Photographer: AFP via Getty Images
Photographer: AFP via Getty Images
Two patients in China who recovered from Covid 19 months ago tested positive for the coronavirus again, and worried about the virus’ ability to sit and reappear in people who had previously infected it.
A 68-year-old woman in the central Chinese province of Hubei, where the new coronavirus first appeared in December, tested positive on Sunday, six months after she was diagnosed with Covid-19 and recovered. Another man revealed that he contracted the disease in April after returning from abroad on Monday tested positive in Shanghai, but showed no symptoms.
None of the patients’ close contacts has tested positive for the virus, but they have been quarantined, local authorities said.
The two cases are the latest addition to a growing number “antilechanal virus ”anecdotes found among patients who believe they have recovered from the viral infection, which has sickened more than 20 million worldwide and killed 748,000. Although it is rare for recovering patients to test positive again, the phenomenon raises questions about why some patients suffer from long-term symptoms, and whether any immunity to the disease is too effective to protect against re-infection.
Some studies have shown the level of protective antibodies that an infected person can build up to fight the virus rap sag after only a few months, possibly making them a second time susceptible to the same pathogen. However, so far there is not much evidence that re-infection has taken place in this pandemic.
Some experts have raised the possibility that others cells continue to provide immunity even after antibodies disappear. Researchers in South Korea have suggested that the virus recovered in patients months after recovery may be the remains of dead virus particles that are no longer infected.
– With the help of Sharon Chen, and Dong Lyu
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