Social contact patterns among employees in 3 U.S. companies during early phases of the COVID-19 pandemic, April to June 2020


Importance Devising control strategies against diseases such as COVID-19 require understanding of contextual social mixing and contact patterns. There has been no standardized multi-site social contact study conducted in workplace settings in the United States that can be used to broadly inform pandemic preparedness policy in these settings. Objective The study aimed to characterize the patterns of social contacts and mixing across workplace environments, including on-site or when teleworking. Design This was a cross-sectional non-probability survey that used standardized social contact diaries to collect data. Employees were requested to record their physical and non-physical contacts in a diary over two consecutive days, documented at the end of each day. Employees from each company were enrolled through email and electronic diaries sent as individual links. Data were collected from April to June 2020. Setting Two multinational consulting companies and one university administrative department, all located in Georgia, USA. Participants Employees opted into the study by accepting the invitation on a link sent via email. Main Outcome The outcome was median number of contacts per person per day. This was stratified by day of data collection, age, sex, race and ethnicity. Results Of 3,835 employees approached, 357 (9.3%) completed the first day of contact diary of which 304 completed both days of contact diary. There was a median of 2 contacts (IQR: 1-4, range: 0-21) per respondent on both day one and two. The majority (55%) of contacts involved conversation only, occurred at home (64%), and cumulatively lasted more than 4 hours (38%). Most contacts were repeated, and within same age groups, though participants aged 30-59 years reported substantial inter-generational mixing with children. Conclusion Participating employees in 3 surveyed workplaces reported few contacts, similar to studies from the UK and China when shelter-in-place orders were in effect during the pandemic. Many contacts were repeated which may limit the spread of infection. Future rounds are planned to assess changes in contact patterns when employees resume work in the office after the lockdown due to COVID-19 pandemic.

MIDAS Network Members

Steven Riley

Professor of Infectious Disease Dynamics
Imperial College London