COVID-19 Testing
Testing is the biggest challenge in the US. New tests are being launched every day.
Here’s how to think about it.
RT-PCR (Reverse Transcription – Polymerase Chain Reaction)
- Gold standard for accurately diagnosing COVID-19, per CDC and FDA
- Detects presence or lack of virus RNA in a test sample
- Tests run on large, expensive instruments in highly certified diagnostic labs
- Samples can be collected using various devices across the anatomy
Examples:
+ Nasopharyngeal sample collected using a long flocked swab.
+ Short swabs of the front of the nostril and mid-nostril, per UnitedHealth Group study.
+ New Saliva sample collection addresses supply chain challenges.
POCT (Point of Care Tests) Molecular Diagnostic Tests
- Tests use molecular diagnostics to detect presence of genetic material from virus
- Tests are run on analyzers about the size of a toaster in the hospital or physician’s office
- Samples are run one at a time and results can be obtained in five minutes to one hour
Examples:
+ Detect COVID-19 in as little as 5 minutes.
+ Combating the coronavirus pandemic – rapid test for COVID-19.
POCT (Point of Care Tests) Molecular Diagnostic Tests
- Tests use molecular diagnostics to detect presence of genetic material from virus
- Tests are run on analyzers about the size of a toaster in the hospital or physician’s office
- Samples are run one-at-a-time and results can be obtained in five minutes to one hour
Examples:
+ Detect COVID-19 in as little as 5 minutes.
+ Combating the coronavirus pandemic – rapid test for COVID-19.
Semi-Quantitative Serology (IgM/IgG/IgA) Tests
- Determines whether an Immunoglobulin (IgG/IgM/IgA) antibody is present
- Test is conducted on standard ELISA laboratory analyzers
- Requires blood samples collected via venipuncture or fingerstick
- Tests are more accurate and more expensive than rapid test strips
Examples:
+ Description of serology assays.
+ Major lab offering.
+ BioIQ Offering.
Rapid IgG/IgM Tests
- Determines whether an immunoglobulin (IgG/IgM) antibody is present
- Immunoglobin protects against bacterial and viral infections
- Tests provide results from a drop of blood in as little as five minutes
- Tests are less accurate than RT-PCR tests and cannot be used to diagnose COVID-19.
- Tests are less expensive than tests run on laboratory equipment (RT-PCR or POCT)
Examples:
+ UK coronavirus home testing to be made available to millions – The Guardian.
+ Test widely used in South Korea.
Rapid IgG/IgM Tests
- Determines whether an immunoglobulin (IgG/IgM) antibody is present
- Immunoglobin protects against bacterial and viral infections
- Tests provide results from a drop of blood in as little as five minutes
- Tests are less accurate than RT-PCR tests and cannot be used to diagnose COVID-19
- Tests are less expensive than tests run on laboratory equipment (RT-PCR or POCT)
Examples:
+ UK coronavirus home testing to be made available to millions – The Guardian.
+ Test widely used in South Korea.
Do I have the virus?
RT-PCR Testing
Lab or Point of Care Testing
Sample collection types include:
- Nasopharyngeal flocked swab
- Mid-nostril short swab (mid-turbinate)
- Nostril swab (anterior nares)
- Saliva specimen
Did I have the virus?
Antibody Testing (IgM/IgG)
Lab or Rapid Test Strip
Sample collection types include:
- Venipuncture (whole blood or serum)
- Fingerstick
Sensitivity of Key Biomarkers for COVID-19
Testing Models
These tests all have beneficial clinical uses and can be done in a variety of settings for a variety of purposes. They can even be combined depending upon what you would like to test for. Testing models and locations include:
Home Self-Collection
Saliva or nasal samples are collected with or without telehealth oversight and sent to the lab for RT-PCR testing.
Testing Tent
A sample is collected and sent to the lab for RT-PCR testing or a POCT test is completed.
Drive-Through
Can be a combination of rapid IgG/IgM and/or sample collection for RT-PCR testing.
Home Visit
A sample is collected by a clinician and sent to the lab for RT-PCR testing.
Worksite
Nurses or clinicians leverage worksite areas or occupational medicine clinics for sample collection for RT-PCR and/or antibody testing.
Test Comparison
| Test | Description | Source Technician | Uses | Pros | Cons | Notes |
| RT-PCR (Reverse Transcriptase – Polymerase Chain Reaction) | Extracts and amplifies the amount of RNA, then compares it to standard | Nasal/oral swab (flocked or newer synthetic) Bronchia/alveolar lavage Trained clinican | Acute illness screening and testing Virus exposure, carriage | Gold standard Lab high sensitivity Clinical high sensitivity Experience with test | Turnaround time Equipment and skilled staff needed Central lab needed Expensive | Specificity unknown in current clinical situations – concern re: false negative rate Working on alternative collection methods |
| Point of Care Molecular Testing (POCT) | Extracts and amplifies the amount of RNA, then compares it to standard | Nasal/oral swab (flocked or newer synthetic) Bronchia/alveolar lavage | Acute illness screening and testing Virus exposure, carriage
| Utilizes recommended molecular diagnostic testing principles Results obtained in 15-45 minutes | Limited sensitivity/specificity Serial testing limits capacity to 1-4 tests per hour | Leading devices have generated concerns regarding safety (to lab personnel) and accuracy |
| Rapid Point of Care Antibody Testing (POCT) | IgM/IgG qualitative antigen testing (various tests in development) Use drop of blood (from a fingerstick) in as little as five minutes | Variable sources; blood at the moment is main source Point-of-care admin and result | Acute illness screening and testing, indicates if you have been exposed | Quick Rapid turnaround Doctor’s office or locality based testing Potentially scalable at clinician-office level | No experience at scale Unknown clinical sensitivity and specificity Not applicable for “immunity” testing | Can be used as a screening test to be followed with confirmatory test if needed |
| Semi-Quantitative Antibody Testing | Blood/serum assay for IgM and/or IgG using serology or EUSA testing | Blood or serum Technician/physician | Acute exposure and illness | Can test immune response and suggest acute reason for illness May suggest immunity as research evolves and with serial testing over time | Actual concurrent viral load and infectability uncertain | Immunity may not be long lasting |
