Posted on Apr 03, 2020, 2 p.m.
According to a letter of authorization the FDA has approved the first antibody test in America designed to detect COVID-19; antibody tests can help to identify those who have already had the virus.
Testing thus far has been designed to find fragments of the virus itself, this type of test uses PCR methods to find viral RNA in nasal samples and is useful for detecting those who are currently infected with the virus.
Current diagnostic tests aren’t helpful in identifying those who have recovered from the virus as they will no longer have detectable levels of viral RNA in their body, but recovered patients may have circulating antibodies in their blood. Widespread antibody testing may be useful for determining how many people were infected with the virus but are no longer and may have developed antibodies to help their immunity.
This new test was produced by the biotech Cellex under the emergency use authorization which allows for such testing to be used prior to gaining full approval, provided there are not any previously approved alternatives.
This test requires a blood sample which will be analyzed only in authorized labs, and it takes 15-20 minutes to provide results. It looks for immunoglobulin M and G antibodies; M is the first antibody that the body makes in response to a foreign substance and can appear for a few days after infection. G is produced in large quantities later in the infection process and is specific to COVID-19; positive results from this test could mean that the person is either infected or was recently infected according to the authorization letter.
Other companies were already making and distributing antibody tests without authorization, but those results could not be used to diagnose a past case of infection according to some reports. According to a report in Live Science other countries such as China have been conducting antibody tests for awhile. Blood tests and other tests looking for viral RNA if taken too early might miss cases according to that report.
Though such testing may be useful to determine whether a person has been infected and has developed antibodies, it is still not clear if those who have recovered gain immunity and how long they will remain immune, as some reports suggest that you can become infected more than once. More research is needed to determine immunity of those who have recovered.
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