European patients reinfected with coronavirus

A patient in the Netherlands and another in Belgium have been reinfected with the coronavirus, Dutch media reported Tuesday, following reports that scientists in Hong Kong had confirmed the first known reinfection.

The Dutch patient was an older person with a weakened immune system, Dutch broadcaster NOS reported, citing virologist Marion Koopmans. 

Koopmans said it was more common for people to remain infected with the virus for a long time, but with mild symptoms, before it suddenly flares up again. A reinfection — as is the case with the Dutch and Belgian cases — requires genetic testing in both the first and second instances of infection to see whether there are differences in the virus present, Koopmans said.

"That someone would pop up with a reinfection, it doesn't make me nervous," she said. "We have to see whether it happens often."

Belgian case 'not good news'

The Belgian patient displayed only mild symptoms, NOS reported, citing virologist Marc Van Ranst. "It's not good news," Ranst said. 

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The development shows that the antibodies the patient developed in the first case were not strong enough to fend off an infection from a slightly different variant of the virus, he said.

It is not clear if this is a rare phenomenon or if there are "many more people who could have a reinfection after six or seven months," he said.

First reinfection confirmed in Hong Kong

The European developments follow Monday reports of the first confirmed coronavirus reinfection, a man in Hong Kong.

The 33-year-old, who was infected with the virus in March, returned in mid-August from a trip to Spain infected with a different strain. 

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"COVID-19 patients should not assume after they recover that they won't get infected again," said elvin Kai-Wang To, a microbiologist at the University of Hong Kong.

"It shows that some people do not have lifelong immunity" to the virus even if they've already been infected, To said.

Some experts see the news as a positive development. "If there is a reinfection, it suggests the possibility there was residual immunity ... that helped protect the patient'' from getting sick again, said Jesse Goodman, a former US Food and Drug Administration chief scientist, now at Georgetown University, responding to the Hong Kong case.

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The Hong Kong patient did not display any symptoms during his most recent infection. 

Implications for vaccine development

The possibility of reinfection has implications for the global race to develop a vaccine and for key decisions on when people return to school and work.

Speaking on the Hong Kong case, London School of Hygiene and Tropical Medicine microbiologist Brendan Wren said the case was "a very rare example of reinfection and it should not negate the global drive to develop COVID-19 vaccines."

kp/rc (AFP, AP, Reuters)