Lung transplant recipients (LTRs) are immunosuppressed and at high risk from COVID-19, but meaningful quantitative comparisons of their humoral immunity versus non-immunosuppressed persons are scarce. Serum anti-spike receptor binding domain antibodies were quantified in healthy controls after: primary vaccination, mild COVID-19, one vaccination after mild COVID-19, or severe COVID-19. LTRs were assessed after: primary vaccination, a third "booster" vaccination, or severe COVID-19. Controls showed a spectrum of robust responses from vaccination to severe COVID-19. LTRs exhibited markedly diminished responses to primary vaccination, minimally increased by a third "booster." Multivariable logistic regression of LTRs showed being ≥3 years after transplantation and receiving a booster vaccine dose were associated with higher vaccination antibody levels. However, the LTR COVID-19 survivors had comparable antibody levels to control COVID-19 survivors, suggesting that greater antigenic stimulus can elicit robust humoral immunity. Further study will be required to determine if revised vaccination strategies can replicate these responses.
Keywords: COVID-19; humoral immunity; immunosuppression; mRNA vaccination.
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