Quantifying interpersonal contact in the United States during the spread of COVID-19: first results from the Berkeley Interpersonal Contact Study

Dennis Feehan; Ayesha Mahmud

The SARS-COV-2 virus that can cause COVID-19 is spread by close interpersonal contact. Nonpharmaceutical interventions that reduce transmission by restricting interpersonal contact -like closing schools and banning public gatherings -are among the only options currently available to countries to slow the exponential growth of the epidemic. With the sharp increase in cases globally, many countries have adopted these "social distancing" practices at an unprecedented scale. In the US, on March 16, 2020 seven counties in the San Francisco Bay Area ordered residents to shelter in place in response to evidence of community transmission of COVID-19. Over the subsequent days and weeks, other cities and states followed suit. By the start of April 2020, the majority of people living in the United States were under orders to dramatically restrict their daily activities (Mervosh, Lu, and Swales 2020) .