Though far from common, some patients developed worse symptoms the second time they became infected with Covid-19.
A medical worker collects a swab sample from a staff member inside a classroom for in Srinagar, India. Photograph: Tauseef Mustafa/AFP/Getty Images
On 15 August, a 33-year-old man landed in Hong Kong after flying home from Spain. On arrival, he was screened for coronavirus. Despite feeling well he tested positive. It was the second time he had picked up Covid-19 in less than five months.
The case immediately caught scientists’ attention. The man was the first in the world to have a confirmed coronavirus reinfection and there were positives to take from the report. First and foremost, he was asymptomatic. Although reinfected with Sars-Cov-2, his immune system swung into action fast and contained the virus without him knowing.
Many researchers took heart from the case, but since the patient came to light a flurry of reinfections around the world have raised fresh concerns. Within days of the Hong Kong case being made public, doctors in the US reported that a 25-year-old man from Reno, Nevada, had been hospitalised with a Covid-19 reinfection after shrugging off an earlier brush with the disease. More cases soon followed. While most infections were no worse the second time around, a good number cropped up – in the US, the Netherlands, Ecuador and India – where the reinfection was more severe.
“It’s really hard to find a pattern right now,” said Akiko Iwasaki, a professor of immunobiology at Yale University who has been following cases of reinfection closely. “Essentially every case is different.”
So far, only two dozen or so reinfections have been confirmed worldwide in a pandemic that has infected more than 30 million people. For now at least, reinfection seems uncommon. But scientists point out that confirming reinfection is no easy task and many cases are missed. Read more >>