Dear Brown Community Members,
Below, please find our weekly update on Brown’s testing program for COVID-19, with additional information and context to complement the data shared via our public dashboard:
Prior to reviewing the data from the past week, please read carefully the following update with important information from the Broad Institute, the testing laboratory in Cambridge, Mass., that processes the COVID-19 test samples collected at Brown:
Brown and other universities that work with the Broad Institute were notified Monday of a change the institute made to its process, which affected some test results that had previously yielded a classification of “positive.” Changes the Broad made late last month to increase the volume of tests it could process caused the tests to be slightly more sensitive. When a COVID-19 test is highly sensitive, that means that it can detect very tiny amounts of virus. In many cases, a very small amount of virus can be present because someone was exposed many days prior to testing, and they have only a small amount of virus left in their body. In other cases, it may be because someone was very recently exposed and has not yet made many copies of the virus. When the virus level is very low -- like in these examples -- the test itself can’t determine the reason why.
What the University’s routine COVID-19 testing programs looks for is evidence of active and transmissible disease. Now that the Broad testing process has become more sensitive, the institute has updated the threshold level of virus to call a test “positive.” For tests just below this threshold, they will be classified as “invalid” or “inconclusive” (meaning, there is an inability to determine if the result was positive or negative). When a COVID-19 test is performed, the Broad uses two “probes” to test for positive signals in each COVID-19 test sample. Until recently, the institute’s practice has been to report a positive result if either one of the two probes detects a COVID-19 signal (except for situations where the Broad invalidates the test if only one probe detects very low viral load). Brown and other universities were notified that, in consultation with the Massachusetts Department of Public Health, the institute will now report a positive result only when both probes signal positive. The institute has made this adjustment to balance sensitivity and specificity of the test.
The Broad Institute determined that before the sensitivity of their classifications changed, 0.25% of tests across approximately 200 college and university testing sites that read as positive should have been classified as “invalid” or “inconclusive.” The institute notified the University that 17 Brown community members — 6 employees and 11 students — had test results previously classified as positive from samples collected within a very specific and limited timeframe between Jan. 25 and Feb. 4 that are impacted by this change (the 17 were out of a total of 23,443 tests conducted at Brown over these 11 days). Those individuals have all been notified and instructed to retest, in accordance with medical guidance. We understand and regret any stress and inconvenience that these positive test results may have caused.
In addition to the impact on the individuals involved, the reclassification lowers Brown’s previously reported numbers of positive asymptomatic test results by 15 (two of these reclassified tests are from the week we are reporting on in this update). Last week’s total number of positive results since Aug. 24 is therefore 333, corrected from the previously reported 348. The specific corrections from the two prior weeks are as follows:
-- The week of Jan. 21 to Jan. 27 there were a total of 21 positive asymptomatic test results, adjusted from the earlier reported total of 34. The 21 were: 5 from employees, 6 from on-campus students and 10 from off-campus students.
-- The week of Jan. 28 to Feb. 3 there were a total of 11 positive asymptomatic test results, adjusted from the earlier reported total of 13. The 11 were: 2 from employees, 4 from on-campus students and 5 from off-campus students.
The Broad Institute has conducted more than 10 million COVID-19 tests since the onset of the pandemic, and we are confident that they are utilizing highly scientific and evidence-based standards in this work.
At Brown, since launching our routine testing program for the fall term on Aug. 24, we have conducted 226,243 asymptomatic tests to date. A total of 10,341 individuals have been tested in that timeframe, and the total number of positive test results is 342 (up 9 this week from a corrected total of 333 last week) — a prevalence rate of 3.3%.
Here are highlights of the testing program over the last seven days, Thursday, Feb. 4, through Wednesday, Feb. 10:
-- There have been 9 positive asymptomatic test results: 4 from employees, 2 from on-campus students and 3 from off-campus students. As a reminder, our student testing program includes undergraduate, graduate and medical students.
-- Over the past week, the employee asymptomatic positivity rate was 0.15%, and the student asymptomatic positivity rate was 0.04%. The Rhode Island positivity rate during this same time period was 3.03%.
-- The average turnaround time for asymptomatic test results during this period was 20 hours.
-- University Health Services conducted 16 symptomatic tests of students. Of these, none were positive for COVID-19. Exact results for symptomatic students who are tested by UHS are not reported (and do not appear on the public dashboard) to protect the confidentiality of the small numbers of students who are tested. We will report on ranges and any concerns regarding trends in these weekly summaries.
-- The University does not directly test symptomatic employees, as they receive health care from their individual providers. We do monitor employee absences due to COVID-19 — which can be for a range of reasons, including care of a child or family member or quarantine due to a known exposure — and the number of such absences for the most recent full work week was 14.
-- It is important to note that with regard to all positive cases, we have taken action consistent with our contact tracing protocols, COVID-19 Campus Safety Policy, isolation and quarantine procedures, and other measures outlined in Brown’s Plan for a Healthy and Safe 2020-21.
As a reminder, if you are currently being tested once a week and would like to change to twice a week, you are welcome to do so. Students can email [email protected] to make that change. Faculty and staff can email [email protected] for guidance on how to increase their testing frequency.
Please feel free to contact us with any questions or concerns. For questions or support regarding the testing program, students can contact the student testing support team (401-863-6500, [email protected]), and faculty and staff can contact the employee testing support team (401-368-4828, [email protected]).
Russell C. Carey
Executive Vice President, Planning and Policy