Sonoma County public health investigators use critical ‘contact tracing' to detect spread of coronavirus

A team of Sonoma County public health nurses wear face masks, face shields, blue gowns, gloves and shoe covers, waiting for a caravan of cars, SUVs and pickups to start driving into a narrow downtown Santa Rosa parking lot.

One afternoon last week, the people who arrived in the vehicles, often families and couples, appeared a little bewildered. Many, however, are thankful to get a break from home quarantine, eager to speak to someone in person, someone who understands what they're enduring.

This is not just any Monday through Friday drive-thru county testing site to detect the new coronavirus. The people in these vehicles are unique. They are our friends, neighbors and co-workers, but there's a great probability they have COVID-19 because of their close contacts with others infected. Public health officials say identifying, testing and monitoring these high-risk individuals are crucial steps to control the spread of the infectious disease around the county.

This is the essence of contact tracing, arguably the most important tool deployed by the county's team of more than 60 public health nurses, investigators, epidemiologists and volunteer doctors and nurses doing the detective work to stop or at least slow the virus outbreak.

It involves long hours of sleuthing as the team painstakingly tracks a complex web of viral transmission, from co-worker to co-worker, wife to husband, parent to child. It requires medical professionals to be nimble, chase leads and quickly gain people's trust - as the health and economic well-being of the county hangs in the balance.

“I don't know how we'd be able to accomplish the really difficult, rigorous task of contact tracing without all these people,” said Dr. Sundari Mase, the county's public health officer who is leading the critical testing regimen and the entire local offensive to protect the county from the invisible viral enemy.

Already quarantined at home, the people who pulled up in their cars one afternoon last week to be tested seemed to appreciate the parking lot interaction with the county's public health investigators and nurses.

“It's not just let me grab a specimen. It's how are you doing? People actually like the connection,” said Julianne Ballard, one of the lead public health nurses on the front lines of the local fight against the highly contagious virus.

Ballard said halting community transmission of COVID-19 involves much more than simply ordering self-isolation or collecting a test specimen from a person with a greater chance of contracting it.

“Sometimes there's difficulty getting food to the home, and sometimes people are frightened about what may happen next,” she said. “We're here to help support people in this very challenging situation.”

Suppressing outbreak

County health officials say the stay-at-home order in place since March 18, related social distancing measures and other restrictions related to the coronoavirus pandemic have helped avoid doomsday scenarios predicted by early computer modeling of area cases.

That modeling for Sonoma County provided by Imperial College London suggested up to 1,500 ?residents at one time would be hospitalized when virus infections peaked in early June. Another batch of modeling projections, which take into account dramatic effects the unprecedented local public health emergency directive that closed most businesses and schools, parks and beaches has had suppressing COVID-19, is expected this week.

According to the earlier modeling, some 900 coronavirus patients should be in the hospital around this time.

As of Friday, there were only 23 confirmed or suspected COVID-19 patients in local hospitals and three who needed intensive care, according to hospital data provided by the state.

Every local resident who tests positive for the virus triggers a new line of investigation for the contact tracers to find potentially more infected people.

The county's expanded testing, which started Saturday with a group of local health care workers, likely will reveal many more virus cases in the area and more threads to follow.

“Every day we come back to work and we wonder what the case count is going to be today. ... How hard we're going to have to work to keep that down by contacting more people and more people and more people, and it can be exhausting,” Ballard said.

During a wildfire, firefighters race to the fire lines to stop advancing flames. Their tools are fire hoses, bulldozers, axes and shovels that can be complemented by an aerial onslaught.

Against the COVID-19 outbreak, a slower-moving, mostly invisible threat, the comparable boots on the ground are public health nurses, armed with lists of names and addresses of contacts of others potentially infected. It's work that's no less urgent or vital than that of a police detective or firefighter.

Contact tracing

The county began drive-thru testing for its contact tracing program nearly three weeks ago, Ballard said. The testing is conducted by appointment only and involves only those who have been in close contact with people who have tested positive for the coronavirus.

Contact tracing has been a highly effective way of finding new COVID-19 cases, Ballard said. As of Wednesday, roughly 30% of all the people who have been tested at a contact tracing drive-thru came back positive, she said. By comparison, she said less than 0.5% of all the people county public health officials have tested who live in group settings like nursing homes, the county jail, homeless shelters, among others, have been positive.

While contact tracing has been snagging cases, local public health officials say they are finding very few cases - 36 overall as of Saturday - in which people contracted the virus from an unknown source, known as community spread. Although just 17% of total local cases, that's the most worrisome group of residents stricken because public health officials don't know how they were exposed to the virus.

“It's a good sign that we're finding our cases amongst our contacts,” Mase said.

For example, on Thursday, the county reported 22 new confirmed cases of COVID-19, the largest daily increase since the county confirmed its first local case March 2. Health officials said Friday 20 of those cases surfaced through the county's contact tracing work.

Cases identified through contact tracing have been “targeted,” because those people were at high risk of having the virus, the county's health officer said Friday during her daily press briefing.

“We're testing them proactively before even some of them are getting sick. In fact, we've had many asymptomatic contacts who also (test positive),” she said, adding that infected residents classified as community transmission cases are harder to address.

