Comparative humoral response of mRNA and inactivated vaccines against COVID-19 in healthy adults aged 60 years and older.

INTRODUCTION

A vaccine against coronavirus disease 2019 (COVID-19) is critically needed for older adults because of the increased morbidity and mortality rates.

METHODOLOGY

In this prospective study, we analysed the titre magnitude of the IgG antibodies directed against the SARS-CoV-2 Spike Protein S1 (S1-RBD) antigen in both CoronaVac and Pfizer-BioNTech groups. The samples were tested to detect antibodies that bind to the receptor-binding domain of the spike protein of SARS-CoV-2 using the Enzyme-Linked Immunosorbent Assay (ELISA) technique with SARS-CoV-2 IgG II Quant. The cut-off value was > 50 AU/mL. GraphPad Prism software was used. Statistical significance was defined at p < 0.05.

RESULTS

The CoronaVac group (12 females, 13 males) had a mean age of 69.64 ± 1.38 years. The Pfizer-BioNTech group (13 males, 12 females) had a mean age of 72.36 ± 1.44 years. The anti- S1-RBD titre decrease rate from the 1st to the 3rd month for CoronaVac and Pfizer-BioNTech groups was 74.31% and 86.48%, respectively. There was no statistically significant difference in the antibody titre between the 1st month and 3rd month for the CoronaVac group. However, there was a significant difference between the 1st and 3rd month in the Pfizer-BioNTech group. In addition, there was no statistically significant difference in the genders between the 1st and 3rd month of the antibody titres for both the CoronaVac Pfizer-BioNTech group.

CONCLUSIONS

The levels of anti-S1-RBD, the preliminary outcome data of our study, represents one piece of the puzzle of humoral response and duration of vaccination protection.