How much were University of Toronto students registered for in-person classes in last autumn exposed to COVID-19? An ongoing study by public health researchers at UofT intends to find out.
The study—a collaboration between scientists at the Dalla Lana School of Public Health, UofT’s Faculty of Medicine, and Mt. Sinai Hospital—aims to measure the prevalence of antibodies for SARS-CoV-2, the virus that causes the COVID-19 disease, among students.
Antibodies are proteins that a patient’s body produces as part of the immune response to a foreign pathogen. The presence of SARS-CoV-2 antibodies in a volunteer’s blood sample serves as a hallmark that the patient has been exposed to COVID-19.
Nearly one in five carriers of COVID-19 are asymptomatic, according to the conclusions of a December 11 study reported by Nature. While these carriers are less likely to spread the virus than symptomatic patients, they are more likely to spend time in physical contact with others instead of isolating at home. Therefore, testing for antibodies provides researchers with a clearer picture of COVID-19 exposure within a community, as it identifies asymptomatic cases.
The UofT public health researchers note that the ultimate results of their study on COVID-19 exposure to students who have taken in-person classes may shape policymaking decisions on “UofT on-campus activities over the coming months and into the next academic year.”
University reports two previous outbreaks of COVID-19 on campus, but may be underreporting
In a December announcement, The Faculty of Arts & Science moved all classes online for the Winter semester, “with the exception of courses approved by the Dean’s Office for in-person delivery.” Previously, the Fall 2020 semester provided students with a mixture of online and in-person classes.
The researchers plan to compare the exposure of UofT students to COVID-19 in the fall semester to exposure in the winter. Since March, the University of Toronto has reported 140 cases of COVID-19 “by members of the U of T community.” The records include two confirmed COVID-19 outbreaks on the University’s three campuses.
However, these records may underrepresent the number of COVID-19 cases within the UofT student community. The statistics only include patients who voluntarily reported their status “to the Occupational Health & Safety Office that they have tested positive and have been on a campus recently,” according to the dashboard. Cases among contractors are also excluded from the counts, notes the webpage.
The public health study at UofT aims to bridge the gap on the absence of data on COVID-19.
How researchers plan to find more accurate numbers on COVID-19 exposure at UofT
The UofT public health study aims to uncover more accurate numbers by blood testing student volunteers, with the goal of testing a third of eligible students for the study from December 2 to 22. The researchers also intend to collect data on the wellbeing and mental health of students.
Eligible students were at least 17 years old; residing in Ontario at the time of registration; and registered for any in-person activities on UofT campus in the autumn semester. These students received an email from Professor Sandy Welsh—UofT’s Vice-Provost, Students—for recruitment, with gift cards given as incentives.
UofT public health researchers aim to collect three blood samples from each volunteer during the study. The volunteers receive a blood collection kit, with instructions to collect blood with a finger prick. The volunteers will then submit their sample in a sealed container with a provided return label to a dropbox, available at all three UofT campuses, or request collection by a courier from the research team.
Participants will also answer questionnaires. For privacy, the researchers will anonymize the data from participants, and will not share information about individual students’ participation in the study with the University.
Limitations of the study
One limitation of the study is its exclusion of non-students, even if they are employees of the University, as noted by the researchers. The study will therefore not uncover data on the prevalence of COVID-19 among faculty and staff members, who are especially vulnerable to the virus due to age and jobs that require presence on-campus.
Furthermore, antibody tests face limitations regarding accuracy. According to an analysis of 38 COVID-19 studies by Cochrane, SARS-CoV-2 antibody tests are over 90 percent accurate after three weeks since exposure. However, these tests are only 30 percent accurate after one week since exposure, and 70 percent accurate after two. Two percent of tests also produced false positive results of COVID-19.
Nevertheless, the sample size of the UofT study and timeline of data collection will reduce the impact of these inaccuracies on the study’s conclusions.
Though volunteer registration is now closed, the UofT researchers will continue sample collection from recruits until January 2021. For volunteers who test positive for antibodies, Study Lead Dr. Shaza Fadel, assistant professor at the Dalla Lana School of Public Health, advises them to continue social distancing.
“The presence of antibodies doesn’t necessarily mean you are immune to COVID-19 right now,” she said. “We still don’t know how strong the antibody response needs to be, or how long it lasts, before an individual is immune.”
