Antibody response to ChAdOx1 nCoV-19 (Covishield®) vaccine in people on maintenance hemodialysis.

Introduction: People on renal replacement therapy (RRT) have a high risk of COVID-19 infection and subsequent death. COVID-19 vaccination is strongly recommended for those on RRT. Data are limited on the immune response of the ChAdOx1 nCoV-19/AZD1222 (Covishield®) vaccine in patients on RRT.

Methods: A prospective cohort of adult (age > 18 years), on RRT in the form of hemodialysis were included and received two intramuscular doses of Covishield®. A blood specimen of 5.0 mL was collected at two time points, within a few days before administering the first dose of the vaccine and at 4-16 weeks after the second dose. According to their prior COVID-19 infection status, the participants were grouped as (i) prior symptomatic COVID-19 infection, (ii) prior asymptomatic COVID-19 infection, and (iii) no prior COVID-19 infection.

Results: A large proportion (81%) of participants had anti-spike antibodies (ASAb) before vaccination, and a reasonable proportion (30%) also had neutralizing antibodies (NAb). The titer of ASAb was relatively low (207 U/mL) before vaccination. The ASAb titer (9405 [1635-25,000] U/mL) and percentage of NAb (96.4% [59.6-98.1%]) were markedly increased following the administration of two doses of the vaccine. The participants' prior COVID-19 exposure status did not influence the rise in ASAb titer and NAb percentage. Further, administering two doses of the Covishield vaccine helps them achieve a high ASAb titer.

Conclusion: Two doses of ChAdOx1 nCoV-19/AZD1222 (Covishield®) vaccine, given 12 weeks apart, achieve a high titer of ASAb and a high percentage of NAb in people on hemodialysis.