Infectious disease
Who meets whom, and how would closing schools slow an epidemic?
Open access · cc by · source: Europe PMC
Contact diaries showed that people mostly mix with others of similar age, and plugging holiday-period contacts into an epidemic model suggested that closing schools would cut the reproduction number of a flu-like infection by about a sixth.
Study at a glance
- Design
- Cross-sectional — Population contact-diary survey (one random weekday plus one random weekend day per person) recruited by random digit dialling, analysed with association rules, classification trees and weighted GEE, then used to parameterise a next-generation-matrix epidemic model.
- N
- N=750 · 750 Belgian residents (adults, teenagers and children, with parents completing diaries for young children), each recording contacts on two days; analyses are at the level of recorded contacts and participant-days.
- Population
- A telephone-recruited sample of Belgian residents of all ages, stratified by age and region (Flanders, Wallonia, Brussels), surveyed in spring 2006.
- Outcome
- Number and type of daily social contacts (conversation vs skin-to-skin touch, location, duration, frequency) and the age-by-age contact matrix; modelled change in the basic reproduction number under school-holiday and weekend mixing.
Structured fields used in claim comparison tables when every cited study has a complete layer.
Key findings
Most close contacts happened at home, and touching was most likely for long, frequent, home or leisure contacts; overall 61% of contacts involved skin-to-skin touch. Contact numbers rose with household size and class size, adults in work or study had about twice as many contacts as unemployed or retired adults, and adults living with children averaged 10.4 close contacts versus 8.2 for those without. Mixing was strongly assortative by age with a parent–child component. With the reproduction number set to 2 under normal term-time mixing, holiday-period contact patterns lowered it to 1.69 (a 15.5% reduction), while weekend-only patterns lowered it to 1.33.
Methodology
The researchers recruited 750 people living in Belgium by random telephone dialling and asked each to keep a paper diary of everyone they talked to or touched on one weekday and one weekend day. People with very many work contacts estimated those separately, and the team imputed them rather than dropping them. They mined the diaries for patterns (which contacts involve touching, where and how long), modelled what predicts how many contacts a person has, built an age-by-age contact matrix, and used it in a model of a new flu-like infection to compare normal, school-holiday and weekend mixing.
Limitations
The school-closure result is a model projection built on self-reported diaries, not an observed drop in infections, and it assumes transmission is proportional to touching contacts with a fixed five-day infectious period. Recruitment used landline phones only, which the authors note under-represents people who only have mobile phones. Very high work-contact counts had to be imputed, which changed the average number of contacts substantially, and holiday periods differ from true school closures in ways (such as grandparent childcare) that may not transfer to an emergency closure.
How this study connects
Role on claims
Each row is a claim on a concept or method page where this paper supports, challenges, or qualifies the statement. Roles are hand-checked — not a model guess.
Children mix mostly with children, and with their parents.
Mixing is strongly assortative by age, with a parent-child component, and most close contacts occur at home; in a Belgian survey of 750 people 61% of contacts involved skin-to-skin touch, and adults living with children averaged 10.4 close contacts versus 8.2.
Evidence for the claim as stated.
School holidays are a natural experiment suggesting partial, not complete, reductions.
Feeding holiday-period contact matrices into models lowered R0 by amounts that varied widely by country: 10% in Belgium, 17% in Great Britain, 45% in the Netherlands and no significant change in Luxembourg; the single-country Belgian survey estimated a 15.5% reduction (R from 2 to 1.69).
Evidence for the claim as stated.
The European surveys model contact-driven, close-contact respiratory spread; Zika is mosquito-borne, so its reproduction number reflects vector ecology rather than human mixing. The Zika cohort shows how immunity modifies outcomes, not how contact matrices apply to it.
Evidence for the claim as stated.
Holiday contact patterns are only a proxy for school closure: during real closures parents may also stop work or children may gather elsewhere, and the surveys are cross-sectional self-reports from 2005-2006.
Evidence for the claim as stated.
Open questions
Tensions this paper is part of
From concept pages' “where studies disagree.” Disagreement means the same question; scope means different assays, populations, or outcomes.
The European surveys model contact-driven, close-contact respiratory spread; Zika is mosquito-borne, so its reproduction number reflects vector ecology rather than human mixing. The Zika cohort shows how immunity modifies outcomes, not how contact matrices apply to it.
Holiday contact patterns are only a proxy for school closure: during real closures parents may also stop work or children may gather elsewhere, and the surveys are cross-sectional self-reports from 2005-2006.
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