Social Contact Patterns and Transmission

Close-contact infections spread along the everyday contacts people have, so who meets whom, and how often, sets the basic reproduction number R0. The evidence here comes from contact-diary surveys in Belgium and eight European countries and from a Nicaraguan paediatric cohort that estimated R for Zika.

Models used to plan school closures and vaccination depend on measured contact matrices, not guesses. Knowing what these surveys actually show helps students judge claims about how much closing schools would slow an epidemic.

Claim ledger

What the evidence shows

Drawn from 3 studies in this library. Mix labels say which citation roles are present; they are not a strength score. Supports means evidence for a finding; Challenges means evidence against a stated position; Qualifies marks scope.

• ○ Limited citations

  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.

  1 study
  1. 1Who meets whom, and how would closing schools slow an epidemic?

• ○ Limited citations

  School and work days drive contact volume.

  Across eight European countries (7,290 participants), people reported about 30% fewer contacts at weekends and about 9% fewer during holidays than on regular weekdays.

  1 study
  1. 1How much could closing schools slow a close-contact epidemic?

• ● Supporting studies only

  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).

  2 studies
  1. 1How much could closing schools slow a close-contact epidemic?
  2. 2Who meets whom, and how would closing schools slow an epidemic?

  Study comparison

  Study	Role	Design	N	Population	Outcome
  How much could closing schools slow a close-contact epidemic?2009	Supports	Cross-sectionalSecondary analysis of a one-day social contact diary survey; weighted negative binomial regression of contact counts and age-structured contact matrices used to compute relative changes in the basic reproduction number.	N=7290 · 7290 participants recording 97904 contacts on one day each; holiday comparisons were possible only for Belgium, Great Britain, Luxembourg and the Netherlands.	Broadly representative samples of all ages (children and adolescents deliberately oversampled) in Belgium, Great Britain, Finland, Germany, Italy, Luxembourg, Poland and the Netherlands, 2005-2006.	Number of daily conversational and physical contacts, age-by-age contact matrices, and the relative change in R0 for weekends versus the week and holidays versus regular periods.
  Who meets whom, and how would closing schools slow an epidemic?2009	Supports	Cross-sectionalPopulation 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=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.	A telephone-recruited sample of Belgian residents of all ages, stratified by age and region (Flanders, Wallonia, Brussels), surveyed in spring 2006.	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.

• ○ Limited citations

  Susceptibility to infection and to disease are different quantities.

  Pre-existing immunity can change the clinical picture without changing transmission: in 3,027 Nicaraguan children, prior dengue did not alter the risk of Zika infection (IRR 0.98) but lowered the chance of symptoms (IRR 0.62), and the early reproduction number was about 3.3-3.4.

  1 study
  1. 1Does an earlier dengue infection protect children from Zika?

Debates

Tensions and limits

Some items are genuine disagreements on the same question. Others mark different assays, populations, or outcomes.

Timeline

How understanding moved

Study years are when the paper was published. Evidence edits are dated changes to this page's claims. Explanations are when PaperFren added a Discovery — not a claim that the science happened that day.

Papers

3 studies in this library bear on Social Contact Patterns and Transmission, ordered by citations.

• How much could closing schools slow a close-contact epidemic?

  People had fewer and differently mixed contacts at weekends and during school holidays, which would lower an infection's reproduction number enough to suggest school closure could meaningfully slow spread in most countries studied.

  BMC infectious diseases · 2009 · 170 citations

• Does an earlier dengue infection protect children from Zika?

  Children who had caught dengue before were no less likely to be infected by Zika, but when infected they were about a third less likely to get sick with symptoms.

  PLoS medicine · 2019 · 139 citations

• Who meets whom, and how would closing schools slow an epidemic?

  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.

  BMC infectious diseases · 2009 · 83 citations

Questions

What is still open

1. 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.

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2. 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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