a study led by Public Health England shows that it is possible to catch COVID-19 more than once but those who have caught it once are protected from catching it again for at least five months.
Past infection gave people 83% protection from reinfection, compared with those who had never had the virus, scientists found.
But experts warn some people do catch Covid-19 again – and can infect others.
And officials stress people should follow the stay-at-home rules – whether or not they have had the virus.
Prof Susan Hopkins, who led the study, said the results were encouraging, suggesting immunity lasted longer than some people feared, but protection was by no means absolute.
It was particularly concerning some of those reinfected had high levels of the virus – even without symptoms – and were at risk of passing on it on to others, she said.
“This means even if you believe you already had the disease and are protected, you can be reassured it is highly unlikely you will develop severe infections but there is still a risk that you could acquire an infection and transmit to others,” she added.
“Now more than ever, it is vital we all stay at home to protect our health service and save lives.”
From June to November 2020, almost 21,000 healthcare workers across the UK were regularly tested to see whether they:
currently had the coronavirus
had had it previously
Of those who had no antibodies to the virus, suggesting they had never had it, 318 developed new infections within this timeframe, the tests indicated.
But among the 6,614 with antibodies, this figure was just 44.