One year landscape of the inactivated virus vaccine triggered RBD-specific IgG, IgM and IgA responses against the Omicron variant

We reported the first map of vaccine stimulated RBD-specific antibody responses (IgG, IgM and IgA) against the Omicron variant. We generated the map using a protein microarray, by analyzing longitudinal sera collected spanning one year from individuals immunized with 3 doses of an inactivated virus vaccine. The IgG response to RBD-Omicron is: 1/3-1/5 that of RBD-wild type; ~6x higher for the booster dose vs. the 2nd dose; and reaches the plateau in about two weeks after the booster dose, then drops ~5x in another two weeks. Similar results were also obtained for IgM and IgA. Because of the high correlation between RBD-specific antibody response and the neutralization activity to authentic virus, we at least indirectly revealed the landscape of antibody protection against the Omicron variant throughout the vaccination stages. Our results strongly support the necessity of booster vaccination. However, post-booster vaccination may need to be considered.