The Stanford Health Care Clinical Virology Laboratory has launched a diagnostic test developed for the virus that causes COVID-19.

The test is being used for patients at Stanford Health Care and Stanford Children’s Health suspected of being infected with the respiratory virus SARS-CoV-2, which is spreading globally after being first identified in Wuhan, a city in China, late last year. It is expected to deliver results within 12-24 hours.

(Editor’s note: Updated information on how Stanford’s test is being used can be found here.)

As with all currently available tests, it’s not yet clear how long a person needs to be infected before testing positive, or whether someone who's infected could be identified by the test before displaying symptoms.

Public health experts have indicated that prompt identification and quarantine of infected people is critical to limiting the spread of the virus, which can be deadly to the elderly or those with other health problems. The global mortality rate of the virus, according to the World Health Organization, is estimated to be around 3.4%. Because many mild cases may remain undiagnosed, the actual mortality rate may be much lower, however.

As of this morning, more than 160 people in the United States have been diagnosed; experts expect the actual number of cases nationwide is much larger. Washington and Northern California are currently most heavily affected, but cases have been diagnosed in several states.

Clinical virologist Benjamin Pinsky, MD, PhD, associate professor of pathology and of infectious diseases at the Stanford School of Medicine, and his team in the clinical virology lab began working on the test in late January. They spent February validating and confirming that the test meets the requirements to be a useful clinical tool.

“The test successfully identified the presence of SARS-CoV-2 in positive samples without cross-reacting with the seasonal coronaviruses or other common respiratory viruses, including influenza,” Pinsky said.

Crown-like spikes

Coronaviruses are a family of viruses named for the crown-like spikes found on their surface. They carry their genetic material in single strands of RNA, rather than DNA. They infect a variety of human and animal hosts, causing mostly upper-respiratory symptoms like those of the common cold.

Until recently, two coronaviruses have been known to have caused severe disease in humans: Middle East Respiratory Syndrome, or MERS, identified in 2012, and Severe Acute Respiratory Syndrome, or SARS, which was identified in humans in 2002. The SARS-CoV-2 that causes the currently circulating COVID-19 disease is the third example.