| Literature DB >> 34176567 |
Sajjad Shirazi, Clark M Stanford, Lyndon F Cooper.
Abstract
BACKGROUND: The dental office potentially possesses all transmission risk factors for severe acute respiratory syndrome coronavirus 2. Anticipating the future widespread use of COVID-19 testing in dental offices, the authors wrote this article as a proactive effort to provide dental health care providers with current and necessary information surrounding the topic.Entities:
Keywords: COVID-19 testing; SARS-CoV-2; aerosols; antibody; antigen; dentistry; oral fluids; point-of-care testing; saliva; surveillance
Mesh:
Year: 2021 PMID: 34176567 PMCID: PMC8096195 DOI: 10.1016/j.adaj.2021.04.019
Source DB: PubMed Journal: J Am Dent Assoc ISSN: 0002-8177 Impact factor: 3.634
Figure 1Fundamentals of COVID-19 testing. A. COVID-19 biomolecules can be detected in oral fluids as well as other sites and specimens. A detailed description and comprehensive review of these specimens' characteristics and viral loads and detection rates of COVID-19 is provided by Shirazi and colleagues.B. Schematic representation of detection window for COVID-19 biomarkers. The best detection and testing time for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) RNA and antigen is up to 14 days from symptom onset. Immunoglobulin M (IgM) antibody against SARS-CoV-2 is detectable days after symptom onset, peaks during week 2, and will start to disappear at approximately week 4. Immunoglobulin G (IgG) against SARS-CoV-2 antibody will be detectable at approximately week 2 and persist for an unknown time. The duration of persistence of IgG antibody is not fully clear yet. C. COVID-19 biomarkers are detected with various laboratory methods that have different mechanism of action. Figure 2, Figure 3, Figure 4 include detailed description of each method. POC: Point-of-care.
Figure 2Mechanism of action of nucleic acid amplification tests (NAATs). NAATs generally require 5 steps, which are modified or merged in different NAATs. The 5 steps are lysis of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) viral particles in the sample; purification of the viral RNA; reverse transcription of the RNA to complementary DNA (cDNA), which produces DNA templates for the next step; thermocyclic or isothermal amplification of specific regions (target genes) of the cDNA using gene-specific primers, DNA polymerases, and probes to amplify only the selected region; and detection of the amplified cDNA, which can happen during or after step 4. The difference among various NAATs arise from modification of these steps. Some NAATs do not require separate lysis and purification steps, whereas some others merge reverse transcription and amplification. Analytical accuracy of COVID-19 NAATs depends mainly on the primer or probe design, and different assays use different primer or probe sets targeting different regions of the SARS-CoV-2 genome. Some NAATs, including isothermal methods, are authorized for point-of-care COVID-19 diagnostics and provide fast, sensitive, high-efficiency, and cost-effective results without need for specialized equipment.
Figure 3Mechanism of action of antigen tests. Point-of-care antigen tests typically are lateral flow assays and come with a test strip or cassette composed of multiple overlapping pads. The clinical sample needs to be placed in a tube containing the extraction reagent after collection, which disrupts the viral particle and exposes the viral proteins. Next, the sample is added to the sample pad, where it starts to travel via capillary action through the conjugate pad and conjugates with the fluorescence-labeled severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) detection antibody or the detector-antibody gold conjugate. Next, it flows through an analytical membrane striped with a capture antibody specified as the test line. Most tests include a control line after the test line to validate proper fluid flow and the activity of assay reagents. The final outcome might be read via an instrument or displayed as colored lines for naked-eye reading.
Figure 4Mechanism of action of antibody tests. The authorized point-of-care serologic tests commonly are based on lateral flow immunoassay, which detect binding antibodies. Lateral-flow immunoassays are composed of a cassette that encloses strip membranes. After the specimen is added to the sample pad, it moves forward by capillary action through the conjugated pad, where the present immunoglobulin G (IgG) and immunoglobulin M (IgM) antibodies in the sample interact with impeded gold conjugated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigens and rabbit-gold conjugated antibodies. The created antigen-antibody complexes move forward to the analytical membrane and bind antihuman IgG and IgM antibodies (capture antibodies) at the test line and get immobilized, whereas the rabbit-gold conjugate antibodies bind to antirabbit IgG antibodies at the control line and get immobilized. The result will be visible as colored lines owing to the accumulation of gold particles. Depending on whether the test is for IgM- or IgG-class antibodies or both, the test may show 1, 2, or 3 stripes.
