OSU Bend neighborhood sampling suggests 1 in 1,000 infected with COVID-19

(Update: OSU explains estimate in light of no positive cases in Bend)

No one tested positive; organizers hope to do another round of sampling

BEND, Ore. (KTVZ) – Results from two days of door-to-door sampling in several Bend neighborhoods by Oregon State University and OSU-Cascades suggest that one person in 1,000 in the Bend community during the weekend of May 30-31 had the novel coronavirus that causes COVID-19, researchers announced Wednesday.

“This level of prevalence is consistent with Bend residents being careful about social distancing, wearing masks and staying home prior to Phase 1 reopening in Deschutes County,” said project leader Ben Dalziel, an assistant professor in OSU’s College of Science. “One in 1,000 is low, but the virus is still in the population and we know it is readily transmitted.” 

The study, Team-based Rapid Assessment of Community-Level Coronavirus Epidemics, known as TRACE-COVID-19 for short, began in Corvallis and expanded to Bend in collaboration with OSU-Cascades and Deschutes County Health Services.

TRACE uses a statistical model based on the number of samples, the number of positive tests and prior information on the prevalence of the virus to estimate the proportion of the community that is infected during the period when the samples were collected. 

For example, during the third week of sampling in Corvallis, there also were no positive tests among TRACE participants, but prior information on prevalence in the community nonetheless led TRACE models to estimate a prevalence of approximately one per 1,000 in the community as a whole.

In Bend, 30 two-person TRACE field teams worked in 30 neighborhoods, leading to the sampling of 615 people. A total of 342 households, or 68% of households visited agreed to participate in TRACE.

None of the community members who participated in the May 30-31 sampling tested positive for SARS-CoV-2, the virus that causes COVID-19. With 100,421 residents, Bend represents slightly more than half of Deschutes County’s population.

“While this low level of prevalence is good news, residents should continue to act with caution,” said project co-leader Jeff Bethel, an associate professor in OSU’s College of Public Health and Human Sciences and part of the TRACE leadership team.

“The larger the number of other individuals that someone comes in contact with, the greater the likelihood that at least one of them is infected," Bethel said. "These results are consistent with the emerging knowledge that there can be a low level of prevalence in the general population at the same time there are clusters of infections in higher-risk environments.”

Becky Johnson, vice president for OSU-Cascades, said the prevalence testing provides valuable in-the-moment data.

“As Bend and other communities continue to reopen, it is important that we maintain watch on the prevalence of COVID-19 in Central Oregon,” Johnson said. “I am happy that OSU-Cascades and many of our students are contributing to this ongoing public health awareness.”

The same weekend that TRACE field workers canvased Bend, public works staff collected sewage samples for a related coronavirus prevalence study being led by researchers from the OSU College of Engineering. Those data are still being analyzed.

TRACE leaders said they are hoping to schedule another round of sampling in Bend.

Dr. George Conway, director of Deschutes County Health Services, said TRACE sampling in Bend provided a valuable sense of whether COVID-19 infections are widely distributed or at a high rate in the general population.

“These results from Bend are reassuring,” Conway said. “However, COVID-19 cases and case clusters continue to occur in Bend and elsewhere in Deschutes County. We strongly recommend that residents, visitors and workers continue to be vigilant in maintaining physical distance.

"In circumstances where you cannot maintain a distance of 6 feet, wear a cloth face covering to protect others and wash your hands frequently, or use hand sanitizer where water and soap are not available. If you feel ill, please stay home and contact your primary health care provider.”

Corvallis sampling began the weekend of April 25-26 and continued the subsequent two weekends. The fourth weekend of sampling in Corvallis, originally scheduled for May 16-17, will take place Saturday and Sunday, June 13-14, to help determine if the easing of stay-at-home orders leads to a jump in the prevalence of the virus in the Corvallis community.

Prevalence in Corvallis ranged between one and two per 1,000 through the first three weeks of the project, which is consistent with residents adhering to Gov. Kate Brown’s Stay-Home-Save-Lives policy.

The TRACE study is a collaboration of five OSU colleges – Science, Agricultural Sciences, the Carlson College of Veterinary Medicine, Engineering, and Public Health and Human Sciences – in partnership with Deschutes County Health Services and the Benton County Health Department.

The study is being funded by OSU and grants from the David and Lucile Packard Foundation and PacificSource Health Plans, and has been aided by work from the OSU Foundation and the OSU Alumni Association. The diagnostic testing component of TRACE operates through a partnership between the Oregon Veterinary Diagnostic Laboratory, which is located at OSU, and Willamette Valley Toxicology.

At each home visited by TRACE field workers, members of the household are invited to participate in the study. Those who choose to take part are asked to provide information such as their name and date of birth; to fill out a simple consent form; and to answer a few confidential, health-related questions.

Participants are given a nasal-swab test kit that they administer to themselves inside their home and their minor children if they want them to take part. The field staff wait outside, and the participants leave the completed test kits outside their front door. Field staff maintain a safe distance at all times and do not enter anyone’s home. The safety of participants and TRACE field staff is a key part of the study’s research design.

The tests used in TRACE-COVID-19 collect material from the entrance of the nose and are more comfortable and less invasive than the tests that collect secretions from the throat and the back of the nose.

