This is a large-scale study testing blood samples and swabs obtained from healthcare workers who work in a clinical setting to see if infection with COVID-19 protects them from future episodes of infection. It was set up by PHE in April 2020 in response to the need to assess the risk of re-infection in those who have tested positive for antibodies. Since the introduction of COVID-19 vaccination among healthcare workers, it is also a leading source of information on vaccine effectiveness.

The aim of SIREN is to establish whether healthcare workers who test positive for COVID-19 antibodies are protected from future episodes of infection. We will follow healthcare workers for at least a year and study their immune response to the virus causing COVID-19. We will do this by collecting baseline data, such as their history of COVID-19 infection and potential exposure to the virus via an online survey. Continued details of exposure and any new symptoms is monitored in regular follow-up surveys. A swab test (PCR) is completed every other every other week in order to detect mild cases of COVID-19 or cases without symptoms. Blood samples are taken each month to determine whether individuals have antibodies. Since January 2021, vaccination data has been collected, in order to inform vaccine effectiveness estimates among healthcare workers.

Public Health England is not currently accepting requests to access this dataset.