San Francisco is building an army of people and training them in a simple strategy to help contain the spread of the novel coronavirus.

Several dozen volunteer medical students, retired nurses and city employees gathered at UCSF over the weekend to learn how to do what is known as "contact tracing." The technique involves tracking residents with the virus and identifying those who could have been exposed, and then interviewing and monitoring those people in confidential conversations.

The program is a joint effort between UCSF and the city and county of San Francisco, and will be increasing SF's contact-tracing team from about 10 to more than 100 individuals. The city has been tracking cases since the virus was first identified in a resident in early March, but this program is "more aggressive and more robust," said Dr. George Rutherford, an epidemiologist at UCSF who is helping lead the program.

"We just augmented the workforce by tenfold," Rutherford added. "We started doing it last week. We’re continuing to do it this week. We’re finishing the training for about 63 more people and will be adding more."

Rutherford said over the weekend that many UCSF medical students whose research projects in Africa are on hold and City Attorney staff were a part of the training. San Francisco's Department of Public Health said librarians will also be eligible for training.

The effort is also teaming up with DIMAGI, a software company that has been working with the Centers for Disease Control and Prevention, to introduce new technology to the contact-tracing system. People who have been exposed to the virus can sign up for daily text messages or phone calls checking in on their health and symptoms throughout the 14-day monitoring period. They can self-report symptoms via text, immediately alerting public health officials that follow up or testing may be required, according to SFDPH.

“Today, we are laser focused on the health emergency in our city,” said Dr. Grant Colfax, S.F.'s public health director. “We are doing everything we can to reduce the spread of the virus in our community, protect vulnerable populations, health care workers and first responders. But even as we respond to outbreaks now, we are looking ahead. We need to build a fast-moving, comprehensive system to track cases and support people to prevent further spread as much as possible as we ultimately move out of shelter in place into a new phase of fighting the pandemic.”

The program is among the first of its kind in the county, and the idea is to roll it out in other counties throughout the state. Massachusetts is working on a similar effort.

"Everyone else is talking about it," said Rutherford. "We’re doing it."

Rutherford said officials with the San Francisco Department of Public Health will do the initial interviews with infected patients, and volunteers will follow up with the contacts. "Each case has about five contacts," said Rutherford. "Someone who is really good at this, might be able to clear two an hour."

SF's Department of Public Health said in a statement that for the program to work, people who are contacted will need to have confidence that their participation is confidential, voluntary, based in science, and in their best interests. "There have been instances in San Francisco when people have been unwilling to work with contact investigators, either because they do not trust them, do not understand the purpose, or do not have all the information they need to feel comfortable," SFDPH said.

Experts believe that the virus spreads mainly through respiratory droplets spread among people who are in close contact with one another (within about 6 feet, though some studies suggest the distance is even farther). These droplets can be emitted from an infected person's mouth through coughing, sneezing or talking and land in the mouths and noses of people who are nearby or possibly be inhaled into the lungs. Some studies suggest COVID-19 may be spread by people who are not showing symptoms.

On Tuesday, California Gov. Gavin Newsom announced a plan to loosen the stay-at-home order that began March 19 and introduce new guidelines, such as a requirement to wear face coverings in public, that allow people to leave their homes more freely and businesses to reopen. Newsom said a ramped-up testing and contact-tracing program will be a key tool in preventing a surge in COVID-19 cases amid the new framework that doesn't yet have a start date.

Dr. Larry Brilliant, a Marin resident and epidemiologist who was part of the World Health Organization team that helped eradicate small pox in the 1970s, has been a proponent of contact-tracing in the Bay Area. As a guest on KQED Radio's "Forum" earlier this month, Brilliant made the point that California kept its case count under control with early social distancing and has numbers (25,500 cases as of Tuesday) that could be tracked more closely compared to a place such as New York, where cases have surged past 203,000.

"I think we ought to go and visit everyone of those cases in a hazmat suit," Brilliant said on Forum. "We ought to identify all the contacts. We ought to find all the contacts and then quarantine all of them."

Brilliant went on: "If we continue to do only mitigation, you run that risk of coming to that 'flattening of the curve,' and then we’re going to have to do the mitigation for months. I don’t think we should give up on containment. My experience in the small-pox program, which is a very different virus and we had a vaccine and all that, the moment we let up, for a moment, the virus came back."

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Amy Graff is a digital editor with SFGATE. Email her: agraff@sfgate.com.