Contacts in context: large-scale setting-specific social mixing matrices from the BBC Pandemic project

Petra Klepac; Adam J Kucharski; Andrew JK Conlan; Stephen Kissler; Maria Tang; Hannah Fry; Julia R Gog

The total conversational and physical contacts varied greatly across different age groups (Fig 2A,B ). On average, participants reported over three times more conversational contacts than physical contacts, and contacts that spanned a larger age range. The very strong diagonal density of contacts ( Fig 2B) is characteristic of strong age-assortative mixing, and the sub-diagonal density captures interactions between children and their parents. The dominant eigenvectors of the matrices, which indicate the age groups that would drive transmission during the exponential phase of an epidemic simulated using these data, are highest for the 30-34 age group ( Fig 2C) . In general, eigenvectors based on physical only contacts and all contacts (both conversational and physical) are very similar except for the ages over 65 where relative dominance is higher for physical contacts.