Inside San Francisco’s Ambitious Plan to Bring Universal Coronavirus Testing to An Entire U.S. City

Public health experts can’t say it enough: If the U.S. is going to beat COVID-19, the country needs to ramp up testing. But there’s no single blueprint for cities and states to follow as they respond to that call.

Some, like Los Angeles, are going big. In late April, L.A. became the first major city to offer free testing to any resident. Others, like San Francisco, are doing things in a more progressive style, with goals that are just as ambitious.

The latter is strategizing from a place of strength. Thanks to some of the nation’s earliest stay-at-home orders, San Francisco has, so far, flattened the curve with relative success. Businesses around the city have been allowed to reopen for curbside pickup. And key to continuing on the path back to normality is continually testing residents, city officials say, with a focus on “vulnerability” above all else.

Over the past 11 weeks, since San Francisco began analyzing tests at city labs rather than shipping them off to Atlanta, officials have been gradually widening the circle of who is eligible to get one. The decision not to let just anyone sign up was partly about limited resources. It took time for the city to stabilize its supply chain. But public health officials also wanted to prioritize those who were most at risk.

At first, data about risk factors were limited, with officials focused on simple criteria like whether someone had traveled to China. Since then, the calculation has gotten more complex. Research and reports suggest that the virus may be exploiting systemic inequalities, and the deep blue city has, unsurprisingly, taken that to heart. Shortness of breath is one indicator of who might need to be tested for COVID-19. According to San Francisco’s public health department, income is too.

The need to take people’s circumstances into account is a lesson the city learned in the 1980s, from fighting another then-mysterious virus, HIV. “Who is more likely to be in settings where they’re not able to adequately protect themselves?” says Dr. Susan Philip, the city’s director of disease prevention and control. Answering that question is important from an equity standpoint, she says, “but it’s also very important from the standpoint of protecting the entire city.”

The strategy has challenges, like identifying all those who are vulnerable and, on top of that, figuring out how to convince them that getting tested is in their best interest.

San Francisco has machines that are capable of analyzing 4,300 tests a day, according to the health department. Currently, they’re analyzing about 1,300, and health officials have set a goal of raising that to between 1,600 and 2,000 in the coming weeks. Among the reasons for that gap are a continuing struggle to get supplies needed to conduct tests, as well as the need to train staff and obtain protective equipment. But officials also don’t want to turn anyone away.

In the days following L.A.’s announcement, there were reports that a website for sign-ups crashed and that appointments filled up before some people were able to get them. “What we knew here,” says Philip, “is we wanted to make sure that as we expanded, we didn’t have to contract.”

In the beginning, that meant focusing on only the most obvious group: those who feel sick. Initially testing was limited to those who felt ill and who had also traveled to Wuhan, then the Hubei province, then China. By late April, the city had expanded testing to anyone experiencing symptoms—including both the nearly 900,000 residents of S.F. and those who commute in from other places for work.

As the city’s capacity for testing continued to increase, officials faced a more complicated exercise in prioritization. Research has made it increasingly apparent that it’s also important to test people who feel well. Some studies suggest that half of those who are positive for COVID-19—and therefore capable of spreading the virus—may be asymptomatic. Knowing resources are still limited and a negative test result is generally not as useful as a positive one, which asymptomatic people do you seek out?

One interpretation of “vulnerability” to the coronavirus is that someone is at high risk of dying if they get it. That’s the factor the city relied on when it made the decision, announced on May 1, that testing for residents and workers at skilled nursing facilities would not only be universally available but universally mandatory. On May 19, Dr. Grant Colfax, the city’s health director, announced that about 40% of all S.F. nursing home residents and workers had been tested so far and proudly relayed that the small number of positive test results from one large nursing facility—four out of more than 2,000—had led to swift contact-tracing and isolation, potentially protecting many at-risk seniors and care workers.

Another way to interpret vulnerability is to focus on exposure: who is most likely to get infected or to transmit the virus to others? Is it the venture capitalist who has been able to work from home or the bus driver who encounters dozens of strangers every day? “Just thinking it through,” Philip says, “it’s going to be a grocery clerk or a delivery driver.” This led the city’s latest step: expanding testing to all essential workers, regardless of whether they have symptoms, on May 4. (It was also the reasoning behind offering testing to asymptomatic close contacts of people who test positive, which began in late April.)

What has the city learned? Of the 50,533 test results that have been reported to the city as of May 22, 6% have been positive. Lower-income neighborhoods, men and Latino residents have been harder hit.

The city is not going to expand testing by offering it to any particular race or ethnicity, says Veronica Vien, a public information officer for the department of public health. But the city is setting up testing sites, including a mobile one, in neighborhoods where communities of color are larger, where higher proportions of residents live in poverty, and where people might face more challenges in traveling to healthcare centers.

Another vulnerability that’s come into focus is living in crowded settings, and so the city is gearing up to expand universal testing to facilities like homeless shelters. Individuals experiencing homelessness also tend to be older and have underlying health conditions, making them vulnerable in myriad ways.

