Viral disease testing

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Viral disease testing is the use of a variety of testing techniques for a variety of purposes, including diagnosing conditions, assessing immunity and understanding disease prevalence. The primary approaches include DNA/RNA tests, serological tests and antigen tests.

Contents

History

COVID-19

In March 2020, Abbott received emergency use authorization (EUA) for its isothermal nucleic acid test for COVID-19. It produces test results in 5 minutes using its ID NOW portable testing system. [1] It also received EUA for its m2000-based laboratory nucleic acid test for COVID-19. [2]

In April 2020, Abbott received EUA for its ARCHITECT IgG laboratory antibody test for COVID-19. [3] Also in April, Abbott's ID NOW test was reported to have sensitivity of 85.2%. [4] A later study found sensitivity of only 52%, inducing the FDA to issue an alert. [5] A different study found sensitivity of 91%. [6] The UK spent $20 million for antibody tests that proved flawed. [7]

In May 2020, a rapid antigen test from Quidel Corporation received EUA for detecting SARS-CoV-2. [8] Test results were said to be available at point of care within 15 minutes. [9] Sensitivity is 85%. [1] Also in May 2020, a CRISPR genetic test was approved for emergency use that claimed 100% selectivity and 97.5% sensitivity. [10] That month Abbott received EUA for its Alinity antibody test for COVID-19. The company claimed 100% sensitivity and 99.6% specificity for patients tested 14 days after symptoms began. [10] Another review found that the accuracy of PCR tests depended on the interval between the infection and the test. Immediately after infection, the sensitivity was 0, rising to 80% after three days and then declining thereafter. [11]

In May 2020 the FDA withdrew approval for 29 of 41 antibody tests for which it had given EUAs. [12]

Types

DNA/RNA tests

Tests for viral DNA can look for either DNA or RNA. They typically use reverse transcriptase polymerase chain reactions to multiply the amount of genetic material in a small sample into an amount that is measurable. The genetic material is generally taken from the nose/sinus. One study found clinical sensitivity was found to range from 66 to 80%. [13] Another found accuracy of 70%. [14]

A newer form uses CRISPR to produce a test result without requiring lab equipment. The test reacts with genetic material to produce a visible signal without requiring amplification. [10]

Serological tests

Serological tests look for the presence of antibodies in a test sample. Antibodies are materials that the body produces to fight off an infection. The primary antibodies sought in viral testing are IgE and IgG.[ citation needed ]

Rapid antigen tests

A rapid antigen test quickly searches for antigens, protein fragments that are found on the surface of or within a virus. Antigen tests can be analyzed within a few minutes. Antigen tests are less accurate than PCR tests. It has a low false positive rate, but a higher false negative rate. A negative test result may require confirmation with a PCR test. [8] Advocates claim that antigen tests are less expensive and can be scaled up more rapidly than PCR tests. [8] Antigen tests are available for a variety of conditions, including streptococcus, [15] influenza, giardia, [16] Ebola and Helicobacter pylori . [17] Antigens can be detected via blood, urine or stool.[ citation needed ]

Imaging

Imaging such as computerized tomography can be used to inform a diagnostic process. CT scans are considerably more expensive than nucleic acid tests and involve a small dose of radiation. For COVID-19, they are seen as the most accurate diagnostic tool, because the disease creates patchy "ground glass" areas in the lungs that are revealed by a scan. One study found 97% sensitivity. [14]

Accuracy

Accuracy is measured in terms of specificity and selectivity. Test errors can come false positives (the test is positive, but the virus is not present) or false negatives (the test is negative, but the virus is present). [13]

Sensitivity

Sensitivity indicates whether the test accurately identifies whether the virus is or is present. A 90% sensitive test will correctly identify 90% of infections, leaving 10% with a false negative result. [13]

Specificity

Specificity indicates how well-targeted the test is to the virus in question. Highly specific tests pick up only the virus in question. Non-selective tests pick up other viruses as well. A 90% specific test will correctly identify 90% of those who are uninfected, leaving 10% with a false positive result. [13]

See also

Related Research Articles

<span class="mw-page-title-main">Diagnosis of HIV/AIDS</span> Immunological test

HIV tests are used to detect the presence of the human immunodeficiency virus (HIV), the virus that causes acquired immunodeficiency syndrome (AIDS), in serum, saliva, or urine. Such tests may detect antibodies, antigens, or RNA.

<span class="mw-page-title-main">Respiratory syncytial virus</span> Species of a virus

Respiratory syncytial virus (RSV), also called human respiratory syncytial virus (hRSV) and human orthopneumovirus, is a contagious virus that causes infections of the respiratory tract. It is a negative-sense, single-stranded RNA virus. Its name is derived from the large cells known as syncytia that form when infected cells fuse.

Abbott Laboratories is an American multinational medical devices and health care company with headquarters in Abbott Park, Illinois, United States. The company was founded by Chicago physician Wallace Calvin Abbott in 1888 to formulate known drugs; today, it sells medical devices, diagnostics, branded generic medicines and nutritional products. It split off its research-based pharmaceuticals business into AbbVie in 2013.

