The team at the Rockefeller University in New York City, first studied 3,595 patients from 38 countries with critical COVID-19, meaning that the individuals were ill enough to be admitted to an intensive-care unit.

Overall, 13.6 per cent of these patients possessed autoantibodies, with the proportion ranging from 9.6 per cent of those below the age of 40, up to 21 per cent of those over 80. Autoantibodies were also present in 18 per cent of people who had died of the disease.

The researchers suspected that these devious antibodies were a cause, rather than a consequence, of critical Covid.