Our Medical Advisory Services (MAS) team of physicians is the foundation of our Safe at Work System. These occupational health and safety experts provide your organization with evidence-based guidance to develop and implement time-relevant COVID-19 strategies. The following primer, compiled by the MAS team, was designed to help you develop a COVID-19 testing strategy for your organization
Interested in learning more about rapid testing in practice? Our chief medical officer, Dr. Peter Nord, explores the accounts of two pioneers in the podcast below. For complete show notes and a full episode transcript, visit www.eatmovethinkpodcast.com.
Businesses and employers have a large responsibility in preventing and slowing the spread of COVID-19 within the workplace. An employer’s COVID-19 strategy and control plan should take into account testing for COVID-19 infection along with contact tracing and symptom screening. These work together to identify workers at risk of COVID-19 infection so that actions can be taken to slow and stop the spread within the workplace. A good analogy used by our MAS physicians is considering each component of a COVID-19 control plan as individual layers of swiss cheese. Some layers can provide additional protection, like viral testing, but will not eliminate risk and should be evaluated from both a cost and effectiveness standpoint. A comprehensive COVID-19 strategy and control plan integrates different layers of protection to keep employees safe as they return to work.
Before integrating testing into your COVID-19 control plan, it is important to understand the different types of tests that have been approved.
Sensitivity and specificity are terms used to describe the accuracy of a medical diagnostic test. The sensitivity can be thought of as a “True Positive” test, as in the test’s ability to correctly identify a positive person as positive. If the test does not correctly identify a positive person as positive, it is considered a false negative. For example, if a test’s sensitivity is 98% then its rate of false negatives is 2%.
Specificity can be thought of as a “True Negative” test, as in the test’s ability to correctly identify a negative person. If the test does not correctly identify the negative person as negative, it is considered a false positive. For example, if a test’s specificity is 92%, its rate of false positives is 8%.
Ultimately, for employers, it is important to reduce the frequency of false negatives since organizations want to ensure that no one with an infectious disease enters the workplace. That’s why it’s important to have a high sensitivity to reduce the frequency of false negatives. On the downside, you may end up sending an employee home who subsequently tests negative on the more specific test.
A health practitioner typically obtains the specimen for testing using a sterile nylon swab. The most common swab amongst tests is the nasopharyngeal (NP) swab, which is inserted up the nostril to the back of the nasopharynx (hence the name) and rotated to collect the specimen. Some testing platforms have been approved for the use of a nasal swab which is similar to the NP but does not need to be pushed as far back and the specimen can be collected from the nasal wall. Other platforms accept a throat swab in which the back of the throat is swabbed through the mouth. Some procedures will require the combination of techniques using the same swab with the throat being the first point of collection. Read on to discover which specimen collection technique is used for each test.
There are three main categories of testing that the MAS team recommends considering when developing your COVID-19 testing strategy:
Employees should be screened daily for COVID-19 symptoms prior to entering the workplace. If the outcome of this screening indicates that the employee is symptomatic, they should proceed to their nearest testing centre. Should symptoms arise while they’re on-site at the workplace, employees should be immediately isolated and sent for testing. Symptomatic testing must be performed at a publicly funded assessment centre that uses a confirmatory Polymerase Chain Reaction (PCR) test.
Recommended Testing Frequency
For symptomatic testing, the testing frequency is an immediate PCR test upon symptom onset.
Similar to the above scenario, if employees are suspected of exposure to COVID-19, they should seek a PCR test provided by public health. However, MAS also recommends multiple tests at different points in time (called serial testing) to more accurately monitor exposed employees for infection. Serial testing is not publicly funded but can be supplied privately by Medcan.
Recommended Testing Frequency
MAS recommends to align the serial testing frequency with the change in testing sensitivity. A PCR test has the highest sensitivity five to eight days after exposure. PCR test sensitivity is lowest for individuals between zero and two days of initial exposure with a testing sensitivity of only two per cent. By day five sensitivity increases to 50% after the initial exposure, and then to 90% by day eight. Therefore, a PCR test frequency of every five to seven days during the 14-day isolation period is recommended.
Asymptomatic individuals have the ability to spread COVID-19. Viral testing can identify these individuals and proactively isolate them before they transmit the virus to others and risk the safety of the workplace. The need for proactive testing is heightened in workplaces where physical distancing is difficult and where workers are within two meters of each other for 15 minutes or longer. The need for proactive testing is also heightened for workplaces geographically situated in communities with a high number of positive cases.
As an employer, there are three testing options for proactive testing to prevent transmission:
While this testing isn’t currently funded by the government, asymptomatic testing to prevent the transmission of COVID-19 can be conducted privately. Medcan has the ability to provide your organization PCR (molecular) laboratory testing with next-day results and is seeking to soon provide rapid antigen testing as well.
Recommended Testing Frequency
For proactive and regular screening of asymptomatic employees to reduce potential transmission, testing can be done twice a week, or weekly. Currently, in long-term care facilities, employees are tested once per week, and the Creative Destructive Lab pilot for rapid antigen testing has recommended a testing rate of twice per week. Daily testing is not typically recommended because if an individual is exposed to COVID-19, there is little change in the amount of virus present in their body within 24 hours. It normally takes up to five days for the amount of virus in the body to be significant enough to be detectable by the test. Finally, the frequency should also depend on the availability of testing, the current growth in positive cases in the surrounding community, how many employees tested positive during previous rounds of testing, and the organization’s experience with outbreaks.
Below is a helpful table comparing some of the different viral testing platforms that are currently approved by Health Canada. This list contains the most current testing platforms an organization can consider for their testing plan.
Prior to an organization testing a large proportion of asymptomatic employees, it is important to have a robust control plan and contact tracing program in place in the event of a laboratory-confirmed positive case. Medcan’s MAS team can help your organization in this regard. First, the organization must identify any close contacts of the confirmed positive case and have them tested using molecular PCR testing at a laboratory. If it is too difficult to determine specific close contacts, broader testing may be necessary.
Your organization must be prepared to modify operations based on a positive test result to manage the higher risk of transmission. This can include increasing sanitization of the workplace, changing shift schedules, and increasing point-of-care testing frequency.
Testing is not recommended as a tool to determine when an employee should return to work. PCR testing has detected the shedding of the virus up to four to six weeks since initial infection, but these are just pieces of dead virus and are not contagious. Therefore, for non-healthcare workers, the CDC recommends a symptom-based strategy for determining return to work criteria of at least 10 days from symptom onset and if no symptoms, 10 days from the date of their first positive PCR test, and at least 24 hours since their last fever without the use of fever reducing medications. If the COVID-19 is severe and the patient is in the ICU, then the isolation should be 20 days instead of 10 days.
It should be noted that with the rise of new COVID-19 variants, certain jurisdictions have different directives on the period of isolation. The MAS team recommends consulting your local public health guidelines for mandatory isolation periods.
Each organization is going to have different workplace considerations. This primer is a great first step to better understanding testing options and standards. To take the next step and understand what will work best for your workplace, we recommend booking a consultation with a member of our MAS team.
To learn more about Medcan’s Medical Advisory Services, or to request a co-branded version of this primer geared to your employees, send a note to email@example.com.