A Public Health England (PHE) study (SIREN) finds past infection with coronavirus (COVID-19) provides about 83% protection against reinfection (immunity) for at least 5 months from first becoming sick, but people may still carry the virus in their nose and throat and therefore risk transmitting it to others.
PHE has been regularly testing tens of thousands of healthcare workers across the UK since June for new COVID-19 infections. They have also been testing for the presence of antibodies, which suggest people have been infected before. PHE scientists have concluded that naturally acquired immunity as a result of past infections provide 83% protection against reinfection, compared to people who have not had the disease before. This appears to last for at least 5 months from first becoming sick.
The SIREN study will continue to assess whether immunity may last for longer; however, this means people who contracted the disease in the first wave last summer may now be vulnerable to catching it again.