Explaining the Bomb-Like Dynamics of COVID-19 with Modeling and the Implications for Policy

Gary Lin; Alexandra T Strauss; Maxwell Pinz; Diego A Martinez; Katie K Tseng; Emily Schueller; Oliver Gatalo; Yupeng Yang; Simon A Levin; Eili Y Klein

Assuming a large fraction of the population is asymptomatically infected has important implications for policy because of herd immunity. While there have been some potential second cases, the vast majority of the evidence suggests that infected individuals develop immunity to circulating strains. As more of the population gains immunity, disease spread will slow. When transmissibility between contacts falls because of widespread immunity, the effective reproductive number is reduced, the disease spreads more slowly, and the threat posed by widespread numbers of infected individuals fades away. Such widespread immunity would allow restrictions to be lifted sooner, as most individuals would not pose a transmission risk to the general public and would abrogate the possibility of a second peak in the future. Understanding the potential risks requires serological surveys to be conducted as soon as possible in areas with high and low numbers of cases to understand how much the disease has been spreading and to inform better policies regarding quarantines.