Assessing the interactions between COVID-19 and influenza in the United States

Casey M Zipfel; Shweta Bansal

In December 2019, a cluster of pneumonia cases caused by a novel coronavirus were identified in Wuhan, China. In the months since, the now-termed COVID-19 pandemic has rapidly spread around the world, leading to hundreds of thousands of cases in over 160 countries [1] . The first evidence of community spread of SARS-Cov-2, the virus which causes COVID-19, in the United States appeared in February 2020. Since then, there have been widespread workplace, school, and business closures to dampen transmission [2] . Preceding this widespread policy response, individuals, informed by massive media coverage, engaged in voluntary behaviors such as increased handwashing and social distancing [3] . Such non-pharmaceutical interventions (NPIs) are known 1 to play a significant role in diminishing transmission, and are expected to be particularly important against SARS-Cov-2 as the virus appears to transmit for up to two weeks before symptoms appear [4] . Indeed, NPIs have been very e↵ective in reducing the potential number of COVID-19 cases in China [5, 6] . As the COVID-19 outbreak unfolds, it is important to empirically understand the e↵ects of NPIs on infection spread, and characterize the potential interaction between COVID-19 and other circulating respiratory infections. As the spread of COVID-19 in the United States has been temporally coincidental with the influenza season, and both infections share the same transmission pathways and NPIs, we focus on influenza as a case study.