Medical researchers in Hong Kong reported Monday that a recovered Covid-19 patient has the disease again, just 4 ½ months after the first episode.
That may come as a shock to many Americans who thought they were safe.
Despite cautions from experts, it’s been widely assumed that a person who contracts Covid-19 and recovers would be immune to reinfection by the coronavirus, at least for an extended period of time, if not permanently.
But this kind of “herd immunity” doesn’t seem to hold, at least in some cases.
“The report is of concern because it suggests that immunity to the coronavirus may last only a few months in some people. And it has implications for vaccines being developed for the virus,” reports the New York Times.
It raises new concerns about just how effective any vaccine might be.
The patient is described as a previously healthy 33-year-old man who was “cleared of Covid-19 and discharged from a hospital in April, but tested positive again after returning from Spain via Britain on Aug. 15,” Reuters says. It’s the first confirmed case of reinfection in the world, although others have been reported.
The discovery required aggressive testing, since the patient had only mild symptoms the first time around and none the second.
“He was found to have contracted a different coronavirus strain from the one he had previously contracted and remained asymptomatic for the second infection.”
“The finding does not mean taking vaccines will be useless,” Dr. Kai-Wang To, a leading author of the report told the news agency. “Immunity induced by vaccination can be different from those induced by natural infection,” To said. “[We] will need to wait for the results of the vaccine trials to see if how effective vaccines are.”
The Times notes that the group of coronaviruses responsible for the common cold “are known to cause reinfections in less than a year, but experts had hoped that the new coronavirus might behave more like its cousins SARS and MERS, which seemed to produce longer-lasting immunity of a few years.”
