ABSTRACT
Background Kidney transplant recipients (KTRs) are at high risk from COVID-19, vaccination is significant efficacy to prevent and reduce the severity of infection. Omicron infections are less severe than previous strains, but breakthrough disease is more common, thus we conducted this study to observe the vaccine efficacy in our KTRs. Methods The surge Omicron variant since May 2022, we retrieved 365 KTRs at least their 1st dose of various COVID vaccines until June 30, 2022. KTRs (n=168) at least post 2nd vaccination to assess their outcomes until September 30, 2022, which was the time before open the border for tourism. Results The antibody response in KTRs after the 1st and 2nd dose SARS-CoV-2 vaccines demonstrated significant increase from the 1st dose (median: 0.4;IQR: 0.4-8.4 U/mL, P < 0.001) to the 2nd dose (median: 57.5;IQR: 0.4-799.2 U/mL), and the response rate rise from 32% to 65% (P < 0.001). SARS-CoV-2 infection was identified in 14/365 (3.8%) at least post 1st dose, and 7/187 (3.7%) at least 7 days beyond post 2nd dose. The majority of KTRs had a mild course but 3 (17%) were hospitalized due to pneumonia. Conclusions our data demonstrate lower response rate and anti-S titers after 2nd dose vaccination in KTRs than general population, but lower incidence of SARS-CoV-2 infection after vaccination during Omicron pandemic. The breakthrough infections found in ordinary vaccinated KTRs, however, we need to emphasize the importance of vaccination and boosters to prevent severe illness, hospitalizations, and death amongst those developing infection.