Could a different testing strategy reduce healthcare workers’ isolation after unprotected exposure to a confirmed case of COVID-19?

RI-MUHC study suggests appropriate testing could bring down isolation from 14 to 7 days

The second wave of COVID-19 is putting enormous pressure on the healthcare system. This is a time when we need our healthcare workers the most, and removing frontline personnel for two weeks after a high-risk exposure to COVID-19 puts an additional strain on the system. Dr. Benjamin Smith, a scientist and associate director of the Centre for Outcomes Research and Evaluation at the Research Institute of the McGill University Health Centre (RI-MUHC), sought to determine if there was prospective data to back up that strategy. He conducted a study with a team of RI-MUHC scientists and MUHC infection control specialists.

The preliminary results of the study, published online in the Infection Control & Hospital Epidemiology journal, provide evidence that a simple infection control strategy consisting of symptom-triggered testing from day 0 to 7 post high-risk exposure to COVID-19, followed by a standard home-based test on day 7, could shorten by 50 percent the self-isolation period and help protect patients, healthcare workers and other essential service providers.

Funded by MI4 (McGill Interdisciplinary Initiative in Infection and Immunity) with the support of the MUHC Foundation and by the Rossy Foundation, the study involved MUHC and Montreal area healthcare workers who were advised by their Infection Control or Health Prevention and Promotion officer to self-isolate following a high-risk SARS-CoV-2 exposure. From day 0 to 7 post-exposure, they were advised to seek SARS-CoV-2 RNA testing if symptomatic, and then had standardized home-based nasopharyngeal swab and saliva testing on day 7.

The results show that among 30 healthcare workers enrolled between May and October 2020, three were diagnosed with COVID-19 by day 14 post-exposure, with all cases detected by day 7. The negative predictive value for subsequent clinical COVID-19 or asymptomatic SARS-CoV-2 detection by day 14 was 100 percent, meaning that all those who tested negative at day 7 did not develop COVID-19 by day 14. Standardized SARS-CoV-2 testing at day 9, 10 and 14 also confirmed that none of these healthcare workers were asymptomatic carriers of the virus.

“Our study suggests that a simple testing strategy may allow for the early detection of healthcare workers who will develop COVID-19 after high-risk exposure. It’s a promising result. If these findings are confirmed as we test a larger number of people, this strategy could significantly shorten the self-isolation duration required for healthcare workers,” says Dr. Smith.

If you are a healthcare worker from the Montreal-area who has recently self-isolated due to a COVID-19 exposure and wish to take part in the study, please email [email protected].