Rapid tests for COVID-19 (SARS-CoV-2) can have both false positive and false negative results. The causes vary with the analytical method. The chances that a positive result may be a false positive is affected by the prevalence of COVID-19 in the population.
Impact of false-negative test:
(1) release of infectious person into society
(2) inappropriate management
Impact of false-positive test:
(1) unnecessary isolation with economic impact
(2) psychological stress
(3) failure to recognize condition causing the false-positive
(4) unnecessary investigation
(5) unnecessary treatment
Causes of a false-positive antigen test include:
(1) acute HIV
(2) cross reaction with other coronaviruses
(3) specimen error
(4) testing and reporting errors, including result misinterpretation
Causes of a false-positive antibody test include:
(1) active autoimmune disorder (rheumatoid arthritis, SLE, granulomatosis with polyangiitis, etc)
(2) cold agglutinin (hepatitis C, Mycoplasma, etc)
(3) specimen error
(4) testing and reporting errors, including result misinterpretation
Causes of a false-positive PCR test include:
(1) environmental contamination at the time of collection
(2) contamination of reagents
(3) cross reaction with other coronaviruses
(4) sample collection errors
(5) testing and reporting errors, including result misinterpretation
