Summary of harms of closing schools. Results from Belgian studies and rapid review
| Harms | Schools closed | Schools open | Certainty of evidence (GRADE) | Conclusions of reviews |
| Per 100 000 for 14 days | ||||
| Learning delay (short and long term) | Loss of 6 months | Moderate | Dutch children had a learning loss of one-fifth of a school year.18 | |
| A learning delay may cause long-term consequences, estimated on the basis of a study that evaluated long-term effects of a school strike in 1990 in Wallonia.19 | ||||
| Mental health of children | May | September | Very low | During the lockdown increased levels of distress, worry and anxiety in children and young people were reported.20 |
| % children feeling well | 57 | 82 | ||
| % children <3 GHQ-12 | 45 | 55 | ||
| Mean number of chats about anxiety, depression, suicidal thoughts | −43% | |||
| Child abuse (mean number of reports) | Low | The pandemic seems to increase the number of contacts to helplines significantly. The number of contacts related to violence is inconsistent.21 The lockdown seems to increase the number of incidents of violence against women, children and adolescents.22 | ||
| 2020 vs 2019 (March–August) | +80% | |||
| May versus September 2020 | +54% | |||
| Neglect (number of interventions due to neglect) 2020 vs 2019 | −32% | Very low | ||
| Mental health of parents | No Belgian data | |||
| Mental health of teachers | No Belgian data | |||
GHQ-12, General Health Questionnaire-12; GRADE, Grading of Recommendations Assessment, Development and Evaluation.