The third vaccine dose significantly reduces susceptibility to the B.1.1.529 (Omicron) SARS‐CoV‐2 variant

Abstract

The main coronavirus disease 2019 (COVID‐19) vaccine formulations used today are mainly based on the wild‐type severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) spike glycoprotein as an antigen. However, new virus variants capable of escaping neutralization activity of serum antibodies elicited in vaccinated individuals have emerged. The Omicron (B.1.1.529) variant caused epidemics in regions of the world in which most of the population has been vaccinated. In this study, we aimed to understand what determines individual's susceptibility to Omicron in a scenario of extensive vaccination. For that purpose, we collected nasopharynx swab (n = 286) and blood samples (n = 239) from flu‐like symptomatic patients, as well as their vaccination history against COVID‐19. We computed the data regarding vaccine history, COVID‐19 diagnosis, COVID‐19 serology, and viral genome sequencing to evaluate their impact on the number of infections. As main results, we showed that vaccination in general did not reduce the number of individuals infected by Omicron, even with an increased immune response found among vaccinated, noninfected individuals. Nonetheless, we found that individuals who received the third vaccine dose showed significantly reduced susceptibility to Omicron infections. A relevant evidence that support this finding was the higher virus neutralization capacity of serum samples of most patients who received the third vaccine dose. In summary, this study shows that boosting immune responses after a third vaccine dose reduces susceptibility to COVID‐19 caused by the Omicron variant. Results presented in this study are useful for future formulations of COVID‐19 vaccination policies.

Neutralizing antibody response after immunization with a COVID‐19 bivalent vaccine: Insights to the future

“…Although PRNT, and FRNT are considered golden standard, the CPE‐VNT has shown to be particularly useful for studying larger sets of samples 18,26,27 . The same technique has been used in our previous studies 13,14 and we preferred not to change the methodology in the present study. Nevertheless, we present robust statistical analysis that support our main statements and conclusions.…”

“…The group that received the bivalent vaccine had an average time interval of 7.92 ± 1.12 months between the last two doses, and a 0.4 ± 0.16 months' interval between the last dose and sampling. In addition, none of the participants of this study were infected with SARS‐CoV‐2 for at least 1 year before the study period, as determined by the lack of registered evidence of illness (COVID‐19), confirmed by RT‐qPCR and presentation of symptoms, as previously described 13,14 . Demographic information (Supplementary Material ) as well as serum samples were collected.…”

“…Demographic information (Supplementary Material ) as well as serum samples were collected. An enzyme linked immunosorbent assay (ELISA) was carried out to measure the serum levels of antibodies capable of recognizing the S and the nucleocapsid (N) proteins, as previously described 13,15 . Neutralization assays using the WT SARS‐CoV‐2, the original Omicron variant (BA.1), and its subvariants FE.1.2 or BQ.1.1 were carried out, as previously described 13 .…”

“…13,15 Neutralization assays using the WT SARS-CoV-2, the original Omicron variant (BA.1), and its subvariants FE.1.2 or BQ.1.1 were carried out, as previously described. 13 Additionally, we conducted immunoinformatic analysis to highlight unique and shared conserved NAb epitopes between SARS-CoV-2 variants (WT, BA.1, BA.4, BA.5, and BQ.1.1), as previously described. 16,17 All the research complied with all relevant ethical and biosafety guidelines.…”

“…In addition, none of the participants of this study were infected with SARS-CoV-2 for at least 1 year before the study period, as determined by the lack of registered evidence of illness (COVID- 19), confirmed by RT-qPCR and presentation of symptoms, as previously described. 13,14 Demographic information (Supplementary Material S1) as well as serum samples were collected. An enzyme linked immunosorbent assay (ELISA) was carried out to measure the serum levels of antibodies capable of recognizing the S and the nucleocapsid (N) proteins, as previously described.…”