A study of more than 12,000 healthcare workers showed that people who had already been infected with COVID-19 may be protected from re-infection for at least six months. This data has not yet been peer reviewed. Researchers at the University of Oxford and Oxford University Hospitals (OUH) NHS Foundation Trust studied frontline workers in the UK over the course of 30 weeks, testing for both antibodies and virus. They found that very few people who had antibodies to SARS-CoV-2 (indicating past COVID-19 infection) tested positive for the virus again within six months. Of 1,246 people with antibodies, only three tested positive for the virus a second time - and none of them had symptoms. Conversely, 89 people who did not have those antibodies were infected during the same time period.
One of the study's authors said, "This is really good news because we can be confident that, at least in the short term, most people who get COVID-19 won’t get it again [...] being infected with COVID-19 does offer protection against reinfection for most people for at least six months."