Significance of PPD Test for the Relationship Between BCG Vaccine and COVID-19 in Patients on Kidney Transplant Waiting List

BACKGROUND: The aim of this study was to determine the relationship between purified protein derivative of tuberculin (PPD) values, an indicator of BCG protection, and COVID-19 disease in patients with end-stage renal disease (ESRD) on the kidney transplant waiting list. METHODS: Age, sex, dialysis type, ERSD etiologies, and PPD values of patients on the renal transplant waiting list were recorded. SARS-CoV-2 PCR data, whether the patients were previously infected with the virus, and, if infected, the severity of the disease were noted. Data were statistically compared. RESULTS: PCR of 87 (47.02%) of 185 patients were studied; 107 of the patients were male and 78 were female, with a mean age of 52.8 years. The test result was positive for 28 patients. Of the patients for whom PCR was studied, 41 had a negative PPD result, while 46 had a positive PPD result. There was no correlation with SARS-CoV-2 PCR positivity in patients with a PPD ≤ 5 mm and > 5 mm. However, patients with pneumonic infiltration who required hospitalization had a significantly higher PPD value. CONCLUSIONS: The PPD measurement, which is an indicator of BCG protection, might be a significant parameter for predicting the course of the disease in SARS-CoV-2 pneumonia.