Your Health

Stanford doctor launches survey to predict COVID-19 spread

Dr. Lawrence “Rusty” Hofmann saw the relatively sparse number of Americans tested for COVID-19 and concluded, as many have, “What we’re doing right now just isn’t working.”  

But Hofmann, a professor and chief of interventional radiology at the Stanford School of Medicine, is doing something about it. He’s led the development of a new online tool created by a team of Stanford

Dr. Lawrence Hofmann

Medicine scientists that can be used to spot at-risk COVID-19 areas across the country.

The Stanford Medicine National Daily Health Survey tracks participants for symptoms and essentially warns of potential COVID-19 cases in the making. Taken collectively, scientists can use the data to pinpoint potential outbreak clusters, thus preparing hospitals and health-care workers for potential surges. Likewise, streams of data showing benign reactions could indicate when and where shelter-in-place restrictions can be lifted. As of last week, more than 500,000 were participating in the survey since its April 2 launch.

“We want to get into the millions,” Hofmann said.

He acknowledged concerns that some populations may see limited participation – seniors with limited or no computer access, for instance. But so far, Hofmann said he’s seen “a good swath” of age distribution in the survey results. He said it was premature to offer any analysis on results so far.

How the survey can help

Coronavirus data shows an average 10-day turnaround time between infection and symptoms. Survey responses, according to Hofmann, could make up for lost time and raise the alarm sooner.

“The survey is straightforward, requiring basic, nonspecific information, and covers questions like age, gender, number of people at a residence and whether a user had any exposure to someone with the coronavirus,” said Hofmann, a 15-year Los Altos resident. “It also asks users to check from a list of symptoms that include coughing, fever, difficulty breathing and loss of taste or smell. The survey ensures anonymity of the user.”

Recruiting participants is key, Hofmann noted.

“To work, this survey needs people,” he said. “My hope is that people see taking this survey as their civic duty and as a way to be involved in fighting COVID-19.” 

It’s equally important, he indicated, for people to take the survey daily. The initial form takes approximately 2 minutes to complete, and subsequent check-ins take even less time. The data collected will be shared broadly with public health officials and health-care professionals to help inform decision-making and hospital preparedness.

“It’s a lot like our national air defense system,” Hofmann said. “It picks up incoming threats thousands of miles out so that we can prepare our defenses.”


Hofmann said the extra time provided by survey results, coupled with local testing results, could be critical for finding bed spaces, organizing hospital staff and securing equipment necessary for incoming patients. He said it will allow health officials to better respond, including by sending supplies and resources where surges will occur and developing public health policy – for example, implementing or lifting shelter-in-place orders.

Hofmann also acknowledged that the survey will inherently capture people who might have other illnesses, due to symptom overlap. But over the past decade, tracking of colds and flus has created a relatively predictable pattern of infection rate and timing for such viruses. In addition, survey data coupled with in-person swab data can be used to further refine predictions. Data that deviates from that pattern, he added, would help differentiate COVID-19 from other illnesses.

“This survey is crucial for monitoring symptomatology and understanding what’s happening on a continual basis, rather than a single point in time, like the swab test,” Hofmann said. “We don’t want to be caught flat-footed, because this fight isn’t over until we have a vaccine.”

To take the survey, visit

Those interested in partnering with Hofmann and his team can email Leslie Haas at [email protected]

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