TESTING

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Reliable and affordable tests are urgently needed to control the pandemic

Our SPECIAL PROJECT is helping to make screening tests available around the world.

COVID-19 TESTING

TERMINOLOGY 

  • Novel Coronavirus (2019-nCoV) was the initial name of the virus.

  • Severe Acute Respiratory Syndrome Coronavirus (SARS-Cov-2) is new name of the virus based on its similarity to the SARS of 2002-2003.

  • Coronavirus 2019 (COVID-19) is the name for the actual disease.

  • Incubation period is the time between infection and symptoms, considered to be 4-14 days.

POINT OF CARE (PoC) & SELF-TESTING 

  • Point of Care (PoC) means the the sample is collected at a hospital, clinic, doctor's office, pharmacy etc. The analysis itself is done in a laboratory or in a special machine at PoC.

  • Self -Testing applies mainly to antibody rapid tests, where the person pricks their finger to retrieve a small amount of blood and perform the test on their own, with the result visible on a stripsimilar to a pregnancy test. 

TYPES OF TESTS

 

  • PCR (polymerase chain reaction) test;

  • Antigen test;

  • Antibody test.

Different tests are need as biological markers change over time.

Source: The. Native Antigen Company & IFF 2020 

There is on-going debate how long-lasting immunity really is.  Some say that antibody formation does not guarantee long-term immunity to the virus and that a renewed exposure can create an acute infection. This is being studied but more time is required to observe flaming up of an acute infection in patients with antibodies. All this does not mean that antibody tests should be stopped. Of course, they should and will become more reliable, improved etc. but they are the only way to understand herd immunity.

PCR TEST 

  • A swab is taken from the mouth or nose (one saliva test is certified) and then sent to a certified laboratory for analysis or used in a rapid testing machine at PoC.

  • A technique called Polymerase Chain Reaction (PCR) is used to detect the presence of the SARS CoV-2 virus on a relative of the DNA, the ribonucleic acid (RNA); hence it is sometimes referred to as a nucleic acid test.

  • The importance of PCR tests is that they can detect the virus during the acute stage of the infection as the viral RNA is formed much before antibodies.

  • The challenge with PCR tests is that they require laboratories or expensive testing machines, steady supplies of swabs and other materials, trained technicians, logistics, etc. All these factors contribute to bottlenecks and waiting periods even tough the latest machines can deliver results in as little as 15 minutes. 

  • A false negative can occur up to 30% of the time and therefore patients should be tested several times before an all-clear is given. 

PCR testing requires costly infrastructure but shows infection early.

ANTIGEN TEST

  • A swab sample, same way as for PCR tests, is taken and inserted into a special machines.

  • The machine contains certain biological compounds as reagents to directly detect the SARS-CoV-2 antigen, a molecule or molecular structure present on the outside of the virus.

  • Same as PCR, this test can determine an infection early on, i.e. during the acute stage. 

  • Bosch has an antigen test that runs on its Vivalytic system (depicted), consisting of an analyser device and matching test cartridges with compounds to detect the SARS-CoV-2 and nine other respiratory viruses. This allows healthcare professionals to determine right a way whether the person is infected with SARS-CoV-2 or has another respiratory infect, thereby eliminating the need for further tests. 

Antigen tests are similar to PCR but some provide innovative features.

ANTIBODY TEST

  • A blood sample by prick of the finger is taken and dropped onto a strip in a plastic cassette. 

  • The cassette contains a strip with antigens from SARS-CoV-2 conjugated to gold nanoparticles.

  • A technique called lateral flow immunoassay is used to bind the antibodies (immunoglobulin) IgM and IgG to the antigen and the gold, making the result visible as a line, similar to a pregnancy test. 

  • Positive IgM & IgG means that that the person was infected recently.  If the IgG is positive but the IgM is low or negative, then it is likely that the person had an infection in the past (and is now immune).

  • The advantage of these tests is they are inexpensive and do not require a laboratory.

  • Limitation is that antibodies form 5-14 days after an infection and the person might infected others and have immunity; hence this most useful for screening the population to understand herd immunity.

  • In terms of accuracy, FDA-approved antibody tests show more than 90% sensitivity and 95% specificity. 

Antibody tests are inexpensive but show infection later - useful for screening.

TESTS APPROVED BY THE FDA

 

The U.S. FDA approves on an on-going basis both molecular and antibody tests under the "Emergency Use Authorization" (EUA)The complete list of both approved molecular and antibody tests can be found here.

TESTS IN THE EU 

Directive 98/79/EC7 on in-vitro diagnostic medical devices applies to COVID-19 tests. The tests must be CE-certified with a "Declaration of Conformity", which includes GNP, ISO, Biosafety, etc. Clinical studies are also recommended but the EU permits member states to use tests for which a Declaration of Conformity has not been obtained as yet. The Directive can be found here.

ANTIBODY TESTS FROM CHINA 

Like everything else, many antibody tests are manufactured in China and offered at competitive prices. For imports into the EU these products must be CE-certified (see Antibody Tests in the EU). Over the last weeks, several million of tests turned out to be fake or sub-standard. To address this problem, China amended the export policy, requiring a special license from the Ministry of Commerce and a declaration from the destination that it accepts the product standards. Currently, there are some 25 companies licensed to export tests while hundreds were effectively shut down.  All these factors have created immense pressure on supply.

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