The impact of physical distancing measures against COVID-19 transmission on contacts and mixing patterns in the Netherlands: repeated cross-sectional surveys in 2016/2017, April 2020 and June 2020

Abstract

AbstractBackgroundDuring the current COVID-19 pandemic many countries have taken drastic measures to reduce the transmission of SARS-CoV-2. These often include decreasing the number of contacts by physical distancing.AimTo measure the actual reduction of contacts when physical distancing measures are implemented.MethodsIn the Netherlands, a cross-sectional survey was carried out in 2016/2017 in which participants reported the number and age of their contacts during the previous day. The survey was repeated among a subsample of the participants in April 2020 after physical distancing measures had been implemented, and in an extended sample in June 2020 after some of these measures were relaxed.ResultsThe average number of community contacts per day was reduced from on average 14.9 (interquartile range: 4-20) in the 2016/2017 survey to 3.5 (0-4) after physical distancing measures were implemented, and rebounded to 8.8 (1-10) after some of these measures were relaxed. All age groups restricted their number of community contacts to at most 5 contacts on average after physical distancing measures were implemented. After relaxation, children reverted to baseline levels while elderly had a number of community contacts that was less than half their baseline levels.ConclusionThe physical distancing measures have greatly reduced contact numbers, which has likely been beneficial in curbing the first wave of the COVID-19 epidemic in the Netherlands. Different age groups reacted differently upon relaxation of these measures. These findings offer guidance for the deployment of age-targeted measures in the future course of the pandemic.