“If we had somebody in the community who developed COVID and we had no idea where it came from, that's when we're wondering, OK, it's out in the community and it's out of control. We're not in control of it,” Mase said. “So that's why it's really good we're not seeing those cases as much at this point.”

As of Saturday, the county has reported 219 confirmed local cases of the virus. Besides the 36 people (17%) who were deemed infected through community transmission, 102 people (47%) have been classified as “close contact” cases, 42 (19%) related to travel and 38 cases (18%) remain under investigation, according to county health department figures.

Bigger control team

To combat the coronavirus pandemic, the county's public health division had to recruit more staff to bolster its 11-member disease control unit, which normally includes seven public health nurses, two public health investigators, one epidemiologist and a senior office assistant.

Nine additional public health nurses were cross-trained and assigned to the disease control team, while three public health nurses were brought in to do active case identification by going out in the field among vulnerable groups of people to find cases of COVID-19. The team also has another three public health nurses working with homeless people.

Ballard, who normally works as a supervisor for public health's high-risk pregnancy field nursing team, is among the department's nurses on loan to the disease control team.

Mary Miller, nursing services director for public health, said a host of volunteers that include local physicians, nurses and members of the Medical Reserve Corps brings to 61 the number of people working on contact tracing for the coronavirus.

Miller, who previously supervised the disease control team for 20 years, said she's seen a lot of emergent diseases.

“If you think about all of the emerging diseases just since I've been here, West Nile Virus, Zika, H1N1 (swine flu) - all of those have a component of what we are doing now,” said Miller, adding that public health staff also have honed their skills chasing outbreaks of tuberculosis, syphilis and other sexually transmitted diseases.

“We're doing the same work and we're committed to doing that work,” Miller said of the team's detective work to track the local outbreak of COVID-19.

Daily case analysis

The county's shelter-in-place directive and related public health restrictions have greatly limited movement of the virus, local health officials said.

Lucinda Gardner, an epidemiologist with the disease control team, said after the order went into effect March 18 most people who contracted the virus through a close contact got it at home or at work. The majority of the county's confirmed virus cases are centered in the county's denser central communities of Santa Rosa and Rohnert Park/Cotati.

Gardner's day usually starts with a 7 a.m. phone call to update the team. By 8 a.m., she's at the county public health offices on Fifth Street in downtown Santa Rosa, checking on virus cases and starting to enter and manage data. After various meetings throughout the day, Gardner and Jenny Mercado, the other epidemiologist on the team, pull all of the day's coronavirus statistics together and update the county's COVID-19 website, which includes newly confirmed cases, the number of people recovered and a host of other demographic information.

Mercado, who has worked in infectious disease control her entire career, has been with the county public health division since 2002. The area of infectious disease consistently changes and there's a great deal of variety in the field, she said.

Gardner said she didn't expect the pandemic to be a coronavirus. “I thought it would be influenza,” she said. “Influenza is always changing from year to year, so I think it always has a great potential for a pandemic.”

As epidemiologists, Gardner and Mercado summarize the case data, count the number of contacts for each case, look at worksites and addresses and social networks to try to figure out how COVID-19 is moving through the community. It's a tedious task that arms the public health nurses and volunteer phone workers with the information they need to identify each piece of what amounts to a large and complex puzzle.

Gardner said the work they do would not be possible without the collaboration of “contacts” in the community who are willing to share information.

“It takes so much information to understand what's happening and synthesize what's going on and allow us to do the work that we do, to share the summarized data with leadership and with the public, so everyone understands how this (coronavirus) is moving through our community,” Gardner said.

Enhanced testing

Saturday's start of expanded testing is going to create more work for the disease control team as additional positive cases are identified. Mase said last week she hopes to increase testing to between 600 and 800 tests daily countywide over the next few weeks. Currently, there are between 150 to 200 tests a day conducted by the county public health lab, commercial laboratories, community clinics and hospitals.

Sonoma County Supervisor Shirlee Zane, a strong supporter of county health services, said public health nurses are our first responders in the local fight against the COVID-19 pandemic. She said we're going to need more of them.

“If I had my magic wand, I'd hire twice as many of them,” Zane said. “If you triple the amount of testing, you're then going to triple the amount of cases that you need to trace.”

Zane said expanded testing is likely to find many more people who have the virus, but are showing no symptoms and can unknowingly spread the virus. Reaching out to them will require more public health nurses, she said.

Prior to the arrival of COVID-19 last month, the public health division had been losing staff and there was even discussion about getting rid of the public health lab on Chanate Road and creating a regional lab with other counties.

That would have been a mistake, Zane said.

Ballard, one of the county's lead public health nurses, said each connection made through contact tracing of the elusive coronavirus ultimately affects the entire community. For a public health nurse, the patient is the whole community, but the ability to connect with people and build relationships are no less important than they are for a nurse working in a hospital.

“In public health, the patient is all of you,” she said.

You can reach Staff Writer Martin Espinoza at 707-521-5213 or martin.espinoza@pressdemocrat.com. On Twitter @pressreno.

Editor's Note: This story has been revised to reflect that it was epidemiologist Lucinda Gardner who said she at first expected the pandemic to be influenza. She and epidemiologist Jenny Mercado were interviewed on the same conference call.