evidence: Many of the reported symptoms were consistent with systemic inflammation, including fatigue, myalgias, chills, fever and joint pain being report in the range of 25.6% to 53.9% of individuals the day following their 2nd dose13. The rate of systemic symptoms following a booster dose are slightly less, in general, than after a second dose, but greater than after a first dose14. The relationship between reactogenicity symptoms after vaccination and immune response is controversial15, although one study of a COVID-19 vaccine identified a direct correlation between the duration of time between a first and second vaccine dose, reactogenicity and eventual humoral immune response16. In addition, a recent study found a significant relationship between individual changes in physiologic parameters measured using a smart ring and ~30 day antibody levels17.