Delayed exacerbation of COVID-19 pneumonia in vaccinated kidney transplant recipients receiving immunosuppressants: a case series.

Coronavirus disease 2019 (COVID-19) increases the risk of mortality and hospitalization in immunocompromised patients, including kidney transplant recipients (KTRs) receiving immunosuppressants. Several vaccines for COVID-19 have been developed and proven effective in decreasing the incidence of COVID-19 and the rate of progression to severe COVID-19. However, breakthrough infections have also been reported in vaccinated patients. We report cases from our center of delayed exacerbated pneumonia from COVID-19 in vaccinated KTRs receiving immunosuppressants. Of the 900 KTRs who had been vaccinated for COVID-19 and were followed up at our center from January 1, 2022, to April 30, 2022 (during the Omicron variant outbreak), 126 contracted COVID-19 (incidence rate, 14%). Thirty-four (27%) in this group were hospitalized due to COVID-19. Twenty patients did not have pneumonia but had symptoms of upper respiratory tract infection or diarrhea, which improved with conservative treatment. Nine of the 14 patients with pneumonia had delayed onset or exacerbated pneumonia 1 week after their COVID-19 diagnosis. They were treated with remdesivir, and most recovered. One patient died due to progressive pneumonia and pneumothorax. It is important that KTRs who are taking immunosuppressants be observed closely and for a prolonged period after a COVID-19 diagnosis, irrespective of their COVID-19 vaccination status.