Figure 2.

Self-reported reactions and physiological reactions to the second booster dose compared with the first booster dose

Reactions to the second booster, as recorded by the smartwatches (A, B). The figures show the mean difference between the baseline period and period after vaccination for heart rate (n=570; A) and heart rate variability-based stress (n=567; B). Mean values are depicted as solid lines and 95% CIs are presented as shaded regions. Boxplots of the differences between the daily mean changes in the smartwatch indicators for heart rate (n=363; C) and heart rate variability-based stress (n=358; D) between the second and first booster. Each change is between the period after vaccination and the baseline periods. Each green dot represents a single participant. (E) A comparison of the reactions reported by participants between the first and second boosters (n=392). The bars represent the percentage of participants who reported a reaction. Error bars represent 95% CIs. For each panel, the sample size represents the number of participants that we had sufficient data points to conduct the analysis using the criteria presented in the methods section.