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Coronavirus | U.S. universities rely on rapid tests for safe campus return

Quick fix: Rapid antigen tests are quick and cost less, therefore allowing frequent testing on a large scale.  

As educational institutions in India are set to open to students under Unlock-5, colleges and universities can make students return safely by following the example of University of Illinois at Urbana-Champaign in the U.S. and other American universities.

To ensure safe return to campus, the University of Illinois at Urbana-Champaign began an ambitious initiative in mid-August to test for free all students, faculty and staff for novel coronavirus using a rapid saliva-based test that was developed in-house. Testing of faculty and staff began in July.

Frequent testing

Despite the low sensitivity compared with RT-PCR, rapid antigen tests were preferred as they were quick, cost less and therefore allowed frequent testing on a large scale. To compensate for the low sensitivity of rapid tests, all the students, faculty and staff were compulsorily required to get tested twice a week.

Rochelle P. Walensky and her collaborators from Massachusetts General Hospital, Boston, modelled different scenarios to safely re-open campuses. They report in JAMA Network Open that “symptom-based screening alone is not sufficient to contain an outbreak. Safe reopening of campuses in fall 2020 may require screening every two days, besides following good prevention practices”. The symptom-based approach will also miss detecting asymptomatic and presymptomatic cases, which form a majority according to a paper in the journal PNAS.

When a student tests positive, he/she is informed of the result and asked to isolate, and all contacts who had spent more than 15 minutes within six feet distance from the index case are traced and asked to quarantine.

While just 311 fresh cases were detected from August 17-23, a spike in fresh cases was seen in end-August and early-September when 549 new cases were detected in just three days. The university was forced to undertake partial lockdown on student activities. The spike in fresh cases attracted huge media criticism, and Nigel Goldenfeld and Sergei Maslov who were involved in the programme were pilloried for the outbreak.

Besides the students testing positive at the time of entry, it was found that students who tested positive violated isolation and partied leading to large virus spread. The testing programme was based on modelling studies that took into account how students socialise, including attending parties without wearing a mask. “We modelled that they were going to go to parties and that they probably weren’t going to wear masks, and it would lead to some level of transmission. What we didn’t model for is that people would choose to go to a party if they knew that they were positive,” Martin Burke from the University’s Department of Chemistry who helped develop the saliva test told Nature. “The overwhelming majority of our students have done a great job, but unfortunately, a small number of students chose to make very bad decisions that led to a rise in cases.”

Improvements to note

Following some restrictions on student gatherings for two weeks, fresh cases reported have since dropped — from 230 cases on August 31 (test positivity rate of 1.34%) to 25 cases on October 6 (test positivity rate of 0.24%). When restrictions were loosened students once again returned to more social engagement leading to 62 fresh cases on September 22, the highest since September 8. However, fresh cases have reduced since then.

“It’s good to praise improvements. Once campus reopened, we had no choice but to do everything we could to reduce spread. The restrictions helped. But we need to avoid equating relative improvement with absolute success. The plan was not and still is not a success,” Daniel Simons, a cognitive psychology Professor at the university tweeted. “We shouldn’t treat an improvement relative to an awful situation as success, just as it’s wrong to say things are great here because they’re better here than at other universities that have done less testing.”

Model system

Up to 10,000 students are tested each day and totally over 4,92,000 tests have been done till October 6 with a seven-day test positivity rate of 0.28%. “Surveillance and rapid response are part of any reasonable plan. That they did this and it worked was a huge success,” Carl T. Bergstrom from the University of Washington tweeted.

Today, the University’s mass testing programme is being touted as a model system and many universities — Yale University, Indiana University, Harvard University, University of Georgia, University of Wisconsin — have emulated it.

Dr. Giridhara Babu, epidemiologist from the Public Health Foundation of India, Bengaluru, is not upbeat in replicating this strategy to detect cases and break the transmission chain when students return to colleges/universities. In an email to The Hindu, he says: “It is important not to blindly increase the testing numbers without the end goal. In public health, it is also important to ensure that necessary interventions such as isolation centres which provide the standard of care are arranged before scaling up universal testing when a screening mechanism is implemented in universities/colleges.” He is also concerned about the cost of using rapid tests repeatedly to detect cases. “With the current costs, I am also not sure if this strategy can be employed at scale in India,” he says.

The other side

Despite the advantages of detecting asymptomatic cases early and thereby breaking the transmission chain, he is in favour of testing those who show symptoms. “From decreasing mortality, the mainstay of testing will still be to find those who have symptoms and test them rather than randomly testing everyone and every time. Testing is only a tool to know if transmission is present, that too an imperfect one. It is not mere numbers, improving the overall testing strategy of finding those who have symptoms, through syndromic approach might be more beneficial in India,” Dr. Babu says.


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Printable version | Nov 30, 2021 12:25:22 AM | https://www.thehindu.com/sci-tech/science/coronavirus-us-universities-rely-on-rapid-tests-for-safe-campus-return/article32822513.ece

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