Socio-Economics History Blog

Socio-Economics History Blog

HALF of Positive Coronavirus Antibody Tests Could Be Wrong & Give False Sense of Security – Top US Health Agency

by mosesman
FILE PHOTO: A man looks at a vial of his blood drawn at a New York facility testing for antibodies to the coronavirus. © Reuters / Mike Segar
  • HALF of Positive Coronavirus Antibody Tests Could Be Wrong & Give False Sense of Security – Top US Health Agency
    by https://www.rt.com/
    Antibody tests used to confirm whether someone has ever had the coronavirus could be wrong half of the time, driving bad policy decisions, the US Centers for Disease Control and Prevention warns.
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    The Centers for Disease Control and Prevention (CDC), a top federal health agency, said in a new guidance on Tuesday that during mass screenings in various populations, up to half of the positive results from antibody tests – also known as serologic tests – could be false, warning there are still major obstacles in determining who has been infected or what immunity they might have.
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    The unreliable tests shouldn’t inform decisions about moving potential patients to “congregate settings” – such as schools, dormitories or jails – nor choices “about returning persons to the workplace,” the CDC said.
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    But even when a patient is “truly positive” for antibodies, the agency said the result still doesn’t prove that the individual is “protected from future infection” or immune to the virus.
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    “Serologic testing should not be used to determine immune status in individuals until the presence, durability, and duration of immunity is established.”
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    The rate of false positive and negative test results heavily depends on the overall number of infections in a population. If a relatively low proportion of people in a given area have contracted the virus – five percent, for example – the CDC says even a highly sensitive and specific test will still yield a significant number of false positives, up to 51 percent.
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    “In other words, less than half of those testing positive will truly have antibodies.”
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    Echoing the new guidance, a research team at the University of Minnesota has also warned about antibody tests, issuing a report last week cautioning that they should not be used as a “diagnostic tool” given their inaccuracy.
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