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Assessing the transmission dynamics of measles in Japan, 2016
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| Title: | Assessing the transmission dynamics of measles in Japan, 2016 |
| Authors: | Nishiura, Hiroshi Browse this author →KAKEN DB | | Mizumoto, Kenji Browse this author | | Asai, Yusuke Browse this author |
| Keywords: | Epidemic | | Transmissibility | | Paramyxoviridae | | Mathematical model | | Statistical estimation | | Japan |
| Issue Date: | Sep-2017 |
| Publisher: | Elsevier |
| Journal Title: | Epidemics |
| Volume: | 20 |
| Start Page: | 67 |
| End Page: | 72 |
| Publisher DOI: | 10.1016/j.epidem.2017.03.005 |
| PMID: | 28359662 |
| Abstract: | Objectives: Despite the verification of measles elimination, Japan experienced multiple generations of measles transmission following importation events in 2016. The purpose of the present study was to analyze the transmission dynamics of measles in Japan, 2016, estimating the transmission potential in the partially vaccinated population. Methods: All diagnosed measles cases were notified to the government, and the present study analyzed two pieces of datasets independently, i.e., the transmission tree of the largest outbreak in Osaka (n = 49) and the final size distribution of all importation events (n = 23 events). Branching process model was employed to estimate the effective reproduction number Rv, and the analysis of transmission tree in Osaka enabled us to account for the timing of introducing contact tracing and case isolation. Results: Employing a negative binomial distribution for the offspring distribution, the model with time dependent decline in Rv due to interventions appeared to best fit to the transmission tree data with Rv of 9.20 (95% CI (confidence interval): 2.08, 150.68) and the dispersion parameter 0.32 (95% CI: 0.07, 1.17) before interventions were introduced. The relative transmissibility in the presence of interventions from week 34 was estimated at 0.005. Analyzing the final size distribution, models for subcritical and supercritical processes fitted equally well to the observed data, and the estimated reproduction number from both models did not exclude the possibility that Rv >1. Conclusions: Our results likely reflect the highly contagious nature of measles, indicating that Japan is at risk of observing multiple generations of measles transmission given imported cases. Considering that importation events may continue in the future, supplementary vaccination of adults needs to be considered. |
| Rights: | http://creativecommons.org/licenses/by-nc-nd/4.0/ |
| Type: | article |
| URI: | http://hdl.handle.net/2115/67993 |
| Appears in Collections: | 医学院・医学研究院 (Graduate School of Medicine / Faculty of Medicine) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)
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Submitter: 西浦 博
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