Abstract
The basic reproductive number (R0) is a fundamental measure used to quantify the transmission potential of an epidemic in public health practice. However, R0 cannot reflect the time-varying nature of an epidemic. A time-varying effective reproductive number Rt can provide more information because it tracks the subsequent evolution of transmission. However, since it neglects individual-level geographical variations in exposure risk, Rt may smooth out interpersonal heterogeneous transmission potential, obscure high-risk spreaders, and hence hamper the effectiveness of control measures in spatial dimension. Therefore, this study proposes a new method for quantifying spatially adjusted (time-varying) reproductive numbers that reflects spatial heterogeneity in transmission potential among individuals. This new method estimates individual-level effective reproductive numbers (Rj) and a summarized indicator for population-level time-varying reproductive number (Rt). Data from the five most severe dengue outbreaks in southern Taiwan from 1998–2015 were used to demonstrate the ability of the method to highlight early spreaders contributing to the geographic expansion of dengue transmission. Our results show spatial heterogeneity in the transmission potential of dengue among individuals and identify the spreaders with the highest Rj during the epidemic period. The results also reveal that super-spreaders are usually early spreaders that locate at the edges of the epidemic foci, which means that these cases could be the drivers of the expansion of the outbreak. Therefore, our proposed method depicts a more detailed spatial-temporal dengue transmission process and identifies the significant role of the edges of the epidemic foci, which could be weak spots in disease control and prevention.
Highlights
The basic reproductive number (R0) is a fundamental measure used to quantify the transmission potential of an epidemic in public health practice
The renewal equation estimates the values of the time-varying effective reproductive number (Rt), defined as the population-level transmission potential at time t11,13
We proposed a new method of calculating the spatially adjusted effective reproductive number by incorporating a spatial-weighting function that captures the nature of heterogeneous mixing
Summary
The basic reproductive number (R0) is a fundamental measure used to quantify the transmission potential of an epidemic in public health practice. A time-varying effective reproductive number Rt can provide more information because it tracks the subsequent evolution of transmission Since it neglects individual-level geographical variations in exposure risk, Rt may smooth out interpersonal heterogeneous transmission potential, obscure high-risk spreaders, and hamper the effectiveness of control measures in spatial dimension. This study proposes a new method for quantifying spatially adjusted (time-varying) reproductive numbers that reflects spatial heterogeneity in transmission potential among individuals. The basic reproductive number (R0) is a fundamental measure used to quantify the transmission potential of an epidemic[1] It is defined as the number of infections caused by an index case within a completely susceptible population, i.e., a population in which there is no pre-existing immunity. The renewal equation estimates the values of the time-varying effective reproductive number (Rt), defined as the population-level transmission potential at time t11,13. The effect of spatial proximity or distance should be accounted for in the estimation of effective reproductive numbers
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
