Waning antibody response and cellular immunity 6 months after third dose SARS-Cov-2 mRNA BNT162b2 vaccine in kidney transplant recipients

number of spike– reactive T cells decreased from 280 (IQR: 120– 600) to 85 SFC/106 CD3 + T cells (IQR: 35– 155) ( p < .0001) after the third dose with a median decrease of 62.3% (IQR: −86.7%– 38.2%) (Figure 1B). None of the patients developed symptomatic SARS- Cov- 2 infection during the follow- up. We documented here for the first time the decline of both humoral and cellular immunity 6 months after a third mRNA vaccine dose in KTR responders. Such rapid decline is of concern because of the high probability of reduced vaccine effective-ness against the delta (B.1.617.2) variant and breakthrough infection in KTR. In this subgroup of KTR responders, a booster dose of mRNA vaccine should thus be considered 3 to 6 months following the third injection as recommended now by the French Health authority.