Seroprevalence of SARS-CoV-2 antibodies in Bali Province: Indonesia shows underdetection of COVID-19 cases by routine surveillance.

The international tourist destination of Bali reported its first case of Coronavirus Disease 2019 or COVID-19 in March 2020. To better understand the extent of exposure of Bali's 4.3 million inhabitants to the COVID-19 virus, we performed two repeated cross-sectional serosurveys stratified by urban and rural areas. We used a highly specific multiplex assay that detects antibodies to three different viral antigens. We also assessed demographic and social risk factors and history of symptoms. Our results show that the virus was widespread in Bali by late 2020, with 16.73% (95% CI 12.22-21.12) of the population having been infected by that time. We saw no differences in seroprevalence between urban and rural areas, possibly due to extensive population mixing, and similar levels of seroprevalence by gender and among age groups, except for lower seroprevalence in the very young. We observed no difference in seroprevalence between our two closely spaced surveys. Individuals reporting symptoms in the past six months were about twice as likely to be seropositive as those not reporting symptoms. Based upon official statistics for laboratory diagnosed cases for the six months prior to the survey, we estimate that for every reported case an additional 52 cases, at least, were undetected. Our results support the hypothesis that by late 2020 the virus was widespread in Bali, but largely undetected by surveillance.

The geographic distribution of retail tobacco outlets in Yogyakarta, Indonesia.

INTRODUCTION: Tobacco smoking prevalence in Indonesia is among the highest in the world. Research worldwide identifies that physical access to tobacco through retail outlets is related to increased tobacco smoking. Tobacco outlet density is very high in many Indonesian cities, so tobacco access may contribute to the high prevalence of tobacco use in that country. The aim of this study was to examine distributions of tobacco outlets in one Indonesian city, Yogyakarta, in relation to social and physical environmental conditions. METHODS: For this cross-sectional ecological study, we virtually audited randomly selected street segments (n = 1099) using Google Street View. The outcome of interest was a count of tobacco advertising banners (indicating the presence of retail outlets). Exposures were physical environmental conditions (scales of main roads, physical decay, presence of schools, mosques, churches) and social conditions measured at the neighbourhood level (concentrated disadvantage, age composition, population density). RESULTS: Tobacco banners were present on 36.4% of sampled street segments, including 55 (37%) of 147 streets with schools; a total of 1381 banners were identified. Multilevel negative binomial regression models for street segments nested within neighbourhoods found the prevalence of tobacco banners per 100 m was lower near schools (RR = 0.66, 95% CI 0.45, 0.97) and was not associated with other exposure measures. DISCUSSION AND CONCLUSIONS: Retail tobacco outlets are ubiquitous in Yogyakarta. Although they are relatively less prevalent on streets with schools, the high absolute values and wide spatial distribution means all residents of Yogyakarta are exposed to tobacco outlets.

Cigarette retailer density around schools and neighbourhoods in Bali, Indonesia: A GIS mapping.

INTRODUCTION: The presence and density of tobacco retailers is associated with the perception of high availability of cigarettes and ease of purchase. Indonesia is the second largest cigarette market in the world with an increasing smoking rate among young people aged 10-18 years. Our study aims to assess density of cigarette outlets in neighbourhoods and around schools, and to evaluate correlation between retailer proximity to schools and retailer selling practices. METHODS: We conducted a geographical mapping and then an audit survey of 1000 randomly selected cigarette retailers in Denpasar, Bali, Indonesia. We measured neighbourhood retailer density, and retailer proximity to schools. We linked the coordinate data to the audit data to assess the association between retailer distance from schools with likelihood of selling tobacco to young people and selling single cigarette sticks. RESULTS: We mapped 4114 cigarette retailers in Denpasar, the most common type was a kiosk, 3199 (77.8%), followed by mini market/convenience stores, 606 (14.7%). Retailer density was 32.2/km2 and 4.6/1000 population. We found that 37 (9.7 %) of the 379 schools in Denpasar have at least one cigarette retailer within a 25 m radius and 367 (96.8%) within a 250 m radius. Of the 485 audited retailers within a 250 m radius of a school, 281 (57.9%) admitted selling cigarettes to young people and 325 (67.0%) sold cigarettes as single sticks. Cigarette retailers were less likely to sell cigarettes to young people based on distance from schools, but this was only significant at the furthest distance of more than 500 m from schools. CONCLUSIONS: In an unregulated retailer setting such as Indonesia, cigarette retailers are ubiquitous and selling to young people is commonplace. The Indonesian government should enforce the prohibition on selling to young people and should regulate cigarette retailers to reduce youth access to cigarettes.