Dead fragments of novel coronavirus led to false positives in recovered patients
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This addresses the concern of reinfection or reactivation in people who have recovered from COVID-19
- South Korea announced that patients who were declared as COVID-19 recovered have once again tested positive, suggesting that it could be a case of reinfection or reactivation (where the virus is not completely cleared once again begins to replicate).
- By the end of April, South Korea had recorded 263 such cases, China too reported such cases.
Cause of concern
- This news caused concern as it highlighted the issue of low levels of immunity in people who have recovered and the short duration of protection offered by antibodies developed in response to the infection.
- If natural infection shows only a short duration of protection, it raised concerns about the duration of protection that vaccines can offer.
- But on April 30, South Korea confirmed that dead virus fragments still present in recovered people had led the people numbering over 260 to test positive again for the novel coronavirus even weeks after marking full recovery.
- The RT-PCR used for testing samples amplifies the genetic material of the virus prior to testing.
- The molecular test cannot distinguish between dead and live genetic fragments and hence cannot make out whether the virus is alive or not.
- There is no indication that patients who retest positive are contagious, even though about 44% of them showed mild symptoms.