Even people with minor illness from the coronavirus can develop antibodies that could leave them immunised for several weeks or more, according to an early French study that tested hospital staff with mild infections. Researchers said the results, which have not yet been peer reviewed, were “encouraging” since little is known about the mechanisms of immunity against the novel coronavirus, especially in people with minor forms of the disease. “We knew that people with severe forms of the disease developed antibodies within 15 days of the onset of symptoms,” said Arnaud Fontanet, head of the global health department at the Institut Pasteur, which conducted the research with the University Hospital in Strasbourg. “We now know that this is also true for those who develop minor forms, even if the rates of antibodies are probably weaker.” The study was carried out on 160 members of staff at two hospital sites in Strasbourg who had all tested positive for COVID-19 and suffered mild forms of the disease.