Researchers at UCSF are conducting a study, funded in part by a pair of men who live in Bolinas, that will test nearly every resident in the rural town as well as a group of residents of the Mission District in San Francisco, to determine who might have COVID-19 currently, as well as who may have already had it and not known it.

"We don't know if there have been a lot of people infected. We don't know that and we don't know if we have much immunity. We have no idea," says Dr. Aenor Sawyer, a UCSF surgeon and Bolinas resident who specializes in health technologies. The UCSF study, at the prompting of venture capitalist Jyri Engestrom and pharmaceutical exec Cyrus Harmon, is conducting drive-thru testing for 1,680 of Bolinas' 2,000 residents who signed up.

Dr. Bryan Greenhouse, who is leading the study, says in a statement, "All our public health decisions, including when it will be possible to relax regional and statewide shelter-in-place orders, are driven by rough assumptions about how this virus behaves based on very limited data. Studying in detail how the virus has spread in these two distinctive communities will give us crucial data points that we can extrapolate to better predict how to control the virus in similar communities nationwide."

The prevalence of the virus in the small seaside community may not be known, but there have been no confirmed cases there yet. As the Marin Independent Journal reports, though, more than half the town's residents are over the age of 60 and therefore especially vulnerable to severe cases.

As this website for the project explains, the study participants will receive free tests for the coronavirus, as well as antibody tests, with testing beginning Monday morning. The idea is to take a community-wide look at how the virus is spreading in both a rural community, and in an urban one. More testing will resume in San Francisco on Saturday for residents who live in a specific range of blocks in the Mission — as Mission Local reports, they will be testing up to 5,700 residents who reside between South Van Ness and Harrison Streets, between 23rd Street and Cesar Chavez Boulevard. Testing will take place from 9 a.m. to 5 p.m. April 25 to 28 at four different sites, and residents who live within those boundaries can make appointments here.

Anyone who tests positive for the virus will get follow-up calls from UCSF and will need to self-isolate. Those who test positive for antibodies will also be informed.

The organizers have posted a GoFundMe campaign to raise $250,000 — Engestrom and Harmon provided $300,000 in initial funding for the project, but they say if they reach the fundraising goal there will be a second round of follow-up tests in Bolinas at a later date.

"You may have seen in the news that it is common for this virus to infect people but not cause symptoms, which has made it hard to stop the spread of infection," the researchers write. "By understanding how common this infection is in the community (in people with or without symptoms), we can help support public health efforts to prevent the spread of infection."

This study comes just weeks after similar antibody prevalence testing by Stanford researchers took place in Santa Clara County, the raw results of which made a big splash in the news on Friday. That study found prevalence of 1.5 percent in the community, meaning that 1.5 percent of participants had been exposed to the virus likely without knowing it or showing serious symptoms — and researchers weighted the results to conclude that between 2.5 and 4.2 percent of county residents had had the virus.

Since that data came out, other scientists have come out saying it should be taken with a grain of salt for multiple reasons. As SFGate reports, UCSF epidemiologist Dr. George Rutherford questions the conclusions of the Stanford study, acknowledging that it still needs to be peer-reviewed and the researchers felt immense pressure to rush out their results. He thinks the raw data simply confirms what is already a common belief. "In the medical community, the thought is that one percent of people have been exposed in the Bay Area, and it's a little higher in Santa Clara County," Rutherford says.

Dr. Natalie E. Dean, a biostatistics professor at the University of Florida, said similar things about the weights applied in the study, via Twitter. "Having had experience with these types of weighted surveys, I am always a little skeptical when the weighted result is very different from the unweighted result," she writes. "Weights can be wonky."

Hopefully with more tests like the Bolinas and San Francisco efforts, a clearer picture will soon emerge about the as-yet-unknown spread of the virus to date.

Other small communities are going to be seeing similar broad-based testing, all inspired by the small Italian city of Vo, where a project like this already is underway. The UCSF researchers say that Telluride, Colorado; Jackson Hole, Wyoming; and Park City, Utah are all conducting similar whole-community tests.

"The Italian town of Vo, pop. 3,300, was the first to test its entire community for COVID-19," the researchers write. "Eighty-nine people tested positive and were quarantined. The team traced their recent contacts and quarantined them too, whether or not they had symptoms. In a second round of testing 6 people tested positive and 14 days later they had eradicated coronavirus in Vo."

Related: Large-Scale Antibody Test Suggests As Many As 80,000 Santa Clara County Residents Have Already Had COVID-19

Photo courtesy of UCSF