The coronavirus may have been in California before China announced outbreak, study suggests – SFGate

The novel coronavirus may have been circulating in Southern California as early as December, suggests a new study from UCLA published in the peer-reviewed Journal of Medical Internet Research.

After analyzing electronic health records from UCLA Health hospitals and clinics, researchers found that beginning the week of December 22, hospitals began to report an abnormally high number of patients experiencing coughs and acute respiratory failure compared to previous years. For reference, the Chinese government first informed the World Health Organization of the novel illness on December 31.


“For many diseases, data from the outpatient setting can provide an early warning to emergency departments and hospital intensive care units of what is to come,” said Dr. Joann Elmore, the study’s lead author. “The majority of COVID-19 studies evaluate hospitalization data, but we also looked at the larger outpatient clinic setting, where most patients turn first for medical care when illness and symptoms arise.”



The researchers compared health system and patient visit records from the period between December 1, 2019 and February 29, 2020 to previous years and found that outpatient clinic visits for those seeking care for coughs increased by over 50%. The number of visits by patients reporting coughs exceeded the average number of similar visits over the prior five years by more than 1,000.


COVID-19 diagnostic testing was scarce during the winter months, which limits the study’s findings.

“We may never truly know if these excess patients represented early and undetected COVID-19 cases in our area,” Elmore said. “But the lessons learned from this pandemic, paired with health care analytics that enable real-time surveillance of disease and symptoms, can potentially help us identify and track emerging outbreaks and future epidemics.”


A timeline compiled by Axios shows that China had evidence that something was afoot in the weeks before officially reporting the virus to the WHO.

Eric Ting is an SFGATE reporter. Email: eric.ting@sfgate.com | Twitter:@_ericting

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