Figure 3.

Changes in objective physiologic indicators measured through smartwatch for self-reported and physiologic reactions to BNT162b2 (Pfizer, https://www.pfizer.com) mRNA coronavirus disease vaccine doses. Mean difference are shown for smartwatch-recorded heart rate (A‒C), HRV-based stress (D‒F), and SpO₂ (G‒I) after the first, second, and third dose compared with their baseline levels. Mean values are indicated by solid lines; 90% CIs are indicated as shaded regions. Horizontal dashed line indicates no change compared with baseline levels, and vertical lines indicate 24-hour periods. HRV, heart-related variability; SpO₂, blood oxygen saturation level.