Background Liver transplant (LT) recipients frequently show no or low response after two SARS-CoV-2
vaccinations. However, the relevance of different clinical risk factors (RF) for a
suboptimal response is still unanswered.
Methods Anti-SARS-CoV-2 antibody titers of 141 LT patients determined after the second vaccination
assigned them to low ( < 100 BAU/ml) or high response. The relevance of previously
identified clinical RF for low response (diabetes, chronic kidney injury, hypertension
or age > 65y) and antiproliferative immunosuppression were now analyzed in detail.
Results The full clinical data set was available in 101 patients (55 low, 46 high responders).
In total, 82% of low and 52% of high responders had one or more clinical RF. The risk
of low response for patients having at least one, two or three clinical RF increased
from 31% (N=10 of 32) to 65% (N=45 of 69), 86% (N=32 of 37) and 93% (N=13 of 14),
respectively. If all four RF were present, the risk of low response increased to 100%
(N=6 of 6). Also, a more frequent use of MMF or mTOR-inhibitors was detected in low
responders (74%) compared to high responders (37%). Of the 26% (N=12) of low responders
not receiving antiproliferative immunosuppression the majority had one (25%) or more
(50%) clinical RF.
Conclusion If clinical RF are present, the risk of low SARS-CoV-2 vaccination response increases
1.6-fold and with the number of RF. These data can help to identify patients under
immunosuppression with the highest risk of suboptimal response to further SARS-CoV-2
vaccinations.
