As COVID-19 cases surge in the D.C. area, GDS has partnered with CIAN Diagnostics to provide pooled COVID-19 testing for community members. The school expressed that the aim of the new partnership is to allow more frequent and cost-effective testing while decreasing interruption to the school day.
The decision to switch from Children’s National Hospital to CIAN for COVID-19 testing was announced in an email to the GDS community on Nov. 15 and was made because Children’s “could not accommodate the need we had in terms of numbers,” according to Vinita Ahuja, GDS’ director of strategic programs, who has managed the school’s virus response.
Senior Celia Johnson, who has been tested under both testing programs, said the new program was “a very quick and easy experience,” although some students experienced long lines with CIAN early on.
Children’s was only able to conduct 300 total COVID-19 tests per day. CIAN Diagnostics, a laboratory based in Frederick, Maryland, has the capacity to run 3,000 tests per day, according to Dr. James McArdle, the company’s chief scientific officer. Ahuja said in an interview, “Given the rising case numbers in the region, we wanted to be able to do more frequent testing.”
An email to the GDS community about the school’s new testing protocols explained that in pooled testing, multiple individuals’ nasal swabs are combined and run on the same test. If the pool comes back positive, CIAN will do “re-flex” testing in which they will individually re-test each sample in the pool, without having people re-swab their noses. Before switching testing partners, students were scheduled to be tested once every other week. Now, all students and faculty are tested weekly.
“It’s good that they changed it to every week,” freshman Maya Cruz-Hubbard, who hasn’t yet been tested at GDS, said of testing in an interview with the Bit. “From what I’ve heard, it’s uncomfortable, but I think it will be worth it to know.”
Bill Wallace, a science teacher, said that the idea of pooled testing assumes that the vast majority of people you are testing don’t have the virus.
Duke University implemented pooled COVID-19 testing at a large scale, which assisted them in remaining open for the first semester. According to Thomas Denny, a professor of medicine and the chief operating officer of the Duke Human Vaccine Institute, the decision to do pooled testing at Duke University was made because the institution is mainly testing an asymptomatic community. He said that when you test an asymptomatic community, typically “the number of positives you have are low frequency.”
The Centers for Disease Control and Prevention’s Morbidity and Mortality Weekly Report says that Duke University identified 84 positive cases, with varying methods, including pooled testing, entry testing, contact tracing, and symptom monitoring. 34.5 percent of total cases were identified through pooled testing. Denny said that, based on information from contact tracing, Duke had “no in-class transmission the whole semester” and that costs have been decreased by 80 percent as a result of pooled testing.
While different types of COVID-19 tests are available, PCR testing, which searches for the messenger RNA (mRNA) of the virus, has been deemed to be more sensitive than other types of tests, such as antigen testing, according to the CDC’s “Interim Guidance for Antigen Testing for SARS-CoV-2.” (mRNA are genetic molecules that produce proteins.) Individual antigen tests range in price from five to 50 dollars, according to the CDC, while Ahuja said the cost of individual PCR tests is about 119 dollars. Denny stated that PCR testing is “the gold standard.” GDS’ testing partner, CIAN Diagnostics, is doing PCR testing for the GDS community.
A driving force for switching to pooled COVID-19 testing is the cost, as Ahuja told the Bit that GDS is paying for all testing. The weekly cost of testing everyone in the community individually would come to around 163,000 dollars. Pooling COVID-19 tests allows for this number to drop drastically. Ahuja said that each pool costs between 120 and 304 dollars. Cost varies based on the number of people in a pool, with individual costs now ranging from 19 to 30 dollars.
GDS’ pools contain a maximum of sixteen individuals. Duke University, which developed its own COVID-19 test, is performing testing in pools of five individuals. When asked about the possibility of a larger pool affecting accuracy of the test, Ahuja said that “the more you put in a pool, the more possibility there is for a false negative.”
However, CIAN Diagnostics is able to perform testing on pools of four to twenty people “and not lose sensitivity and specificity,” according to McArdle, referring to the ability of a test to correctly identify patients with a disease and those without the disease, respectively. Thomas Denny of Duke University said that when they used a commercial test, they found that the same samples could get accurate results in pools of 5 and 10, but not 20 individuals.
GDS has said that results should be available within 24 to 48 hours. McArdle said the “pooled testing process is more time-consuming” because the samples within each pool must be mixed prior to the tests being run. Only those who test positive will be notified.
In an interview on Dec. 4, Ahuja said the school has “tried really hard to share that it’s a weekly program and not everybody has signed up for every week.”
Celia Johnson said her “major complaint is with the testing scheduling system. It’s like this online portal and you have to schedule all of your testing sessions at once. There is just a lot of scrolling. It seems like an extremely inefficient way to do that.”
Although frequent testing may add surveillance and an extra layer of protection, Denny made it clear that “testing does not replace the need to mask and socially distance.” In its plan for reopening, GDS emphasized the importance of those two measures.
When testing more frequently, Denny said, “you enhance your ability to pick out a positive.” Turning to pooled COVID-19 testing could allow for more accurate and cost-effective testing while the pandemic continues to worsen, albeit with a vaccine-induced end in sight.