Estimating unobserved SARS-CoV-2 infections in the United States

Alex Perkins; Sean M. Cavany; Sean M Moore; Rachel J Oidtman; Anita Lerch; Marya Poterek

Despite the advantages of our approach, there are limitations of it that should be acknowledged. First, our results were, in some cases, sensitive to deviations from baseline assumptions (Supplementary Information Text). Although most parameter scenarios we explored resulted in similar cumulative infections, higher values of R and earlier importation resulted in estimates in excess of 100,000 (Fig. S6) . Second, our branching process model assumes exponential growth, which could be affected by social distancing (24) or the buildup of immunity (25). Neither of those factors were likely to have had much influence on local transmission of SARS-CoV-2 in the US before March 13, however. Third, our parameter assumptions were based on analyses of data collected outside the US. Similar information has proven useful for other pathogens though, such as Zika and Ebola in past public health emergencies (26, 27). Fourth, we did not make use of airline data to model importation (28), but future applications of our method could incorporate that type of information.