ABSTRACT
BACKGROUND: Vaccines that prevent SARS-CoV-2 infection are considered the most promising approach to modulating the pandemic. There is scarce evidence on the efficacy and safety of different vaccine prime-boost combinations in MHD patients since most clinical trials have used homologous mRNA vaccine regimens. METHODS: This prospective observational study assessed the immunogenicity and safety of homologous CoronaVac® (SV-SV), ChAdOx1 nCoV-19 (AZD1222) (AZ-AZ), and the heterologous prime-boost of SV-AZ, among MHD patients. RESULTS: A total of 130 MHD participants were recruited. On day 28, after the second dose, seroconversion results of the surrogate virus neutralization test were not different between vaccine regimens. The magnitude of the receptor-binding domain-specific IgG was highest among the SV-AZ. Different vaccine regimens had a distinct impact on seroconversion, for which the heterologous vaccine regimen demonstrated a higher probability of seroconversion (OR 10.12; p = 0.020, and OR 1.81; p = 0.437 for SV-AZ vs. SV-SV, and SV-AZ vs. AZ-AZ, respectively). There were no serious adverse events reported in any of the vaccine groups. CONCLUSIONS: Immunization with SV-SV, AZ-AZ, and SV-AZ could generate humoral immunity without any serious adverse events among MHD patients. Using the heterologous vaccine prime-boost seemed to be more efficacious in terms of inducing immunogenicity.
ABSTRACT
This study aimed to evaluate the correlation between in-house and commercial binding-specific IgG antibodies and between in-house and commercial SARS-CoV-2 surrogate virus neutralization tests (sVNT). Samples from healthcare workers who received vaccines against SARS-CoV-2 were tested for RBD-specific antibody, S-specific antibody, and in-house ELISA, commercial sVNT, and in-house sVNT, against wild-type SARS-CoV-2. Three hundred and five samples were included in the analysis. The correlation between S-specific binding antibodies and in-house ELISA was 0.96 (95% CI 0.96-0.97) and between RBD-specific antibodies and in-house ELISA was 0.96 (95% CI 0.95-0.97). The Cohen's kappa between in-house sVNT and the commercial test was 0.90 (95% CI 0.80, 1.00). If using 90% inhibition of sVNT as the reference standard, the optimal cut-off value of RBD-specific antibodies was 442.7 BAU/mL, the kappa, sensitivity, and specificity being 0.99, 99%, and 100%, respectively. The optimal cut-off value of S-specific antibodies was 1155.9 BAU/mL, the kappa, sensitivity, and specificity being 0.99, 100%, and 99%, respectively. This study demonstrated a very strong correlation between in-house ELISA and 2 commercial assays. There was also a very strong correlation between in-house and commercial SARS-CoV-2 sVNT, a finding of particular interest which will inform future research.