But even as the city looks to the next expansion, it’s still trying to figure out how to penetrate more deeply into the at-risk groups it’s already identified. Philip can’t say exactly how many people are eligible under existing criteria or what portion of them have been tested. But it’s not as many as public health officials would like. “We can’t look at that as a flaw with the population,” she says. “We have to look at it and say: What is it we can do better?”

A study done in late April in the Mission District, a historically Latinx neighborhood that struggles with income inequality, offered some clues.

In partnership with the city, local activists and other groups, researchers from the University of California San Francisco attempted to test everyone who lives or works in a single census tract, in the Mission. Overall, about 2% tested positive.

An overwhelming number of that group, 95%, were Hispanic or Latinx—compared to just 44% of all of those tested. About 90% of those who tested positive reported that they were unable to work from home, and infection rates were higher among those who traveled to the area for their jobs—about 6%—findings that affirmed the city’s decision to expand testing to all essential workers. (UCSF also worked on a companion study in the relatively isolated and predominantly white town of Bolinas, which found zero infections after testing nearly every resident.)

However, researchers reached only about half of the population they were trying to test. Dr. Gabriel Chamie, an investigator from UCSF, says that while they don’t have data to explain why some people did not participate—despite door-to-door appeals—they anticipated several reasons.

One is that for weeks now residents have been told to stay home, which might reasonably cause people to be afraid of coming out for testing. The neighborhood, like others in San Francisco, is also home to undocumented individuals who might fear having their data collected. Some might worry about economic consequences. “If you test positive,” Chamie says, “that might mean there’s a stretch of time where you need to self-isolate.” And if you’re the sole breadwinner for a household, that may not feel like an option. Then there’s the issue of “being labeled as positive and what that might mean,” an issue Chamie knows well from his background in HIV research.

A central lesson San Francisco is applying from its efforts to respond to the HIV epidemic, he says, is that there’s “a human side to what it means to develop an infection. It doesn’t happen in a vacuum.”

And so the city has been trying to respond on a human level, spreading the message that it’s safe for undocumented people to get tested (San Francisco is a sanctuary city) and working to provide meals and replacement income for those who couldn’t otherwise shelter in-place for two weeks. Low-income individuals who test positive and are worried about infecting their families—in the Mission study, nearly 90% of those who tested positive lived with three or more people—can be put up in a hotel room for free.

In various efforts, government officials are partnering with community organizers who are known and trusted in places they’re trying to reach. That, to Philip, is the key takeaway from decades of experience with HIV. “Community understands how best to gain information that will be helpful in our public health efforts, how to engage people in the research that will be needed to find new breakthroughs,” she says.

Outreach teams are papering neighborhoods like the Mission with more than 80,000 flyers, in several languages, that highlight testing opportunities. Teams of Chinese speakers are meanwhile going door-to-door to spread the word among business owners in Chinatown, one of S.F.’s poorest, densest neighborhoods.

Public health officials also know that combating shame associated with an infectious disease will help increase the number of people who know their status. To this end, Mayor London Breed announced that she would be going to get tested in the Bayview-Hunters Point neighborhood, an area that has experienced high rates of infection and where the vast majority of residents are people of color. “We also want to make sure we detach the stigma associated with getting tested,” she said at a virtual press conference on May 18.

There are more results to come from the Mission study. Researchers not only tested approximately 57% of people in the census tract for active infections but also for the presence of antibodies, which will suggest the cumulative number of cases that have occurred in the area over time and help reveal the footprint of the virus in the city. Results are expected at the end of May.

Philip says that while she eagerly anticipates those findings, the public health department is squarely focused on testing for active infections at this point. The reliability of antibody tests is still uncertain, and, even if that weren’t an issue, it’s not known whether people become immune after being infected with the coronavirus and, if so, for how long. “There are a lot of open science and public health questions,” she says.

Mayor Breed has said that ongoing testing will be critical to reopening, and the city has stated a goal of providing universal access to testing. But Philip says there’s no set timeline for when the city hopes to have expanded the circle completely.

In general, her department is less focused on when every San Franciscan will be able to be tested than on questions like how often high-risk individuals should be. “The reason we test is to have results we can act on,” Philip says. That’s where the public health follow-up happens: the investigation, the contact tracing, the isolation, the quarantine. But resources aren’t limitless.

Testing for vulnerable people needs to be routine—someone could get sick in between the time when they got swabbed and got their test results, she says—but it’s not yet clear just how frequent it should be. Because the incubation period of the virus is 14 days, the city is currently using general guidance that groups like essential workers should get tested no more than every two weeks, but is the optimal window every 15 days? Every month? That’s TBD.

As the city works to find more answers, and get more results, they’ll be guided by a broader mantra at the public health department. “We all have to be healthy together,” Philip says, “or we’ll all be unhealthy together.”