Social Contact Patterns and Age Mixing before and during COVID-19 Pandemic, Greece, January 2020-October 2021.

We collected social contact data in Greece to measure contact patterns before (January 2020) and during the COVID-19 pandemic (March 2020-October 2021) and assess the effects of social distancing over time. During lockdowns, mean daily contacts decreased to 2.8-5.9 (mean prepandemic 20.4). Persons >65 years of age retained the fewest contacts during the pandemic (2.1-4.1). Compared with the first lockdown (March-April 2020), the second lockdown (November-December 2020) and third lockdown (April 2021) showed higher numbers of contacts (incidence rate ratio 1.50 [95% CI 1.27-1.76] in second lockdown and 2.19 [95% CI 1.86-2.58] in third lockdown). In 2021, an increase in contacts was apparent, which persisted during the April 2021 lockdown among persons 18-64 years of age. Our study provides evidence of the waning observance of physical distancing. Effective risk communication alongside targeted social distancing could offer alternatives to repeated lockdowns.