ASSOCIATION BETWEEN IMMUNE SYSTEM FUNCTION AS DETERMINED BY HEPATITIS B INFECTION/VACCINATION STATUS AND RISK OF COVID-19 INFECTION

ABSTRACT

BACKGROUND AND AIMS: Since the beginning of the COVID-19 pandemic in early 2020, >290 million people were infected by SARS-CoV-2 and >5.4 million have died from or with COVID-19 (https//coronavirus.jhu.edu/). Patients with chronic health conditions such as end-stage kidney disease (ESKD) experience particularly high morbidity and mortality because of COVID-19. ESKD patients on hemodialysis are widely vaccinated for hepatitis B (HBV) and seroconversion is routinely measured. This practice presents a rare opportunity to study immune function on a wide scale. It can be reasonably assumed that patients who are able to produce a vaccinal or post-HBV antibodies titers have a better immune function than those who are unable to mount such a serological response. We aim to jointly analyze results of SARS-CoV-2 RT-PCR and hepatitis B serology to determine if presence of vaccinal or post-HBV antibodies is associated with likelihood of developing COVID-19 infection. METHOD: Patients who were tested for COVID-19 at Fresenius Medical Care North America dialysis clinics from May 2020 to September 2020 were included in this analysis. HBV infection/vaccination status, demographic parameters and clinical parameters were obtained from the medical record. Nasopharyngeal swab specimen was tested via RT-PCR to detect presence of SARS-CoV-2. Patients were categorized as having good immune function or poor immune function based on vaccinal and post-HBV sero-status. Patients who were vaccinated against HBV but did not seroconvert were considered to have poor immune function. On the other hand, patients who mounted vaccinal or post-HBV antibodies were considered to have good immune function. Univariate and multivariate logistic regression were utilized to study the association between immune function and other demographic, anthropometric and clinical parameters on the likelihood of not being diagnosed with COVID-19. Four models were constructed Model 1 unadjusted;Model 2 adjusted for age. Model 3 adjusted for age, gender, race, ethnicity, body mass index (BMI). Model 4 adjusted for parameters in model 3 and dialysis vintage (in years), diabetes and congestive heart failure (CHF). RESULTS: 11 870 patients were included in this analysis. 54% patients were male, 33% were Black, 24% of the patients were Hispanic, 69% had diabetes and 22% had CHF. Patients were 61.2 ± 14.4 years old with dialysis vintage of 3.9 ± 3.9 years, BMI of 29.6 ± 9.7 kg/m2 and eKt/V 1.5 ± 0.3. Of these patients, 21% had poor immune function and 79% had good immune function. Results of the logistic regression models are shown in Table 1. In the unadjusted model, poor immune function was associated with an increased likelihood of being diagnosed with COVID-19. In models, 2, 3 and 4 age, vintage and presence of diabetes were all significantly associated with a higher likelihood of being diagnosed with COVID-19. However, poor immune function was not a significant predictor of COVID-19 diagnosis in the adjusted models. CONCLUSION: Patients who have vaccinal or post-HBV antibodies did not have a lower likelihood of COVID-19 compared with patients who were unable to mount an adequate vaccinal or post-HBV antibody response. Response to HBV vaccination or infection may not be adequate to characterize a patient as having good immune response. Other factors that are routinely measured in hemodialysis patients, which may allow us to make inferences about a patient's immune function should be explored.