Study of patterns of social contacts early on in COVID-19 pandemic


The coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has compelled people worldwide to quarantine. To mitigate the transmission of SARS-CoV-2, countries and workplaces have been under varying stages of lockdown since the detection of the infection in December 2019 in Wuhan, China.

In mid-April 2020, it was observed that 62% of employed adults were working remotely in response to the COVID-19 pandemic. This scenario is continuing, and there is no standardized multi-site social contact study conducted in workplace settings. A study of this order helps plan strategies to address the pandemic situation – before onset as well as during.

16% of influenza transmission is estimated to occur in the workplace setting due to social interactions and respiratory infection transmissions. Likewise, the conditions at the workplace determine the SARS-CoV-2 transmission percentage.

Any significant impact of remote work on COVID-19 needs to be evaluated; this can be achieved by assessing changes in social contact patterns. In this context, Moses C. Kiti et al. published a recent medRxiv* preprint paper studying social contact patterns. In this study, they characterized the mixing across workplace environments, including on-site or when teleworking.

The median number of contacts per person per day was found to be two contacts per respondent. The authors stratified this information by day of data collection, age, sex, race, and ethnicity. This information can be broadly employed in pandemic preparedness policy for similar settings.

This study involved two multinational consulting companies ((N1=275, N2=3000) and one university administrative department ((N3=560), located in Atlanta, Georgia, USA, from April to June 2020, when the shelter-in-place orders were in effect. The employees opted into the study by accepting an email invitation. Remote working was defined as any working location (home or public space) outside their designated workplace. Employees approached were 3,835, out of which 357 (9.3%) responded on the first day of contact, and 304 completed both days of contact. The results are summarized from those respondents who completed the dairy on both days.

This study was a cross-sectional non-probability survey that used standardized social contact diaries into which the respondents were to fill in. The respondents recorded their physical and non-physical contacts over two days, documented at the end of each day.

Panel (A) shows the distribution of contacts by attributes: duration (in minutes (mins) or hours (hr)). Types of contact were conversation with physical touch (Conv & Phys), physical only (Phys), or non-physical/conversation only (Conv only). A contact was repeated if observed on both days or unique if observed on only one day. Panel (B) shows the age-stratified average number of contacts over two study days. The gray area on the x-axis indicates that all respondents were over the age of 19, however they were able to report contacts under the age of 19 years. Data shown in the graphs are for 1,548 contacts recorded by 304 participants over 608 diary-days

A median of 2 contacts per respondent on both day one and two were observed.

Most of the contacts (55%) involved conversation only – occurred at home (64%) and cumulatively lasted more than 4 hours (38%). Most contacts were repeated and within the same age groups. Participants aged 30-59 years, however, reported inter-generational mixing with children.

This study compares to similar reports from the UK and China, effective during the shelter-in-place orders in the pandemic. Pre-pandemic data is unavailable for direct comparison. While the median contact number is 2, many of the contacts were repeated, which may limit the spread of infection.

Mathematical models are used to forecast and simulate the effects of interventions implemented during pandemics. These models are highly sensitive to assumptions about how people acquire infection and how they transmit it to others.

The data on the social contact patterns – the frequency and nature of contacts that individuals make daily – determine these assumptions. The authors discuss a few selection and information biases that may be present in this study.

The authors propose similar studies to assess the changes in contact patterns to parameterize mathematical models describing disease transmission and post-lockdown due to the COVID-19 pandemic. Such studies help reduce the transmission risks, investigate prevention methods, and mitigate infection in the workplace.

*Important Notice

medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.

Journal reference:

  • Social contact patterns among employees in 3 U.S. companies during early phases of the COVID-19 pandemic, April to June 2020. Moses Chapa Kiti, Obianuju G Aguolu, Carol Liu, Ana Mesa Restrepo, Rachel Regina, Kathryn Willebrand, Chandra Couzens, Tilman Bartelsmeyer, Kristin Nicole Bratton, Samuel M Jenness, Steven Riley, Alessia Melegaro, Faruque Ahmed, Fauzia Malik, Ben Lopman, Saad B Omer medRxiv 2020.10.14.20212423; doi: https://doi.org/10.1101/2020.10.14.20212423, https://www.medrxiv.org/content/10.1101/2020.10.14.20212423v1  



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