by Greg Lathan
President
During 2020, occupational screening to identify potential COVID-19 carriers was limited to monitoring employee body temperature in conjunction with administration of a questionnaire aimed at identifying employees who exhibited coronavirus symptoms (headache, loss taste/smell, sore throat, cough or gastrointestinal issues) or workers who had close contact with a potential coronavirus carrier.
Those employees were most likely then subjected to a Polymerase Chain Reaction (PCR) test through specimen collection via nasopharyngeal swabbing. Analytical results were typically available from an accredited laboratory within 3-7 days of testing. Although these screening techniques were the best tools available at the time, the 3-7 day delay for lab confirmation of suspected coronavirus carriers was problematic, since many employees who were quarantined were found not to be infected.
As Pfizer, Moderna and others release COVID vaccines to the general public over the next several months, rapid analytical tests which can be administered “on site” to identify employees who are COVID-19 carriers, will become imperative to “break the COVID transmission chain” in the workplace.
An employee who tests positive for COVID-19 may have been exposed 2-14 days earlier, with an average 5 day incubation period prior to testing positive. These infected individuals typically shed the virus and infect others approximately 48 hours prior to the onset of their COVID symptoms. The quarantine period for individuals who test positive for COVID was recently lowered from 14 days to 10 days by the CDC, following onset of COVID symptoms. Nine months into the COVID-19 pandemic, several testing methodologies have been developed and approved by the FDA for use or emergency use in the United States.
The Three Primary Types of Tests Available:
- PCR
- Antigen
- Antibody (IgM and IgG)
Summary and Comparison of Testing Methodologies
1.) Diagnostic Tests
Diagnostic tests include both molecular (PCR and lamp tests) and Antigen tests. PCR based tests have been the workhorse and the gold standard for COVID testing during 2020.
1a.) PCR Tests
PCR tests work by separating genetic material from a sample collected from the back of an individual’s nose or throat. This test is the primary source for the percentage of positive US COVID cases portrayed in the media, with results available from the lab in 3-7 days. In addition to the nasal or nasopharyngeal cotton swab sample collection based PCR tests, the FDA has also approved Emergency Use saliva based test collection. Rather than a nasal swab, patients spit an adequate amount of saliva into a container which is sent for analysis by an approved laboratory. The first such FDA approved test was from Vault Health in collaboration with Rutgers Laboratory. The major drawback to PCR tests is the time for evaluation by the lab, typically 3-7 days, requiring a potentially COVID negative employee to be unnecessarily quarantined while awaiting lab analysis. Since the PCR test identifies both active and inactive mRNA, it is important to note that infected employees typically may test positive via PCR for up to 90 days after symptoms first occur, long after they are no longer infected. However, during the asymptomatic phase of an infection, a PCR test will identify a COVID carrier earlier than a rapid diagnostic antigen test.
1b.) Antigen Tests
Antigen tests are commonly used to identify respiratory pathogens, such as influenza. Often called immunoassays, these tests detect the presence of a specific pathogen from a virus. These tests offer a distinct advantage in onsite occupational screening, since they are much quicker when providing results, many in as little as 15 minutes. However, although these tests provide almost immediate results, it takes a skilled professional to accurately interpret these results. If a symptomatic employee tests negative for COVID via the rapid Antigen test, 99% positive confirmation for coronavirus can be achieved by combining those results with a subsequent PCR test.
2.) Antibody Tests
Antibody tests are not useful for diagnosing active COVID-19 infections. They detect antibodies developed by the immune system in response to an infection. While antibodies are often present within 6-10 days from infection. it can take up to three weeks to develop antibodies in some cases. Antibody tests administered 7 days after infection may be negative because the body hasn’t had enough time to produce sufficient antibodies against the coronavirus. A positive antibody test also does not necessarily mean that a person is free from wearing PPE, especially masks or disregard physical distancing recommendation, as research on the duration of immunity to COVID-19 is not clear at the moment.
Frequent testing for COVID-19 in the workplace will be necessary as Americans return to work.
At the current time, rapid antigen tests seem to offer the best alternative for screening personnel. Given the delay time to receive PCR tests, coupled with their higher costs than the more rapid antigen test, they are less practical when frequent administration is required. Although antigen tests are slightly less sensitive than PCR tests, they can be administered more frequently, with results in minutes rather than days. For these reasons, rapid antigen tests appear to be much more practical and useful tool than PCR tests for identifying COVID workers on a routine basis (Mina, Parker, & Larremore, 2020).
How Can We Help?
The EI Group, Inc. (EI) can facilitate testing on a large scale with highly trained Occupational Health professionals. There are several tests on the market that EI can administer.
For PCR testing, the Everlywell PCR test costs $109 and returns results in 24-48 hours. The LabCorp Pixel costs $119 and also returns results in 24-48 hours. It has a sensitivity of 95% and specificity of 98%. If a nasal swab isn’t your thing, consider the Vault Health saliva based PCR test.
For Antigen testing, the Abbott BinaxNow is an antigen test with 97.1% sensitivity and 98.5% specificity. Similarly the BD Veritor™ Plus System is readily available and cost effective.
For Antibody testing, we love the LumiQuick test from Advnt Biotechnologies. Whichever testing methodology is right for you, EI can help. Call us today at (800) 717-3472.