Study cohort
This study received ethical approval from the Wales Research Ethics Committee 5 (IRAS number: 286991). To investigate T cell responses in naturally infected individuals, participants from across Wales and England were recruited to the project between June-December 2020. All participants gave written, informed consent prior to inclusion. At the time of blood sample collection, corresponding details of prior test results for SARS-CoV-2 infection, confirmed by using PCR with reverse transcription from a nose and throat swab performed by public health bodies at accredited laboratories were obtained via questionnaire. Those that had a positive PCR test were assigned to the ‘Confirmed infection (PCR positive’) cohort (n=29). Participants were also asked if they had ever tested positive for SARS-CoV-2 via a lateral flow test, and to note any COVID-19-related symptoms they had experienced as well as record any close contact they had with persons who had been confirmed positive by PCR. Those that had a positive lateral flow test, experienced COVID-19-like symptoms or had close contact with a positive individual were assigned to the ‘Suspected infection/exposure’ cohort (n=30). All other individuals were assigned to the ‘No history of exposure’ cohort (n=69). None of the participants were hospitalised due to COVID-19 at any time before or during the study.
To investigate T cell responses in vaccinated individuals, participants from across Wales, England and the US were recruited to the project between December 2020 and March 2021. All participants gave written, informed consent prior to inclusion. At the time of blood sample collection, details of prior test results for SARS-CoV-2 infection and details of SARS-CoV-2 vaccinations including date and vaccine manufacture were obtained via questionnaire: 26 donors received the Pfizer-BioNTech vaccine, 5 received the Oxford-AstraZeneca vaccine and 1 received the Johnson and Johnson/Janssen vaccine.