Comparison of different testing strategies for COVID-19.
| CONSIDERATIONS FOR EACH STRATEGY | TESTING STRATEGY | ||
|---|---|---|---|
| Screening | Diagnostic | Surveillance | |
| For asymptomatic person without known or suspected exposure | Yes | No | NA |
| For symptomatic person or known or suspected exposure | No | Yes | NA |
| To characterize incidence and prevalence in the community | NA | NA | Yes |
| Results may be returned to people | Yes | Yes | No |
| Results are returned in aggregate to requesting institution | No | No | Yes |
| Results are reported to state public health department | Yes | Yes | If requested |
| Testing can be performed in a Clinical Laboratory Improvement Amendments-certified laboratory | Yes | Yes | Yes |
| Testing can be performed in a non Clinical Laboratory Improvement Amendments-certified laboratory | No | No | Yes |
| Test system must be Food and Drug Administration authorized or be offered under the policies in Food and Drug Administration’s guidance | Yes | Yes | No |
NA: Not applicable.
Crosstalk between test characteristics and test results.
| PRETEST PROBABILITY | or | POSITIVE PREDICTIVE VALUE | or | NEGATIVE PREDICTIVE VALUE | OUTCOME |
|---|---|---|---|---|---|
| Low | Low | High | Increased chance of true-negative or false-positive results | ||
| High | High | Low | Increased chance of true-positive or false-negative results |
Specificity and sensitivity of tests are not affected by the pretest probability.
Pretest probability affects predictive values.
Comparison of different testing options for COVID-19.
| DESCRIPTION | NUCLEIC ACID AMPLIFICATION TEST | ANTIGENT TEST | ANTIBODY TEST |
|---|---|---|---|
| Viral, molecular | Viral, immunoassay | Serologic, immunoassay | |
| Diagnostic | Diagnostic, screening | Screening | |
| Detect current infection | Detect current infection | Detect prior or recent infection | |
| Viral RNA | Viral structural proteins | Virus-specific antibodies | |
| Generally high | Moderate to high | Moderate to high | |
| High | High | High | |
| Differs by test | Relatively easy to use | Relatively easy to use | |
| 15 min to > 2 d | 15 min to > 2 d | 15 min to > 2 d | |
| Need thermal cycling—some are isothermal | Ambient | Ambient | |
| Quantitative or qualitative | Visual or instrument read | Visual or instrument read | |
| Some tests | Most tests | Some tests | |
| Very few, sample collection is possible at home for many tests | Some tests | No | |
| 1 d after infection to 14 d from symptom onset | 5-7 d from symptom onset | ≥ 15 d from symptom onset | |
| Moderate (≈ $100-$200) | Low (≈ $5-$50) | Moderate (≈ $100-$200) | |
| Nasopharyngeal, oropharyngeal, nasal, sputum, saliva | Nasopharyngeal, nasal | Whole blood, serum, plasma, fingerstick blood | |
| Viral transport medium or saline—nothing needed for some tests | Extraction medium | Anticoagulant—nothing needed for fingerstick tests | |
| High requirements for operators and laboratory conditions. High cost, complexity, and turnaround time | Less sensitive in the early stage of disease | Lower sensitivity and specificity. Cross-reactivity. Long window period |
Relationship between the results of antibody tests, antigen tests, NAATs,∗ and clinical manifestation of COVID-19.
| CLINICAL MANIFESTATION | NAAT RESULT | ANTIGEN TEST RESULT | SEROLOGIC TEST RESULT | RISK OF EXPERIENCING INFECTION TRANSMISSION | |
|---|---|---|---|---|---|
| Immunoglobulin M | Immunoglobulin G | ||||
| + | + | + | − | High | |
| + | + | + | + | High | |
| + | + | − | + | High | |
| + | + | − | − | High | |
| − | + | + | − | High | |
| − | + | − | + | High | |
| − | + | − | − | High | |
| + | − | + | + | Low | |
| + | − | − | − | Low | |
| − | − | − | + | Low | |
| − | − | + | + | Low | |
NAAT: Nucleic acid amplification test.
