Effective containment explains sub-exponential growth in confirmed cases of recent COVID-19 outbreak in Mainland China

• DOI: 10.1101/2020.02.18.20024414
• Publication Date: 2020-02-20T23:25:15Z
• Authors: Benjamin F. Maier; Dirk Brockmann
• Keywords: Basic reproduction number

The recent outbreak of COVID-19 in Mainland China is characterized by a distinctive algebraic, sub-exponential increase confirmed cases with time during the early phase epidemic, contrasting an initial exponential growth expected for unconstrained sufficiently large reproduction rate. Although case counts vary significantly between affected provinces China, scaling law t μ surprisingly universal, range exponents = 2.1 ± 0.3. universality this behavior indicates that, spite social, regional, demographical, geographical, and socio-economical heterogeneities Chinese provinces, dominated fundamental mechanisms that are not captured standard epidemiological models. We show observed direct consequence containment policies effectively deplete susceptible population. To end we introduce parsimonious model captures both, quarantine symptomatic infected individuals as well population wide isolation response to mitigation or behavioral changes. For parameters, reproduces explains exponents. Quantitative fits empirical data permit identification peak times number asymptomatic oligo-symptomatic, unidentified individuals, estimates local variations basic number. implies signature effective contaiment strategies and/or systematic changes affect substantial fraction These insights may aid implementation potential export induced secondary outbreaks elsewhere similar future other emergent infectious diseases.