tests,” he said.

Data flowing into the state’s system has begun to normalize in the past 24 hours, and Ghaly said that he expects the backlog will be eliminated over the weekend. But, once the backlog is resolved, counties will still need to process and verify the test results.

Riverside County reported that the California Department of Public Health notified agencies of the delay on Friday, August 1.

Ghaly also discussed the issue in his news conference Tuesday when asked about it by a reporter. 

Counties across the state, as well as the California Department of Public Health, also added disclaimers to their COVID-19 data dashboards Tuesday, stating that the issue may have caused an undercount of cases. Sacramento County has disabled the part of its COVID-19 dashboard that contained data on laboratory results until the issue is resolved.

The state had already frozen its watch list for counties with high transmission of COVID-19 on July 31 as it transitioned from using state data on hospitalizations to federal, according to Ghaly. That list will not be unfrozen until this backlog is processed.

EdSource also reported that the data issues, and their impact on the state’s watch list, have impeded the ability of schools to apply for waivers for in-person instruction in the fall.

At the root of the issue that began July 25 is California’s CalREDIE disease reporting system, which Ghaly said “has been challenged by the volume of COVID-19 data.” He noted that short delays in the data are not uncommon.

Because of the current issues, the state is accelerating development of a new lab reporting system for COVID-19, as CalREDIE was not built for the volume of data that the pandemic has brought on, according to Ghaly.

Newsom has called for a full investigation into what happened, and those responsible for the issues will be held accountable, Ghaly said.