Available POC∗ molecular diagnostic tests for COVID-19.†
| PRODUCT | TEST AT HOME | ACCESSIBILITY | MULTIANALYTE | METHOD | RESULTS REPRESENTATION | SAMPLE TYPE | TARGET | PERFORMANCE EVIDENCE FOR SARS-CoV-2 | TIME TO RESULSTS |
|---|---|---|---|---|---|---|---|---|---|
| Yes | OTC home testing, health care provider | No | RT, | Qualitative, instrument read | Anterior nasal swab in adults (self-swabbing) or children ≥ 2 y of age (swabbed by an adult) | Nucleocapsid gene | LoD | ~ 20 min | |
| No | Health care provider | No | RT-PCR | Qualitative, visual read | Nasopharyngeal, anterior nasal, or Midturbinate swabs collected by a health care provider or anterior nasal or mid-turbinate swabs self-collected (by people aged ≥ 18 y, under the supervision of a health care provider) | Nucleocapsid gene | LoD: 435 copies/swab | ~ 30 min | |
| No | Health care provider | No | Real-time RT-PCR | Qualitative, instrument read | Nasopharyngeal, nasal, or mid-turbinate swab | Nucleocapsid gene, envelope protein gene | LoD: 5.4 x 103 RNA NAAT | 30 min for positives and ~ 45 min for negatives | |
| No | Health care provider | No | PCR and lateral flow | Qualitative, visual read | Clinician-collected nasal or nasal mid-turbinate swab samples or clinician-instructed self-collected (collected on site) nasal swab | Nucleocapsid gene | LoD: 200 copies/reaction. | ~ 30 min | |
| No | Health care provider | Yes,16 viruses and 4 bacteria | Real-time, nested multiplexed PCR | Qualitative, instrument read | Nasopharyngeal swab | Spike protein gene and membrane protein gene | Overall, 97.1% sensitivity and 99.3% specificity (prospective specimens) | ~ 45 min | |
| No | Health care provider | SARS-CoV-2, influenza A and influenza B virus | Multiplexed real-time RT-PCR | Qualitative, instrument read | Health care provider-collected nasopharyngeal and nasal swabs and self-collected nasal swabs (collected in a health care setting with instruction by a health care provider) | RdRp gene (ORF1ab) and nucleocapsid gene | LoD: 12 copies/mL | ~ 20 min | |
| Yes | Prescription home testing, health care provider at POC | No | RT-loop mediated isothermal amplification | Qualitative, instrument read | Self-collected nasal swab in people aged ≥14 y and in people aged ≤ 13 y when the specimen is collected by a health care provider at the POC | 2 non overlapping regions of the nucleocapsid gene | LoD: 900 copies/mL | < 30 min | |
| No | Health care provider | No | RT, isothermal amplification | Qualitative, instrument read | Direct nasal, nasopharyngeal or throat swabs | RdRp | LoD: 125 genome equivalents/mL | ≤ 13 min | |
| No | Health care provider | SARS-CoV-2, influenza A and influenza B virus, RSV | Multiplexed real-time RT-PCR | Qualitative, instrument read | Nasopharyngeal or nasal swab | Envelope and N-nucleocapsid (N2) | LoD:131 copies/mL for COVID-19 | 25 min for positive COVID-19 results and 36 min for all 4 pathogens | |
| No | Health care provider | No | RT, isothermal amplification | Qualitative, instrument read | Direct nasal swabs | Nucleocapsid gene | LoD: 1,300 copies/mL | 25 min |
POC: Point-of-care.
As of April 5, 2021. An up-to-date list of POC molecular diagnostic tests is available online at the US Food and Drug Administration’s “In Vitro Diagnostics EUAs: Molecular Diagnostic Tests for SARS-CoV-2.” Those tests that have W in the Authorized Setting column are authorized for POC use. The link for each product’s user instruction is provided in the Authorization Documents section.
Products are listed according to the authorization date.
All of the mentioned products automate all aspects of nucleic acid testing, from nucleic acid extraction to results.
Nasal and nasopharyngeal swabs are contraindicated in people who are susceptible to nosebleeds or have had recent facial or head injury or surgery.
