Scientists from Hong Kong University have reported the case of an apparently young, healthy patient who was re-infected with Covid-19, four-and-a-half months after the first infection.
Using genomic sequencing, they discovered that the second attack as a virus was “clearly different” from the first infection rather than just a continuation or re-emergence of the original.
Scientists know that people infected with coronavirus develop an immune response when their bodies fight the virus, and this helps protect them from returning. But it is not clear how strong this protection is or how long it will last.
If humans can catch the virus more than once, then a vaccine may be needed to protect many more people – although those who are most seriously ill have a greater immune response than those with mild symptoms.
Other coronaviruses, such as the common cold, re-infect humans, so it is not surprising that Sars-CoV-2 – the virus that causes Covid-19 – could do the same.
But the World Health Organization says it is important not to jump to any conclusions based on the experience of one in 23 million patients around the world.
The full research document has not yet been published, so some aspects of this case are not yet clear.
It turns out that when this person was infected for the second time, they had no symptoms – and the infection was picked up by airport screening tests, suggesting that the patient was not well. More population-based studies are needed before firm conclusions about re-infection can be drawn.
