“If people can be reinfected easily, it could also have implications for vaccination programmes, as well as our understanding of when and how the pandemic will end.”

‘We still don’t know enough’

The Nevada patient’s doctors, who first reported the case in a non peer-reviewed paper in August, said sophisticated testing showed that the virus strains associated with each bout of infection were genetically different.

“These findings reinforce the point that we still do not know enough about the immune response to this infection,” said Paul Hunter, a professor in medicine at Britain’s University of East Anglia.

Brendan Wren, a professor of vaccinology at the London School of Hygiene & Tropical Medicine, said the Nevada case was the fifth confirmed example of reinfection worldwide.

“The demonstration that it is possible to be reinfected by Sars-CoV-2 may suggest that a Covid-19 vaccine may not be totally protective,” he said.

“However, given the [more than] 40 million cases worldwide, these small examples of reinfection are tiny and should not deter efforts to develop vaccines.”

Reuters