SARS-CoV-2: Severe acute respiratory syndrome coronavirus 2.
OTC: Over-the-counter.
A health care provider includes, but is not limited to, physicians, dentists, nurses, pharmacists, technologists, laboratory directors, epidemiologists, or any other practitioners or allied health care professionals. The Centers for Disease Control and Prevention provides an online guideline for the collecting and handling of clinical specimens for COVID-19 testing.
RT: Reverse transcription.
LoD: Limit of detection.
PPA: Positive percentage agreement.
NPA: Negative percentage agreement.
PCR: Polymerase chain reaction.
NAAT: Nucleic acid amplification test.
RSV: Respiratory syncytial virus.
Available POC∗ antigen diagnostic tests for COVID-19.†
| PRODUCT | TEST AT HOME | ACCESSIBILITY | MULTIANALYTE | METHOD | RESULTS READING | SAMPLE TYPE | TAREGET ANTIGEN | PERFORMANCE EVIDENCE FOR SARS-CoV-2 | TIME TO RESULTS | SUGGESTED TIME POINT FOR TESTING |
|---|---|---|---|---|---|---|---|---|---|---|
| No | Health care provider | Yes | Chromatographic digital immunoassay | Instrument | Direct anterior nasal swab | SARS-CoV-2 nucleocapsid antigen or influenza A and B nucleoprotein | LoD | 20 min | Within the first 6 d of symptom onset | |
| Yes | Prescription home testing, health care provider | No | Lateral flow fluorescence immunoassay | Visual | Direct anterior nares swab | Nucleocapsid protein | LoD: 1.91 x 104 TCID50/mL | 10 min | Within the first 6 d of the onset of symptoms | |
| Yes | Over-the-counter home testing, health care provider | No | Lateral flow fluorescence immunoassay | Instrument | Midturbinate nasal swabs that are self-collected by people aged ≥ 16 y, or are collected by an adult from people aged ≥ 2 yr | Nucleocapsid protein | LoD:103.80 TCID50/mL | 20 min | Intended for use in people with or without symptoms or other reasons to suspect a COVID-19 infection | |
| No | Health care provider | No | Microfluidic immuno-fluorescence assay | Instrument | Direct nasal swab | Nucleocapsid protein | LoD: 32 TCID50/mL | 12 min | Within the first 12 days of symptom onset | |
| No | Health care provider | No | Chromatographic digital immunoassay | Instrument | Nasal swabs | Nucleocapsid protein | LoD: 140 TCID50/mL | 15 min | Within the first 5 d of onset of symptoms | |
| No | Health care provider | No | Lateral flow immunoassay | Visual | Anterior nares swab | Nucleocapsid protein | LoD: 7.57x103 TCID50/mL | 10 min | Within the first 5 d of the onset of symptoms | |
| Yes | Over-the-counter home testing; Healthcare provider | No | Lateral flow immunoassay | Visual | Self-collected observed direct anterior nares swab samples from people aged ≥ 15 y. | Nucleocapsid protein | LoD: 140.6 TCID50/mL | 15 min | Within the first 7 d of symptom onset | |
| No | Health care provider | No | Lateral flow immune-luminescent assay | Instrument | Direct anterior nasal swab | Nucleocapsid protein | LoD: 88 TCID50/mL | 30 min | Within the first 5 d of onset of symptoms | |
| No | Health care provider | No | Lateral flow immunoassay | Visual | Nasopharyngeal swab specimens | Nucleocapsid protein | LoD: 6.4 x 103 TCID50/mL | 10 min | Within the first 5 d of onset of symptoms | |
| No | Health care provider | Yes | Lateral flow fluorescence immunoassay | Instrument | Direct nasopharyngeal and nasal swab | Nucleocapsid protein from SARS-CoV-2, influenza A, and influenza B | LoD: 91.7 x 103 TCID50/mL | 15 min | Within the first 5 d of onset of symptoms | |
| No | Health care provider | No | Lateral flow fluorescence immunoassay | Instrument | Direct nasopharyngeal and nasal swab | Nucleocapsid protein | LoD: 113 TCID50/mL | 15 min | Within the first 5 d of onset of symptoms |
POC: Point-of-care.