The field workers leave participants with information about the project and how they will receive their results – available in seven to 10 days – as well as health guidance from their county health department and the Centers for Disease Control and Prevention. Participants in the study are sent their results and those of their minor children by secure email with receipt by standard mail delivery as a backup. Everyone’s personal information is safeguarded.

For more information TRACE, visit the TRACE-COVID-19 website. The site includes a list of frequently asked questions.

COVID-19, first reported to the World Health Organization on Dec. 31, 2019, has been confirmed in more than 7 million people worldwide and has killed more than 400,000 people. In the United States, there have been nearly 2 million reported cases – including nearly 5,000 in Oregon – and more than 110,000 deaths nationwide. As of Tuesday, Deschutes County has had 134 cases and no fatalities.

Meanwhile, OSU will conduct its fourth round of door-to-door sampling in Corvallis for the novel coronavirus that causes COVID-19 on June 13-14, roughly one month after the easing of stay-at-home restrictions.

The study, Team-based Rapid Assessment of Community-Level Coronavirus Epidemics, known as TRACE-COVID-19, began the weekend of April 25-26 and continued the subsequent two weekends.

The fourth weekend of sampling had originally been scheduled for May 16-17 but was rescheduled by TRACE leaders to help determine if phase one reopening by Benton County and relaxing of stay-at-home orders led to a change in the prevalence of the virus in the Corvallis community.

“The first three weeks of OSU’s sampling for the virus in Corvallis presented a consistent pattern of low prevalence in the community,” said Ben Dalziel, an assistant professor in OSU’s College of Science and the project leader. “Over three consecutive weeks, the prevalence ranged from approximately one to two in 1,000. Those results suggest that stay-at-home policies indeed flattened the curve as intended. The number of confirmed cases reported by the Benton County Health Department portrayed a similar picture.”

Corvallis’ population is 58,641, comprising more than half of the 93,053 people who live in Benton County.

“Benton County Health Department is extremely fortunate have OSU’s energetic and inspired researchers as our partners,” said Charlie Fautin, the department’s interim co-director. “This study provides unique information about how the virus is moving through the population, which adds a new dimension to the numbers we get from hospitals and medical clinics. Few other local health departments – especially small ones like ours – have access to this sort of real-time community testing data.”

In announcing weekly prevalence results, the TRACE team follows reporting policies used by the Oregon Health Authority and local health departments by not announcing numbers of positive cases between one and nine. Doing so may contribute to identifying an actual community member who tested positive, Dalziel said.

TRACE expanded to Bend on May 30-31 with funding from PacificSource Health Plans, which will also help pay for the upcoming weekend of sampling in Corvallis. Also in Bend on May 30-31, a research project led by the OSU College of Engineering, Coronavirus Sewer Surveillance, collected sewage samples that will be analyzed for the prevalence of genetic material from the virus.

Sewer surveillance will take place in Corvallis as well the weekend of June 13-14.

While one case in 1,000 in Corvallis’ sampling may seem like a low number, it still represents a threat in the absence of a vaccine, said Jeff Bethel, an associate professor in OSU’s College of Public Health and Human Sciences and part of the TRACE leadership team.

“It is important that everyone continue to follow the advice of public health officials regarding face masks, hand washing and other sanitizing methods, and social distancing,” Bethel said. “All evidence suggests that SARS-CoV-2, the virus causing COVID-19, is highly contagious. The larger the gathering, the greater the likelihood that you will encounter an infected individual, regardless of whether they show symptoms.”

The study was initially funded by OSU and a grant from the David and Lucile Packard Foundation, and has been aided by work from the OSU Foundation and the OSU Alumni Association. The diagnostic testing component of TRACE operates through a partnership between the Oregon Veterinary Diagnostic Laboratory, which is located at OSU, and Willamette Valley Toxicology.

“The first three weeks of data provide a very useful baseline from which we can monitor in close to real time how the prevalence of the virus might have changed as Corvallis began to reopen,” Dalziel said.

At each home visited by TRACE field workers, members of the household are invited to participate in the study. Those who choose to take part are asked to provide information such as their name and date of birth; to fill out a simple consent form; and to answer a few confidential, health-related questions.

Participants are given a nasal-swab test kit that they administer to themselves inside their home and their minor children if they want them to take part. The field staff wait outside, and the participants leave the completed test kits outside their front door. Field staff maintain a safe distance at all times and do not enter anyone’s home. The safety of participants and TRACE field staff is a key part of the study’s research design, Bethel said.

The tests used in TRACE-COVID-19 collect material from the entrance of the nose and are more comfortable and less invasive than the tests that collect secretions from the throat and the back of the nose.

The field workers leave participants with information about the project and how they will receive their results – available in seven to 10 days – as well as health guidance from the Benton County Health Department and the Centers for Disease Control and Prevention. Participants in the study are sent their results and those of their minor children by secure email with receipt by standard mail delivery as a backup. Everyone’s personal information is safeguarded.

“It’s important to remember that COVID-19 is still with us, but prior TRACE-COVID-19 sampling indicated that Benton County communities were successful in limiting spread at that time,” Fautin said. “Our hope is that the information from this round of testing, and future efforts being proposed by OSU, will provide the information our communities need to continue to reduce the impacts of this ongoing pandemic.”

For more information TRACE, visit the TRACE-COVID-19 website. The site includes a list of frequently asked questions.