An investigation of a measles outbreak in Japan and Taiwan, China, March–May 2018

Abstract

ObjectiveTo investigate a measles outbreak that spread to Japan and China, Taiwan, China during March–May 2018, exploring the characteristics of the super-spreading event.MethodsA contact investigation of the index case and reconstruction of the epidemiological dynamics of measles transmission were conducted. Employing a mathematical model, the effective reproduction number was estimated for each generation of cases.Results and discussionA single index case gave rise to a total of 38 secondary cases, 33 in Japan and five in China, Taiwan, China. Subsequent chains of transmission were observed in highly vaccinated populations in both Japan and China, Taiwan, China. The effective reproduction number of the second generation was > 1 for both Japan and China, Taiwan, China. In Japan, the reproduction number was estimated to be < 1 during the third generation. Vaccination of susceptible individuals is essential to prevent secondary and tertiary transmission events.

A Survey of Vaccine-Induced Measles IgG Antibody Titer to Verify Temporal Changes in Response to Measles Vaccination in Young Adults

“…According to a World Health Organization (WHO) announcement, Japan has achieved measles elimination, which was defined as an interruption of endemic measles virus transmission for at least 36 months [17]. Nevertheless, measles cases from foreigners in Japan have occurred sporadically [2,18,19,20,21]. Based on our surveillance, one of the causes for sporadic measles occurrence may be non-persistent protection by measles IgG antibody titers in young adults.…”

A survey of vaccine-induced measles IgG antibody titer and the verification of changes in temporal differences of measles vaccination in young adults

“…According to WHO announcement, Japan was verified as having achieved measles elimination that was defined as interruption of endemic measles virus transmission for at least 36 months [8]. Nevertheless, measles cases from foreigners in Japan have occurred sporadically [1, 9-12]. Based on our surveillance, one of the causes may be non-persistent protection by measles IgG antibody titer in young adults.…”

Identifying geographic areas at risk of rubella epidemics in Japan using seroepidemiological data

“…Because of the increasing number of foreign visitors, mainly from the Asian continent, the risk of imported infectious diseases, in general, has increased (Yuan and Nishiura, 2018;Yuan et al, 2019). Therefore, Japan is repeating experiments to test herd immunity using various vaccine-preventable imported diseases (e.g., measles), which have mostly resulted in a sporadic or small number of secondary transmissions, but sometimes resulting in a large cluster of cases (Nishiura et al, 2017;Shimizu et al, 2018).…”

“…Because of the increasing number of foreign visitors, mainly from the Asian continent, the risk of imported infectious diseases, in general, has increased ( Yuan and Nishiura, 2018 , Yuan et al, 2019 ). Therefore, Japan is repeating experiments to test herd immunity using various vaccine-preventable imported diseases (e.g., measles), which have mostly resulted in a sporadic or small number of secondary transmissions, but sometimes resulting in a large cluster of cases ( Nishiura et al, 2016 , Shimizu et al, 2018 ). The government of Japan aimed to verify the elimination of rubella by 2020, when, before the outbreak of coronavirus disease 2019 (COVID-19), the country was planning to host the Summer Olympic Games ( Jindai et al, 2018 ); ironically, however, without good herd immunity, repeated introductions can cause continued transmission, and welcoming in more visitors increases the risk of an outbreak ( Nishiura et al, 2019 ).…”