*refers to the end of the person-time included in the analysis for each
participant. The person-time ended on: 1) the day of the first
infection, 2) the day of receipt of a third vaccine dose, 3) the day of
receipt of a second vaccine dose if the interval between first and
second dose is shorter than the manufacturer recommendation, 4) the day
of the last weekly questionnaire before complete loss to follow-up,
withdrawal or censor date, or the last weekly questionnaire before 1 Dec
2021.
**chronic conditions include: cancer, chronic heart disease, high blood
pressure/hypertension, chronic kidney disease, chronic liver disease
(such as cirrhosis, hepatitis, fatty liver disease), chronic lung
disease (such as asthma, COPD), diabetes, immunocompromised (including
solid organ transplant and HIV), neurologic disease (including
cerebrovascular disease, epilepsy, multiple sclerosis), obesity,
autoimmune disorder