Features of the studies identified
| Number of studies | |
|---|---|
| Total studies | 79 |
| Type of outbreak | |
| Seasonal | 22 |
| 1918 pandemic | 7 |
| 1968 pandemic | 1 |
| 2009 pandemic | 49 |
| Setting | |
| Europe | 22 |
| North America | 22 |
| Central America | 5 |
| South America | 3 |
| Asia | 20 |
| Africa | 1 |
| Australasia | 6 |
| Data provided on* | |
| Children only | 25 |
| General population | 29 |
| School pupils and staff | 5 |
| Children and other specified groups separately | 22 |
| Reason for closure | |
| High student absenteeism | 3 |
| High staff absenteeism | 1 |
| High student and staff absenteeism | 1 |
| Other reactive closure† | 31 |
| Proactive | 7 |
| Planned holiday | 38 |
| Other‡ | 3 |
| Unclear | 3 |
| Period of closure | |
| Continuous | 67 |
| Intermittent | 8 |
| Variable§ | 3 |
| Not stated | 1 |
| Other interventions in place¶ | |
| None | 20 |
| Antivirals | 33 |
| Other social distancing | 24 |
| Vaccination | 8 |
| Other | 20 |
| Timing of closure | |
| Before peak | 21 |
| Same day/week as peak | 9 |
| After peak | 36 |
| Variable§ | 8 |
| Unclear | 8 |
| Duration of closure** | |
| <7 days | 8 |
| 7–13 days | 33 |
| 14–20 days | 19 |
| ≥21 days | 17 |
| Variable§ | 6 |
| Not stated | 2 |
Studies may present more than one dataset and so appear in more than one row of each section.
*Each study may present more than one data source.
†Closure in response to outbreak, not stated as being for operational reasons.
‡Teachers’ strike (2 studies) or response to SARS outbreak (1 study).
§Studies of multiple US cities during the 1918 pandemic or multiple countries in 2009.
¶Described in the included paper or related papers; excludes normal levels of vaccine and antiviral usage in seasonal datasets.
**Each study may present more than one dataset for which the durations of closure differed.