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VUMC team screens high school for SARS-CoV-2 asymptomatic infections

Apr. 29, 2021, 9:31 AM


by Paul Govern

Under the SARS-CoV-2 Return to School Saliva Opt-in Screening Study, which began last November at University School of Nashville, a research team from Vanderbilt University Medical Center is testing a solution for efficient asymptomatic disease surveillance and control.

“With spread by those without symptoms having been shown to account for at least half of all cases of COVID, and the emergence of viral variants that transmit more efficiently, there’s likely to be a wider role ahead for routine testing of asymptomatic individuals,” said infectious diseases specialist Simon Mallal, MBBS, professor of Medicine at VUMC.

Simon Mallal, MBBS

“Vaccination is a game changer but is likely more effective in preventing symptoms and interrupting the chain of transmission than preventing COVID infection itself. While studies have shown promising persistence in antibody responses following full vaccination, the absolute duration of protection and the full correlates of protective immunity are currently not known,” Mallal said.

At USN, an independent day school with a current enrollment of 1,083 students in grades K-12, the VUMC team has arranged for weekly saliva collection and pooled testing. The study is currently open to high school students, faculty and staff.

According to Mallal, asymptomatic pooled saliva testing was the obvious choice for bolstering COVID-19 prevention efforts at USN. It’s relatively inexpensive, and specimens can be collected at home by the participants themselves, for drop-off at school in the morning.

“What we’re trying to do is decrease the burden of testing, the time, people and money required, particularly in the pre- and post-lab phase of testing, and to exploit automation in the laboratory and informatics tools throughout the process to maintain strict data and sample integrity,” he said.

Online participant intake, electronic consent and automated results reporting are powered by REDCap, or Research Electronic Data Capture, a secure web application developed at VUMC and today used around the world for online and offline data capture for clinical and translational research.

Participants use a smart-phone app called MyCap, also developed at VUMC, to scan barcodes on the bottom of specimen vials, and to answer questions about any symptoms they may have had recently. In the lab, specimen vials are placed in racks so that machines can uncap them, read the barcodes and process and track the samples. With a highly sensitive method called digital droplet polymerase chain reaction, the machine tests pooled samples for SARS-CoV-2 nucleic acid strands (RNA).

Barcoding allows results to flow directly from the lab apparatus to REDCap, and in turn to study participants, who receive same-day negative results via MyCap.

“REDCap in concert with MyCap is proving to be a wonderful way of engaging participants, returning feedback quickly to students, their parents and the other participants, and getting everyone’s trust in the medical research process,” Mallal said.

Positive results from pooled samples are reported to the USN health services team, triggering individual tests by a clinical laboratory. Following any positive individual results, contact tracing by USN involves the option of individual testing of household members and their immediate contacts, augmented by genetic sequencing of virus samples.

In all, among 395 high school students, the school has seen 37 cases of COVID-19. There are currently 393 participants in the study. Among study participants and their contacts, three cases of COVID-19 have been identified via the study protocol. All three involved people who had symptoms at the time of saliva collection.

“With ongoing viral replication in the community, viruses can mutate, and vaccines could become less effective with time,” said Elizabeth Phillips, MD, professor of Medicine, who co-leads the study with Mallal. “The best defense against this is a multipronged approach that includes mass vaccination, continued adherence to masking, handwashing and distancing, and early detection of replicative virus in the community.”

The study team also includes, from USN, Margee Brennan, MD, and Jennifer Aaron, NP, and, from VUMC, Rama Gangula, MS, Suman Pakala, ME, Bev Woodward, MSN, RN, Amy Kerrigan, MSN, RN, David Haas, MD, Abha Chopra, PhD, Loren Lipworth ScD, Jonathan Swafford and Paul Harris, PhD.

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