For patient group: Prior exposure to SARS-CoV-2 (positive serology). Have previously received a COVID-19 vaccination. Due to receive a transplant within the ensuing 6 months. Control/comparison group: Prior exposure to SARS-CoV-2 (positive serology). Have previously received a COVID-19 vaccination.

For patient group: Prior exposure to SARS-CoV-2 (positive serology). Have previously received a COVID-19 vaccination. Due to receive a transplant within the ensuing 6 months. Control/comparison group: Prior exposure to SARS-CoV-2 (positive serology). Have previously received a COVID-19 vaccination.