Measles and rubella immunity in the population of Bhutan, 2017.

BACKGROUND: In 2017, measles elimination was verified in Bhutan, and the country appears to have sufficiently high vaccination coverage to achieve rubella elimination. However, a measles and rubella serosurvey was conducted to find if any hidden immunity gaps existed that could threaten Bhutan's elimination status. METHODS: A nationwide, three-stage, cluster seroprevalence survey was conducted among individuals aged 1-4, 5-17, and >20 years in 2017. Demographic information and children's vaccination history were collected, and a blood specimen was drawn. Serum was tested for measles and rubella immunoglobulin G (IgG). Frequencies, weighted proportions, and prevalence ratios for measles and rubella seropositivity were calculated by demographic and vaccination history, taking into account the study design. RESULTS: Of the 1325 individuals tested, 1045 (81%, 95% CI 78%-85%) were measles IgG seropositive, and 1290 (97%, 95% CI 95%-99%) were rubella IgG seropositive. Rubella IgG seropositivity was high in all three age strata, but only 47% of those aged 5-17 years were measles IgG seropositive. Additionally, only 41% of those aged 5-17 years who had documented receipt of two doses of measles- or measles-rubella-containing vaccine were seropositive for measles IgG, but almost all these children were rubella IgG seropositive. CONCLUSIONS: An unexpected measles immunity gap was identified among children 5-17 years of age. It is unclear why this immunity gap exists; however, it could have led to a large outbreak and threatened sustaining of measles elimination in Bhutan. Based on this finding, a mass vaccination campaign was conducted to close the immunity gap.

Twenty-two years of HIV infection in Bhutan: epidemiological profile.

AIMS: To describe the HIV epidemiology in Bhutan. METHODS: Data from the database of people living with HIV infection in Bhutan, survey reports from the National STI and HIV/AIDS Control Programme from the Ministry of Health and published literature on HIV in Bhutan were reviewed. RESULTS: Bhutan continues to have a low HIV prevalence with only 470 cases reported by the end of 2015. However, there is a slow but steady recent increase in the number of cases. The main mode of transmission is unsafe heterosexual practice in the general population and is occurring mostly in urban and business districts. More than half of cases have been diagnosed in only three districts. Although the number of cases among key populations such as sex workers and intravenous drug users remains significantly low, the information available remains very limited. There is only scarce published literature on HIV in Bhutan and an absence of a strategic surveillance system. A high level of sexually transmitted infections and multiple sexual relationships represent the existing threats that may fuel a larger epidemic. CONCLUSIONS: Bhutan has a maintained a low HIV prevalence over the past two decades, which is reflected in the national response to HIV. However, with the presence of existing and newly emerging risk factors, this response needs to adapt continually. To ensure that HIV prevalence remains low, it is crucial to invest in a strategic information system to monitor rates of infections to guide the public health response.