Social contacts surveys are performed in multiple time points during the pandemic. Participants report the total number of contacts that they had on the day before the survey. The first survey was implemented in March-April 2020; in that survey, social contacts data were collected for the period before the pandemic as well.
A contact is defined as either a skin-to-skin contact or a two-way conversation with three or more words in the physical presence of another person. For each contact, information on the age of the person and location this contact took place (home, school, workplace, transportation, leisure, other) is recorded.
The first results appear in Sypsa et al, Emerging Infectious Diseases 2021