Group Tx-vac-flu (n=18) Tx-no vac-flu (n=6) Healthy-flu (n=12) Tx-vac-no flu (n=13) Type of influenza A 13 5 4* N/A B 5 2 8 Influenza PCR cycle threshold Mean 23.3 26.6 24.5 Range 8.3 - 30.9 16.9 - 35.5 20.3 - 31.4 Median 25.3 26.7 † 24.3# Interquartile Range 20.6 - 27.5 23.5 - 29.9 20.8 - 26.2 Tx-vac-flu=Transplant recipients who developed influenza despite influenza vaccination Tx-no vac-flu=Transplant recipients who developed influenza in the absence of influenza vaccination Healthy-flu=Healthy people who developed influenza Tx-vac-no flu=Transplant recipients who received influenza vaccination and did not develop influenza N/A=not applicable. *P=0.04, †P=0.3, #P=0.9; compared to the tx-vac-flu group.

Table 3: Virological characteristics.