- aBased on school contacts who shared (class) rooms for at least two course hours in the recent 14 days
- bDay 0 is set at the date of the first sample for each subject. Some sampling rounds were spread over 2 days, therefore days between exposure to index and first sample may vary per subject
- cDefined as infections in household members detected after day 0
- dA household member of this case tested positive in the 2 weeks before study initiation
- eNo symptom data available
- fHousehold member tested positive but within 24 h after the student’s result