<span class="mw-page-title-main">Seroconversion</span> Development of specific antibodies in the blood serum as a result of infection or immunization

In immunology, seroconversion is the development of specific antibodies in the blood serum as a result of infection or immunization, including vaccination. During infection or immunization, antigens enter the blood, and the immune system begins to produce antibodies in response. Before seroconversion, the antigen itself may or may not be detectable, but the antibody is absent. During seroconversion, the antibody is present but not yet detectable. After seroconversion, the antibody is detectable by standard techniques and remains detectable unless the individual seroreverts, in a phenomenon called seroreversion, or loss of antibody detectability, which can occur due to weakening of the immune system or decreasing antibody concentrations over time. Seroconversion refers the production of specific antibodies against specific antigens, meaning that a single infection could cause multiple waves of seroconversion against different antigens. Similarly, a single antigen could cause multiple waves of seroconversion with different classes of antibodies. For example, most antigens prompt seroconversion for the IgM class of antibodies first, and subsequently the IgG class.

Heterophile antibodies are antibodies induced by external antigens.

An Emergency Use Authorization (EUA) in the United States is an authorization granted to the Food and Drug Administration (FDA) under sections of the Federal Food, Drug, and Cosmetic Act as added to and amended by various Acts of Congress, including by the Pandemic and All-Hazards Preparedness Reauthorization Act of 2013 (PAHPRA), as codified by 21 U.S.C. § 360bbb-3, to allow the use of a drug prior to approval. It does not constitute approval of the drug in the full statutory meaning of the term, but instead authorizes the FDA to facilitate availability of an unapproved product, or an unapproved use of an approved product, during a declared state of emergency from one of several agencies or of a "material threat" by the Secretary of Homeland Security.

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QuidelOrtho Corporation is a major American manufacturer of diagnostic healthcare products that are sold worldwide.

<span class="mw-page-title-main">Cepheid (company)</span> American molecular diagnostics company

Cepheid is an American molecular diagnostics company that is a wholly owned subsidiary of Danaher Corporation. Its systems automate traditional nucleic acid tests. The tests can be used to identify and analyze pathogens and genetic disorders. Cepheid sells clinical tests for healthcare-associated infections, infectious diseases, sexual health, oncology and genetics.

<span class="mw-page-title-main">Rapid antigen test</span> Fast medical lateral flow test

A rapid antigen test (RAT), sometimes called a rapid antigen detection test (RADT), antigen rapid test (ART), or loosely just a rapid test, is a rapid diagnostic test suitable for point-of-care testing that directly detects the presence or absence of an antigen. RATs are a type of lateral flow test detecting antigens, rather than antibodies or nucleic acid. Rapid tests generally give a result in 5 to 30 minutes, require minimal training or infrastructure, and have significant cost advantages. Rapid antigen tests for the detection of SARS-CoV-2, the virus that causes COVID-19, have been commonly used during the COVID-19 pandemic.

Viral load monitoring for HIV is the regular measurement of the viral load of individual HIV-positive people as part of their personal plan for treatment of HIV/AIDS. A count of the viral load is routine before the start of HIV treatment.

<span class="mw-page-title-main">COVID-19 testing</span> Diagnostic testing for SARS-CoV-2 virus infection

COVID-19 testing involves analyzing samples to assess the current or past presence of SARS-CoV-2. The two main types of tests detect either the presence of the virus or antibodies produced in response to infection. Molecular tests for viral presence through its molecular components are used to diagnose individual cases and to allow public health authorities to trace and contain outbreaks. Antibody tests instead show whether someone once had the disease. They are less useful for diagnosing current infections because antibodies may not develop for weeks after infection. It is used to assess disease prevalence, which aids the estimation of the infection fatality rate.

<span class="mw-page-title-main">Casirivimab/imdevimab</span> Antiviral combination medication

Casirivimab/imdevimab, sold under the brand name REGEN‑COV among others, is a combination medicine used for the treatment and prevention of COVID‑19. It consists of two human monoclonal antibodies, casirivimab and imdevimab that must be mixed together and administered as an infusion or subcutaneous injection. The combination of two antibodies is intended to prevent mutational escape. It is also available as a co-formulated product. It was developed by the American biotechnology company Regeneron Pharmaceuticals.

The AbC-19 rapid antibody test is an immunological test for COVID-19 exposure developed by the UK Rapid Test Consortium and manufactured by Abingdon Health. It uses a lateral flow test to determine whether a person has IgG antibodies to the SARS-CoV-2 virus that causes COVID-19. The test uses a single drop of blood obtained from a finger prick and yields results in 20 minutes. The sensitivity of this test is 98.03% while the specificity is 99.56%. This test is paired with an easy-to-use mobile app which allows a trained professional to generate an antibody test certificate for storing on a person's smartphone.

