In Phase 1 of the American Heart Association COVID-19 Data Challenge our team reported results from our report entitled, “Effect of Public Health Policies on New Confirmed Cases for Coronavirus Disease 2019 in South Korea: Lessons for the World.”

In Phase 2, we introduce 2 separate analyses that build on this work by evaluating the impact of the COVID-19 pandemic on key population groups in the United States. In Part I of Phase 2, we examine how policies related to university and college reopening affected new confirmed COVID-19 cases in surrounding communities leveraging several publicly available data sources. In Part II of Phase 2, we leverage IBM Marketscan Data that were made available to teams as part of the AHA COVID-19 Data Challenge to estimate the number of individuals at high-risk for infection within the general population. Addressing these questions together will allow policymakers and public health officials to consider both the immediate and long-term impact of the COVID-19 pandemic as the U.S. and world brace for additional waves of infection during the upcoming winter.

Main findings:

  • The number of university and college students returning to campus had a positive association with new confirmed COVID-19 cases within the local county region where the institution resided. In comparison to holding class in-person, reopening colleges online or in a hybrid mode was associated with a lower number of new confirmed COVID-19 cases.

  • The number of individuals considered at high-risk for COVID-19 infection due to age, medical conditions and an immunocompromised state (due to solid organ transplant or drug use) varies considerably across the United States. These findings may be valuable for future work that evaluates how policies for reopening businesses and other social activities may need to be tailored at the state-level if COVID-19 cases continue to grow over time.

Part I. University reopening policies and new confirmed COVID-19 cases.


The new academic year for universities and colleges in the U.S. began in the midst of the COVID-19 pandemic in late August and early September. During March and April, most schools moved their class fully online and locked down the campus. For the 2020 fall semester, many schools opted to reopen fully or partially given a desire to optimize learning environments. However, other schools chose to institute policies supporting an online or hybrid mode of learning given concerns for student safety. Though all schools have tried to take many public health actions to ensure reopening occurs safely, numerous reports in the lay media suggest universities and colleges experienced outbreaks of COVID-19 cases after students returned. As indirect evidence, the overall total number of daily new confirmed cases across the U.S. shows an increasing trend starting from early September in Figure 1 that coincides with the time of school reopenings (both universities, colleges and elementary/secondary schools).

Left: Nationwide total number of daily new confirmed COVID-19 cases since June 1st and their 7-day average. The number of daily new confirmed COVID-19 cases shows an increasing trend starting from early September that coincides with the time of school reopening. Right: The log-transformed number of total new confirmed cases from September 1st to October 22nd across 3046 U.S. counties. Counties are colored gray if the information is unavailable.