LAUSR

Immunosuppressed organ‐transplanted patients are considered at risk for severe forms of COVID‐19. Moreover, exaggerated innate and adaptive immune responses might be involved in severe progression of the disease. However, no data on the immune response to SARS‐CoV‐2 in transplanted patients are currently available. Here, we report the first assessment of antibody and T cell responses to SARS‐CoV‐2 in 11 kidney‐transplanted patients recovered from RT‐PCR–confirmed (n = 5) or initially suspected (n = 6) COVID‐19. After reduction of immunosuppressive therapy, RT‐PCR–confirmed COVID‐19 transplant patients were able to mount vigorous antiviral T cell and antibody responses, as efficiently as two nontherapeutically immunosuppressed COVID‐19 patients on hemodialysis. By contrast, six RT‐PCR–negative patients displayed no antibody response. Among them, three showed very low numbers of SARS‐CoV‐2–reactive T cells, whereas no T cell response was detected in the other three, potentially ruling out COVID‐19 diagnosis. Low levels of T cell reactivity to SARS‐CoV‐2 were also detected in seronegative healthy controls without known exposure to the virus. These results suggest that during COVID‐19, monitoring both T cell and serological immunity might be helpful for the differential diagnosis of COVID‐19 but are also needed to evaluate a potential role of antiviral T cells in the development of severe forms of the disease.