
Hiroaki MurayamaSchool of Medicine, International University of Health and Welfare, Japan · Department of Medicine
Hiroaki Murayama
Working on infectious disease epidemiology: modelling infectious disease dynamics, natural history, and control.
About
18
Publications
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Introduction
Working on theoretical epidemiology and infectious disease epidemiology: mathematical modelling of infectious disease dynamics, natural history, and control.
Publications
Publications (18)
The outbreak of monkeypox across non-endemic regions confirmed in May 2022 shows epidemiological features distinct from previously imported outbreaks, most notably its observed growth and predominance amongst men who have sex with men (MSM). We use a transmission model fitted to empirical sexual partnership data to show that the heavy-tailed sexual...
Many countries affected by the global outbreak of mpox in 2022 have observed a decline in cases. Our mathematical model accounting for heavy-tailed sexual partnership distributions suggests that mpox epidemics can hit the infection-derived herd immunity threshold and begin to decline with less than 1% of sexually active MSM population infected rega...
Background:
During the 2022 global mpox outbreak, the cumulative number of countries reporting their first imported case quickly rose in the early phase, but the importation rate subsequently slowed down, leaving many countries reporting no cases by the 2022 year-end.
Methods:
We developed a mathematical model of international dissemination of m...
Initial investigation into the emerging mpox outbreak of novel clade Ib in eastern Democratic Republic of the Congo has identified signs of sustained human-to-human transmission and epidemiological links to sexual contacts involving female sex workers (FSWs), which have not been observed in previous clade Ia outbreaks. Using mathematical models inc...
Background
Declining cross-protection from historical smallpox vaccination campaigns and persistent zoonotic reservoirs leave many sub-Saharan countries susceptible to mpox outbreaks. With millions of vaccine doses made available to the region since late 2024, estimating the country specific impact of one-time mass vaccination strategies is crucial...
Introduction:
In August 2024, the World Health Organization (WHO) declared a public health emergency due to the rapid spread of mpox in African and beyond. International travel controls (ITCs), such as health screening and viral testing, could help avoid/delay the global spread of the monkeypox virus (MPXV), fostering preparedness and response effo...
The global mpox outbreak affected many Asian countries in 2023, following a sustained local transmission in Japan. Given the large population sizes and limited vaccine rollout in Asia, the potential risk of global mpox reemergence arising from Asia is of concern. Using a mathematical model incorporating heterogeneous sexual networks among MSM, cali...
Mathematical models for sexually transmitted infections (STIs) are parameterised by empirical data on sexual behaviour (e.g. the number of partners over a given period) obtained from surveys. However, the time window for reporting sexual partnerships may vary between surveys and how data for different windows can be translated from one to another r...
Background
The 2022 global mpox outbreak spread rapidly, primarily among men who have sex with men in Western countries. The number of countries with new mpox importation events quickly rose in the early phase of the outbreak, but the rate of increase subsequently slowed down, having many countries without any reported cases.
Methods
We developed a...
Many countries affected by the global outbreak of monkeypox in 2022 have observed a decline in cases. Our mathematical model incorporating empirical estimates of the heavy-tailed sexual partnership distribution among men who have sex with men (MSM) suggests that monkeypox epidemics can hit the infection-derived herd immunity threshold and begin to...
Monitoring time-varying vaccine effectiveness (e.g., due to waning of immunity and the emergence of novel variants) provides crucial information for outbreak control. Existing studies of time-varying vaccine effectiveness have used individual-level data, most importantly dates of vaccination and variant classification, which are often not available...
COVID-19 vaccine effectiveness against death in Japan remains unknown. Furthermore, although evidence indicates that healthcare capacity influences case-fatality risk (CFR), it remains unknown whether this relationship is mediated by age. With a modeling study, we analyzed daily COVID-19 cases and deaths during January–August 2021 by using Tokyo su...
A global outbreak of monkeypox across non-endemic regions including Europe and North America was confirmed in May 2022. The current outbreak has shown distinct epidemiological features compared with past outbreaks in non-endemic settings, most notably its observed rapid growth and predominant spread among men who have sex with men (MSM). We use a b...
Assessing the impact of temperature on COVID-19 epidemiology is critical for implementing non-pharmaceutical interventions. However, few studies have accounted for the nature of contagious diseases, i.e., their dependent happenings. We aimed to quantify the impact of temperature on the transmissibility and virulence of COVID-19 in Tokyo, Japan, emp...
Background
In Japan, a part of confirmed patients’ samples have been screened for the variant of concern (VOC), including the variant alpha with N501Y mutation. The present study aimed to estimate the actual number of cases with variant alpha and reconstruct the epidemiological dynamics.
Methods
The number of cases with variant alpha out of all PC...