Post-vaccination analysis of anti-spike antibody responses in kidney transplant recipients with and without COVID-19 infection in a tertiary care centre, India

Background. To investigate the anti-spike antibody response to vaccination in kidney transplant recipients (KTRs) previously infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as compared with KTRs with no history of coronavirus disease 2019 (COVID-19) from India. Methods. SARS-CoV-2 spike immunoglobulin (Ig) G antibody response was measured in 105 post-COVID-19 KTRs with PCR-confirmed SARS-CoV-2 infection who received either no vaccination (cohort 1), a single dose (cohort 2) or two doses (cohort 3) of vaccine and compared with 103 two-dose vaccinated COVID-19-naive KTRs with no history of COVID-19 (cohort 4). Results. Out of 103 COVID-19-naive two-dose vaccinated KTRs, <50% became seropositive with anti-spike antibody titres >50 arbitrary unit/mL subsequent to complete vaccination, the seroconversion rate being comparable in subjects receiving Covishield (TM) versus Covaxin (TM) vaccines. However, the seropositive KTRs vaccinated with Covishield (TM) had higher anti-spike antibody titres as compared with those who received Covaxin (TM). We observed higher anti-SARS-CoV-2 spike antibody levels in post-COVID-19 KTRs after one dose of vaccine as compared with COVID-19-naive two-dose vaccinated KTRs. Importantly, the second dose in post-COVID-19 KTRs did not significantly increase anti-spike antibody levels compared with the single-dose recipients. Conclusions. Our data present that in KTRs with previous SARS-CoV-2 infection, a single dose of vaccine (Covishield (TM)) may be effective in mounting an optimal immune response. In contrast, COVID-19-naive two-dose vaccinated KTRs respond poorly (<50%) to the current recommendation of a two-dose regimen in India.