Contact tracing slows COVID-19 spread

The COVID-19 virus. Courtesy of National Institute of Health
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When it comes to stopping the spread of the coronavirus, public health experts agree that being able to figure out who might have contracted the virus plays a vital role. 

“This means that we’re going to follow up with every single person who’s tested positive for COVID-19 so that they know that they have to self-isolate,” said Dr. Barbara Ferrer, director of L.A. County’s Department of Public Health, “and we have to be able to get in touch with their close contacts, so their close contacts know that they (have to) self-quarantine.”

This contact tracing enables public health officials to suppress the spread of COVID-19, preventing surges in the health care capacity and allowing for the modification of the stay-at-home order, which is why it has received so much attention from state and local officials as California begins plans to reopen its economy.

Gov. Gavin Newsom announced recently that he has teamed up with University of California, San Francisco, and University of California, Los Angeles, to immediately begin training workers to trace the spread of the virus across the state.

With a goal of building an army of 20,000 tracers in two months, Newsom’s program hopes to contain the virus, as trained workers are then deployed to various counties across the state.

Much of this work can be done via phone, text, email and chat, while a new statewide database will help local health departments trace infected people and their contacts as they travel through the state, according to California Department of Public Health officials. 

That being said, L.A. County, along with 22 of California’s 60 other local health departments, is actively tracking exposed contacts of those who’ve tested positive for COVID-19, according to Newsom.

In fact, Ferrer says about a quarter of the L.A. County’s 4,000 public health employees have been tracking COVID-19 patients since before the “Safer at Home” order was put in place, including the positive results reported here in the Santa Clarita Valley.

“We are grateful to the governor for expanding the capacity for all the counties to have more resources to do contact tracing,” Ferrer said. “We’re the largest county. We have the most cases. We will continue to need a lot of resources, but we’re welcoming the governor’s efforts and working very closely with the state Department of Public Health, who have been extraordinarily excellent partners through all of this … And we’re doing a really great job.”

Those tracers have been divided into two teams: the larger focusing on following up on every positive COVID-19 test result, while the other focuses on investigating cases in institutional settings, such as skilled nursing homes, assisted living and correctional facilities. 

“Obviously, as our numbers grow, we need more people,” Ferrer added. “Many people are on reassignments and have been trained, including some folks who have come from other county departments that are, in fact, doing contact tracing as we speak.” 

With each positive result, tracers interview them, identifying who they’ve interacted with, and then notify those people that they need to isolate or quarantine.

Ferrer estimates tracers reach somewhere between 80%-85% of people who are positive. “When we don’t reach people, it’s (because) they either don’t take our calls at all over a three-day period or we don’t have good contact information.”

Before stay-at-home restrictions went into place, tracers had to contact an average of eight people per positive result, which has now decreased to an average of five per case since the order took effect, according to Ferrer.

“If you have 1,000 new cases a day, that’s 5,000 people that need to be contacted,” she said, later adding that she expects that number to increase back to eight as the restrictions are eased. “We are also going to track information that helps us understand how effective we are as a county together (are) slowing the spread of COVID-19, because we cannot have a surge in the number of cases and feel comfortable with continuing to loosen restrictions.”

That being said, Ferrer reminded residents that just because restrictions are being eased does not mean the virus has gone away, nor become less deadly or less infectious. 

“The virus is still out there acting in a very similar way that it was acting in March,” she said. “It’s capable of infecting a lot of people when people are in close contact with each other, and for some people, it can be quite dangerous and even deadly. And, we have to keep that information in mind.” 

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