BEIJING (BLOOMBERG) – Two patients in China who recovered from Covid-19 months ago tested positive for the coronavirus again, raising concern of the virus’s ability to linger and reactivate in people who it previously infected.
A 68-year-old woman in the central Chinese province of Hubei, where the novel coronavirus first surfaced in December, tested positive on Sunday (Aug 9), six months after she was diagnosed with Covid-19 and recovered.
Another man found to have contracted the disease in April after returning from abroad tested positive in Shanghai on Monday but hasn’t shown any symptoms.
None of the patients’ close contacts has tested positive for the virus, but they have been placed under quarantine, local authorities said.
The two cases are the latest addition to a growing number of “virus reactivation” anecdotes found among patients believed to have recovered from the viral infection, which has sickened more than 20 million worldwide and killed 748,000.
While it is rare for recovered patients to test positive again, the phenomenon raises questions over why some patients suffer from long-term symptoms, and whether any immunity to the disease might be too ephemeral to protect against re-infection.
Some studies have shown the level of protective antibodies an infected person may build up to fight the virus quickly drop after only a few months, possibly making them susceptible to the same pathogen a second time.
Related Story No known case here of Covid-19 reinfection, but ministry on lookout Related Story Long-term effects of Covid-19 infection being studied in Singapore However, there is little evidence so far that re-infection has been occurring in this pandemic.
Some experts have raised the possibility that other cells continue to provide immunity even after antibodies fade.
Researchers in South Korea have suggested that the virus detected in patients months after recovery could be the vestiges of dead virus particles that are no longer infectious.
Related Stories: Related Story 42 new Covid-19 cases in Singapore, including 1 in the community and 11 imported Related Story Global coronavirus cases hit 20 million Related Story Early-stage coronavirus vaccine trial begins in Singapore Related Story Why the coronavirus is more likely to ‘superspread’ than the flu Related Story Long and hard battle to clear worker dorms of Covid-19 Related Story Hong Kong to offer free Covid-19 tests to all residents Related Story Vietnam PM says risk of widespread Covid-19 infection ‘very high’ Related Story Electronic wristband to ensure SHN: Quarantine monitoring devices being used by others worldwide Related Story What Covid-19 lockdown 2.0 looks like in Australia and elsewhere: Harsher rules, deeper confusion Related Story When it comes to Covid-19 vaccines, rich nations are first in line Read the latest on the Covid-19 situation in Singapore and beyond on our dedicated site here .
Get The Straits Times app and receive breaking news alerts and more. Download from the Apple App Store or Google Play Store now.
LINK ORIGINAL: TheStraitsTimes