Risk Factors for Impaired Cellular or Humoral Immunity after Three Doses of SARS-CoV-2 Vaccine in Healthy and...

Background: We aimed to identify the risk factors for impaired cellular and humoral immunity after three doses of the SARS-CoV-2 vaccine. Methods: Six months after the third vaccine dose, T-cell immunity was evaluated using interferon-gamma release assays (IGRAs) in 60 healthy and 139 immunocompromised (IC) individuals, including patients with hematologic malignancy (HM), solid malignancy (SM), rheumatic disease (RD), and kidney transplantation (KT). Neutralizing antibody titers were measured using the plaque reduction neutralization test (PRNT) and surrogate virus neutralization test (sVNT). Results: T-cell immunity results showed that the percentages of IGRA-positive results using wild-type/alpha spike protein (SP) and beta/gamma SP were 85% (51/60) and 75% (45/60), respectively, in healthy individuals and 45.6% (62/136) and 40.4% (55/136), respectively, in IC individuals. IC with SM or KT showed a high percentage of IGRA-negative results. The underlying disease poses a risk for impaired cellular immune response to wild-type SP. The risk was low when all doses were administered as mRNA vaccines. The risk factors for an impaired cellular immune response to beta/gamma SP were underlying disease and monocyte%. In the sVNT using wild-type SP, 12 of 191 (6.3%) individuals tested negative. In the PRNT of 46 random samples, 6 (13%) individuals tested negative for the wild-type virus, and 19 (41.3%) tested negative with omicrons. KT poses a risk for an impaired humoral immune response. Conclusions: Underlying disease poses a risk for impaired cellular immune response after the third dose of the SARS-CoV-2 vaccine; KT poses a risk for impaired humoral immune response, emphasizing the requirement of precautions in patients.