As of April 5, 2021. An up-to-date list of POC antigen diagnostic tests is available online at the US Food and Drug Administration’s “In Vitro Diagnostics EUAs: Antigen Diagnostic Tests for SARS-CoV-2.” Those tests that have W in the Authorized Setting column are authorized for POC use. The link for each product’s user instruction is provided in the Authorization Documents section.
Products are listed according to the authorization date.
Nasal and nasopharyngeal swabs are contraindicated in people who are susceptible to nosebleeds or have had recent facial or head injury or surgery.
None of the listed tests differentiate between severe acute respiratory syndrome coronavirus (SARS-CoV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Possible false-positive results in patients with history of infection with SARS-CoV-2.
Failure of the user to follow the test procedure correctly may affect the test performance adversely or invalidate the test result. All results are presumptive in asymptomatic people. Positive results indicate the presence of viral antigens, but the clinical correlation with medical history and other diagnostic information are necessary to determine infection status. Negative results are presumptive in symptomatic people.
A health care provider includes, but is not limited to, physicians, dentists, nurses, pharmacists, technologists, laboratory directors, epidemiologists, or any other practitioners or allied health care professionals. The Centers for Disease Control and Prevention provides an online guideline for the collecting and handling of clinical specimens for COVID-19 testing.
LoD: Limit of detection.
TCID50: Median tissue culture infectious dose.
PPA: Positive percentage agreement.
NPA: Negative percentage agreement.
Available POC∗ serologic tests for COVID-19.†
| PRODUCT | TEST AT HOME | ACCESSIBILITY | METHOD | RESULTS READING | SAMPLE TYPE | TAREGET ANTIBODY | PERFORMANCE EVIDENCE FOR SARS-CoV-2 | TIME TO RESULSTS |
|---|---|---|---|---|---|---|---|---|
| No | Health care provider | Lateral flow | Visual | Fingerstick whole blood | IgM and IgG | IgM NPA | 20 min | |
| No | Health care provider | Lateral flow | Visual | Fingerstick whole blood | IgG | PPA: 90.0% (95% CI, 73.6% to 97.3%) | 15 min | |
| No | Health care provider | Lateral flow | Visual | Fingerstick whole blood | IgM and IgG | Multiple clinical performance data. See the instructions for use. | 10 min | |
| No | Health care provider | Lateral flow | Visual | Fingerstick whole blood | IgM and IgG | IgM PPA: 88.89% (95% CI, 75.95% to 96.29%) | 10 min | |
| No | Health care provider | Lateral flow | Visual | Fingerstick whole blood | IgM and IgGs | IgM NPA: 100% (95% CI. 97.7% to 100%) | 15 min |
POC: Point-of-care.
As of April 5, 2021. An up-to-date list of POC antigen diagnostic tests is available online at the US Food and Drug Administration’s “In Vitro Diagnostics EUAs: Serology and Other Adaptive Immune Response Tests for SARS-CoV-2.” Those tests that have W in the Authorized Setting column are authorized for POC use. The link for each product’s user instruction is provided in the Authorization Documents section.
Products are listed according to the authorization date.
Results from antibody testing should not be used to diagnose or exclude severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or to inform infection status.
For optimal test performance, proper sample collection is critical. Failure to follow the procedure may give inaccurate results. In the early onset of symptom, anti-SARS-Cov-2 immunoglobulin M (IgM) and immunoglobulin G (IgG) antibody concentrations may be below detectable levels. SARS-CoV-2 IgG antibodies may be below detectable levels in patients who have been exhibiting symptoms for less than 15 days. Results from immunosuppressed patients should be interpreted with caution. False-positive results may be due to cross-reactivity with past or present infection with non-SARS-CoV-2 strains, such as coronaviruses HKU1, NL63, OC43, or 229E. Other information should be considered, including clinical history and local disease prevalence, in assessing the need for a second but different serology test to confirm an immune response.
A health care provider includes, but is not limited to, physicians, dentists, nurses, pharmacists, technologists, laboratory directors, epidemiologists, or any other practitioners or allied health care professionals. The Centers for Disease Control and Prevention provides an online guideline for the collecting and handling of clinical specimens for COVID-19 testing.
NPA: Negative percentage agreement.
CI: Confidence interval.
PPA: Positive percentage agreement.
Refer to product catalog for further information.