Provincial health workers perform coronavirus disease (COVID-19) nasal swab tests on Raymond Robins of the remote First Nation community of Gull Bay, Ontario, Canada April 27, 2020. (Reuters/David Jackson)
PHILIPSBURG--The Ministry of Public Health, Social Development and Labour VSA Inspectorate, in an effort to share information about SARS-CoV-2 in COVID-19 tests and testing methodology, released details on Tuesday explaining the process that is being used locally.
“In the ongoing pandemic of COVID-19 it is important to know who is infected or was infected with the causing SARS-CoV-2 virus. By doing so, adequate treatment can be provided; preventive measures can be taken; epidemiological surveillance and research in a community can be conducted and protocols and policies can be developed or measures can be loosened up,” said the inspectorate in a press release on Tuesday.
The inspectorate said, “In light of the hype surrounding testing in COVID-19 and everyone suddenly becoming an expert in the area of testing, before having and sharing an opinion one should have a proper understanding of the disease; the type of tests and the concepts of sensitivity; specificity and validation of tests and interpretation of a test result in relation to the clinical manifestation.”
According to the release, the sensitivity of a test is the ability to detect the intended substance in the human body i.e. antibodies. If the sensitivity is lower than 100 per cent, false-negative results will occur.
Specificity of a test is the ability to be unique in such a way that it provides a negative result in someone who has not been infected. If the specificity is lower than 100 per cent, false-positive results will occur.
Validation of a test establishes whether it can be applied for the purpose it is meant for with achievement of near 100 per cent sensitivity and near 100 per cent specificity; the margin of error must be known and understood in the interpretation of test results.
According to the release, before a test can be made available and applied, it has to be validated and certified by the US Food and Drug Administration (FDA) or obtain the European CE Marking.
“Certification indicates conformity with US or European health, safety and environmental protection standards,” said the inspectorate. “A certified product can be commercialised within the territory of the United States of America (USA) respectively, the European Economic Area and must be accompanied by technical documents on the product and its use.”
Under section 564 of the US Federal Food, Drug and Cosmetic Act, the FDA Commissioner may allow unapproved medical products or unapproved uses of approved medical products to be used in an emergency to diagnose, treat or prevent serious or life-threatening diseases or conditions caused by CBRN (chemical, biological, radiological and nuclear) threat agents when there are no adequate, approved and available alternatives. This is a so-called FDA emergency use authorisation (EUA) certificate, said the release.
An FDA EUA certificate will always contain terms which caution potential users of the product on the limitations of the product.
The molecular and serological immune assay are the tests currently available.
Molecular tests i.e. reverse transcriptase-polymerase chain reaction (RT-PCR) tests quantify transcript ribonucleic acid (RNA) levels in cells and tissues. Transcription is the first of several steps of DNA-based gene expression in which a particular segment of DNA is copied into RNA.
The COVID-19 real time RT-PCR (rRT-PCR) test is a real-time test for the approximate detection of SARS-CoV-2 nucleic acid (genetic material) in upper and lower respiratory specimens collected from individuals suspected of COVID-19 by their healthcare provider. Clinical correlation with patient history and other diagnostic information is necessary to determine patient infection status.
A positive test result for COVID-19 indicates that RNA from SARS-CoV-2 was detected and the patient is presumptively infected with the virus and contagious.
The approved rRT-PCR tests are currently the most reliable tests available to detect an infection with the SARS-CoV-2 virus, especially in the early stages of an infection. Swabs must be taken properly to avoid false-negative test results. They are used as the primary diagnostic test for SARS-CoV-2 infection.
Serological immune assay tests detect (viral-bacterial) specific antibodies in a disease and are meant to establish whether a person has been recently infected, infected in the past or if a person is immune. Rapid and many point-of-care (POC) tests belong in the category of serological tests.
Antibodies against a viral or bacteriological agent are developed typically one to two weeks after someone has become sick, while RNA is detectable at an earlier stage.
The inspectorate said in the case of SARS-CoV-2, many of the serological tests for antibodies still lack the required specificity and sensitivity, potentially leading to false- negative or false-positive test results. “Due to these limitations, serological tests have not been validated as yet for individual diagnostic testing for SARS-CoV-2 by the Centers for Disease Control and Prevention CDC and the FDA in the USA, in Europe and not by the Netherlands National Institute for Public Health and the Environment RIVM up until today. This might change in the near future as many serological tests are currently being evaluated,” said the inspectorate.
“For now, the use of tests for antibodies are limited to being an additional test to the rRT-PCR tests to establish whether a person had an immune response to SARS-CoV-2, whether symptoms developed from infection or the infection was asymptomatic,” the department added.
Some of these tests have been designed and validated for broad-based surveillance and research that will provide information needed to guide the response to the pandemic and protect the public’s health. The results of these studies will allow the authorities to estimate how many people have been infected nationally. The results will also provide information about the percentage of residents who have not had COVID-19 and are still at risk for infection.
The inspectorate added that there are currently many non-certified and fake serological tests being sold.
