IL6 and susceptibility to pneumonia measurement: Considering our consistent results and the detected relationship between neutralizing activity against Omicron, IL-6 levels, and cTfh proportions, we believe that these limitations were not likely to have meaningfully affected our findings, which elucidated the differences in acute immune dynamics to Omicron infection between vaccinated and unvaccinated, with and without pneumonia, and between Omicron and the precedent variants before Omicron emerged.