Bamlanivimab is a monoclonal antibody developed by AbCellera Biologics and Eli Lilly as a treatment for COVID-19. The medication was granted an emergency use authorization (EUA) by the US Food and Drug Administration (FDA) in November 2020, and the EUA was revoked in April 2021.

Bamlanivimab/etesevimab is a combination of two monoclonal antibodies, bamlanivimab and etesevimab, administered together via intravenous infusion as a treatment for COVID-19. Both types of antibody target the surface spike protein of SARS‑CoV‑2.

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<span class="mw-page-title-main">COVID-19 rapid antigen test</span> Diagnostic test for a SARS-CoV-2 infection

COVID-19 rapid antigen tests or RATs, also frequently called COVID-19 lateral flow tests or LFTs, are rapid antigen tests used to detect SARS-CoV-2 infection (COVID-19). They are quick to implement with minimal training, cost a fraction of other forms of COVID-19 testing, and give users a result within 5–30 minutes. RATs have been used in several countries as part of mass testing or population-wide screening approaches. Many RATs can be used for self-testing, in which an individual "collects their own specimen… and interpret[s] their test result themselves".

Seegene, Inc is a Korean manufacturer of in vitro diagnostic (IVD) products, particularly molecular diagnostics. Its portfolio includes a range of assays and screening products for sepsis, respiratory diseases such as influenza and respiratory syncytial virus, as well as sexually transmitted infections (STIs). It was founded in 2000. In early 2020, it began developing and distributing a range of tests for SARS-CoV-2, the virus that causes COVID-19.

References

  1. 1 2 "An Update on Abbott's Work on COVID-19 Testing". www.abbott.com. Retrieved 2020-05-15.
  2. ↑ "Abbott Launches Novel Coronavirus Test". www.abbott.com. Retrieved 2020-05-15.
  3. ↑ "Abbott Launches COVID-19 Antibody Test". www.abbott.com. Retrieved 2020-05-15.
  4. ↑ "Study Raises Questions About False Negatives From Quick COVID-19 Test". NPR.org. Retrieved 2020-05-15.
  5. ↑ Neel, Joe; Hagemann, Hannah (14 May 2020). "FDA Cautions About Accuracy Of Widely Used Abbott Coronavirus Test". NPR.org. Retrieved 2020-05-15.
  6. ↑ Feuer, William (2020-05-13). "Abbott's rapid coronavirus test misses positive cases, raising questions, NYU study finds". CNBC. Retrieved 2020-05-15.
  7. ↑ Kirkpatrick, David D.; Bradley, Jane (2020-04-16). "U.K. Paid $20 Million for New Coronavirus Tests. They Didn't Work". The New York Times. ISSN   0362-4331 . Retrieved 2020-05-31.
  8. 1 2 3 Kim, Sunny (2020-05-09). "FDA gives emergency authorization for new antigen test to help detect coronavirus quicker and cheaper". CNBC. Retrieved 2020-05-10.
  9. ↑ "FDA approves new coronavirus antigen test with fast results". www.cbsnews.com. May 9, 2020. Retrieved 2020-05-11.
  10. 1 2 3 "CRISPR-based Covid-19 test could be a simple, cheap diagnostic". STAT. 2020-05-05. Retrieved 2020-05-11.
  11. ↑ "False negatives raise more questions about coronavirus test accuracy". Honolulu Star-Advertiser. 2020-05-14. Retrieved 2020-05-15.
  12. ↑ "Coronavirus (COVID-19) Update: FDA Provides Promised Transparency for Antibody Tests". FDA. 2020-05-26. Retrieved 2020-05-31.
  13. 1 2 3 4 Ferran, Maureen (May 7, 2020). "COVID-19 tests are far from perfect, but accuracy isn't the biggest problem". Popular Science. Retrieved 2020-05-10.
  14. 1 2 "CT scans might offer a more accurate way to diagnose Covid-19". STAT. 2020-04-16. Retrieved 2020-05-31.
  15. ↑ Stewart, Emily H.; Davis, Brian; Clemans-Taylor, B. Lee; Littenberg, Benjamin; Estrada, Carlos A.; Centor, Robert M. (2014-11-04). "Rapid Antigen Group A Streptococcus Test to Diagnose Pharyngitis: A Systematic Review and Meta-Analysis". PLOS ONE. 9 (11): e111727. Bibcode:2014PLoSO...9k1727S. doi: 10.1371/journal.pone.0111727 . ISSN   1932-6203. PMC   4219770 . PMID   25369170.
  16. ↑ "Antigen Tests for Giardiasis | Michigan Medicine". www.uofmhealth.org. Retrieved 2020-05-10.
  17. ↑ Gisbert, Javier P.; Pajares, José María (August 2004). "Stool antigen test for the diagnosis of Helicobacter pylori infection: a systematic review". Helicobacter. 9 (4): 347–368. doi:10.1111/j.1083-4389.2004.00235.x. ISSN   1083-4389. PMID   15270750. S2CID   27845752.
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