#6171 Seroprevalence of Covid-19 Infection Based on Igg Antibody Against Nucleocapsid Protein (Np) and Spike Protein (S) in Hemodialysis Patients

Abstract

Background and Aims Maintenance hemodialysis (MHD) patients have been identified as a high-risk group for COVID-19 infection. Serological testing can be used to monitor disease prevalence & evaluate screening measures & protocols aiming at limiting transmission within dialysis units. This study was conducted to observe the sero prevalence of COVID-19 infection among maintenance hemodialysis patients. Method The study was conducted during the 3rd wave of covid-19 infection. Total 194 in-center MHD patients were included from three dialysis centers. Relevant history regarding covid-19 symptom, testing, managements and vaccination were collected. During our study a serum sample was collected to test IgG antibody against nucleocapsid protein (NP) (cut-off positive when >1.5) and spike protein (S) (cut-off positive when >50 AIU/L) of COVID-19 infection and tested by Chemiluminescent microparticle immunoassay (CMIA) method developed by Abbott (FDA-EUA approved). Results Mean age of the MHD subjects was 48±12 years where male was 60%. Duration of MHD was 31±22 (6-120) months. Renal pathology was DN in 31%, possible GN 31%,HTN 19% and rest from others .From records past covid infection was clinically diagnosed in 39% of which 10% based on RT-PCR and another 29% fell into suspected category (i.e. symptom with/or suggestive serology). Presentation pattern was mild in 75%, moderate 15% (requiring oxygen), severe in 5% (requiring hospitalization) and asymptomatic rest 5%. Vaccine against covid-19 was availed by 38%. In vaccinated vs. non-vaccinated patients the IgG for NP was positive in 63% vs. 561%(P = 0.65) and IgG for S in 99% vs. 98%(P = 0.56). These indicate naturally acquired immunity in most before any vaccination. The IgG titer against spike (S) protein between vaccinated and non-vaccinated groups was 7743±8920 and 5386± 6839 AIU/L (p = 0.06). The correlation study showed that IgG titer against S has no correlation with dialysis duration, age, BMI, Hb%, serum albumin or Kt/V. Similarly IgG titer against NP shows mostly no significant correlation with laboratory parameters. Conclusion These data demonstrate that seroprevalence in hemodialysis population based on antibody against nucleocapsid protein shows only half infected by SARS-CoV-2 where as antibody against spike protein indicates larger number of patients are naturally infected even before vaccinated. Therefore for seroprevalence studies both antibody testing should be used to identify greater population infected until more sensitive tools are established.