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TRACE field staff door-to-door sampling in Corvallis neighborhood.

Corvallis TRACE-COVID-19 sampling June 5 and 6 to include saliva testing for antibodies

By Steve Lundeberg

Oregon State University will conduct its seventh round of TRACE-COVID-19 door-to-door sampling throughout Corvallis the weekend of June 5 and 6 for the coronavirus that causes COVID-19.

The sampling will follow the same format as the previous six Corvallis testing events with one change: In addition to a nasal swab sample used to determine if someone is currently infected, for the first time, TRACE Community participants will be invited to provide a saliva sample to be tested for COVID-19 antibodies.

“The saliva testing will show the presence of antibodies and also whether they resulted from a vaccine or from a previous SARS-CoV-2 infection,” said TRACE project leader Ben Dalziel, an assistant professor in the Department of Integrative Biology in the OSU College of Science.

“By testing for the presence of the two different types of antibodies, we’ll be able to estimate the fraction of Corvallis that has been previously infected,” said Roy Haggerty, dean of the OSU College of Science and part of the TRACE leadership team. “That fraction has not been reliably estimated to date, in large part because many infections – possibly the majority – have occurred in people with no or few signs of illness, which greatly decreased the likelihood of them getting tested, especially early in the pandemic.”

While researchers have demonstrated the sensitivity and specificity of the saliva assay, it does not yet have the clinical authorization necessary to share individual test results back to participants. However, reporting community-level seroprevalences will be useful to public health officials.

“The goal of the antibody survey is to reveal the landscape of immunity in Corvallis, which reflects our community’s history with the pandemic and can inform us about our current levels of protection,” said Dalziel. “TRACE will provide aggregate results from the antibody testing, and test results from the nasal swab samples will be returned to the participants as always.”

The last time TRACE Community field workers collected nasal swab samples in Corvallis, March 13 and 14, the results yielded a community prevalence estimate of 13 COVID-19 cases per 1,000 people, the project’s highest estimate for Corvallis by a margin of about 10 cases per 1,000.

“Even with more and more people being vaccinated, each of us should continue being careful when it comes to preventing transmission of the virus,” said project co-leader Jeff Bethel, an associate professor in OSU’s College of Public Health and Human Sciences. “And it’s important to continue monitoring community prevalence of the virus.”

All nasal swab samples containing the virus, as well as city wastewater samples collected under the direction of Tyler Radniecki and Christine Kelly of the OSU College of Engineering, will be genetically sequenced to determine if any variants of elevated concern are present in Corvallis, Bethel added.

OSU researchers have conducted weekly testing of Corvallis community wastewater since May 2020. Genetic evidence of the virus is shed by people who are infected, and the wastewater findings have been consistent with TRACE prevalence estimates.

The prevalence estimates are based on a variety of inputs, including test sensitivity, number of people tested and where those testing positive live.

“Better understanding the level of community protection is important, as it can inform evidence-based policy decisions around risk,” said April Holland, Benton County public health administrator. “Adding antibody detection to TRACE’s testing efforts is an exciting development, particularly with a simple saliva-based collection process that can be broadly deployed. Most COVID-19 antibody tests require a blood sample, which understandably poses a challenge to community participation.”

Over the weekend of June 5 and 6, teams of TRACE Community field workers will fan out to 30 neighborhoods and invite members of each household they visit to participate in the study. Those who choose to take part will be asked to provide information such as their name and date of birth; fill out a simple consent form; and answer a few confidential, health-related questions.

In Corvallis, where the participation percentage has consistently been around 70%, a weekend of door-to-door visits can produce nearly 700 samples.

“It is our hope that community members will continue to participate at a high rate,” said Javier Nieto, dean of OSU’s College of Public Health and Human Sciences and one of the TRACE-COVID-19 project’s principal research investigators. “Participation is extremely important so we can calculate a valid estimate of prevalence in the community. We really hope people won’t say no because they were recently vaccinated or tested.”

Participants will be given a nasal-swab test kit that they administer to themselves and to their minor children if they want them to take part. Participants will also be invited to provide a saliva sample in a tube for antibody testing; less than one-half of a teaspoon is needed.

TRACE field staff will wait outside at each home, and the participants will place the completed test kits outside their front door. The field workers will leave participants with information about the project and how they will receive their nasal swab results – available within a few days – as well as health guidance from the Benton County Health Department and the Centers for Disease Control and Prevention.

Participants will receive their nasal swab results and those of their minor children by secure email with receipt by mail as a backup. Personal information will be safeguarded.

The TRACE project is a collaboration of five OSU colleges – Science, Agricultural Sciences, the Carlson College of Veterinary Medicine, Engineering, and Public Health and Human Sciences – plus the OSU Center for Genome Research and Biocomputing.

TRACE-COVID-19 has received funding from OSU, the David and Lucile Packard Foundation, PacificSource Health Plans and the Oregon Health Authority and has been aided by work from the OSU Foundation and the OSU Alumni Association.

“OSU’s TRACE team has been a key partner in Oregon’s COVID-19 response,” said Dr. Melissa Sutton, OHA’s medical director for respiratory viral pathogens. “Their findings will further our understanding of how COVID-19 has spread throughout Benton County, and how many people in Benton County have been infected with, and vaccinated for, COVID-19.”

TRACE-COVID-19 works in partnership with the Benton County Health Department in Corvallis and other county health departments around the state. TRACE Community has also conducted sampling in Bend, Newport, Hermiston, Eugene and Redmond.

The nasal swab diagnostic testing component of TRACE operates through a partnership between the Oregon Veterinary Diagnostic Laboratory, which is located at OSU, and Willamette Valley Toxicology.

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