Antimicrobial resistance deaths in the Western Pacific set to surge by 2050

Antimicrobial resistance (AMR) was associated with an estimated 1.15 million deaths across the WHO Western Pacific Region in 2021, of which 248,000 were directly attributable to drug-resistant infections, according to the most comprehensive regional assessment of the problem to date. The analysis, which spans 32 countries and territories from 1990 to 2021 and projects the burden forward to 2050, also links resistance to 29.9 million disability-adjusted life-years (DALYs) in 2021, with 6.56 million DALYs directly attributable to resistant organisms. The findings suggest the region, home to roughly 2.2 billion people or about 24 percent of the global population, contributes 21.8 percent of the 1.14 million deaths attributable to AMR worldwide and 24.4 percent of the 4.71 million deaths associated with AMR in 2021.

The study builds on the methodological framework of the 2021 global burden of AMR analysis, extending it to country-level estimates across the Western Pacific. The researchers drew on a data foundation of 520 million individual records or isolates covering 19,513 study-location-years, combining cause-of-death data, mortality surveillance, hospital discharge records, insurance claims, microbiology data, antibiotic resistance surveillance reports, pharmaceutical sales data and antibiotic usage surveys. Their modelling pipeline proceeded in nine broad steps: estimating deaths involving sepsis, allocating those deaths to infectious syndromes, linking pathogens to syndromes and deaths, modelling resistance prevalence for 84 pathogen-drug combinations, and finally quantifying excess mortality and longer hospital stays caused by resistance. Burden was calculated under two counterfactual scenarios, one replacing resistant infections with drug-susceptible ones and another replacing them with no infection at all.

The estimates reveal a striking demographic transformation in the regional AMR burden. In 1990, deaths associated with AMR in children younger than five years stood at 397,000, while deaths among people aged five and older numbered 705,000. By 2021, the picture had inverted: AMR-associated deaths in children under five had fallen by 87.3 percent to 50,400, whereas deaths among those five and older had risen by 55.4 percent to 1.1 million. Adults aged 70 years or older experienced an increase of more than 88.9 percent in associated mortality over the study period. The authors attribute this shift to declining child mortality, rapid population ageing, greater survival into older ages where vulnerability to severe infection is higher, and persistent resistance in key pathogen-drug combinations.

The leading infectious syndromes also changed over the three decades covered. In 1990, lower respiratory tract and thorax infections dominated, accounting for 1.12 million deaths, or 34.9 percent of all infectious-syndrome deaths, with roughly half of those deaths associated with resistant pathogens. By 2019 and 2021, bloodstream infections had become the leading syndrome, with 806,000 and 831,000 deaths respectively, of which around 41 percent were associated with AMR. Together with peritoneal and intra-abdominal infections and urinary tract infections, these four syndromes accounted for 92.1 percent of AMR-associated deaths in the region in 2021. The apparent stability of overall AMR deaths over recent decades, the researchers caution, should not be read as evidence that the problem has stalled; rather, as total bacterial infection mortality declined, resistant infections came to represent a growing share of the remaining fatal burden.

At the country level, China carried the largest absolute burden, with 160,000 deaths attributable to and 712,000 deaths associated with AMR in 2021, nearly two-thirds of the regional total. Yet when rates are age-standardised, a very different geography emerges. In 1990, Cambodia recorded the highest attributable mortality rate at 43.7 deaths per 100,000 population, while Australia and New Zealand had the lowest. By 2021, the Solomon Islands and Kiribati led with associated mortality rates of about 121 deaths per 100,000, and six countries exceeded 25 attributable deaths per 100,000: the Solomon Islands, Kiribati, Nauru, the Marshall Islands, Cambodia and Vanuatu. New Zealand recorded the lowest 2021 rates, at 3.2 attributable and 14.9 associated deaths per 100,000, followed by Australia, Japan, Singapore, South Korea, Guam and China.

Three pathogens dominated the regional toll in both 1990 and 2021. Streptococcus pneumoniae was the leading cause in 1990 with 329,000 associated deaths, declining to 228,000 by 2021. Staphylococcus aureus showed a marked rise, from 122,000 associated deaths in 1990 to 248,000 in 2021, making resistant S. aureus the single largest contributor to the associated pathogen burden in 2021 at 21.6 percent. Escherichia coli deaths rose from 122,000 to 165,000 over the same period. Among Gram-negative organisms, Klebsiella pneumoniae and Acinetobacter baumannii each contributed roughly 96,700 and 107,000 associated deaths in 2021, with Pseudomonas aeruginosa adding a further 92,200. Together, these six pathogens accounted for approximately 85 percent of both attributable and associated AMR mortality in the region.

The analysis of specific pathogen-drug combinations revealed considerable heterogeneity between countries. Methicillin-resistant S. aureus was the leading combination for attributable deaths in eight countries, including China, Japan, South Korea, Australia and Singapore, while carbapenem-resistant A. baumannii topped the list in 12 countries, particularly across several Pacific Island states. For associated deaths, macrolide-resistant S. pneumoniae led in eight countries including China, Malaysia and Singapore, and aminopenicillin-resistant E. coli was the principal contributor in seven, including Indonesia, the Philippines, Australia and New Zealand. The authors flag one caveat: their classification of carbapenem-resistant S. pneumoniae reflects a harmonised resistance profile that may overestimate true carbapenem resistance in that species, since pneumococcal resistance is largely driven by alterations in penicillin-binding proteins rather than the carbapenemase mechanisms seen in Gram-negative bacteria.

Projections to 2050 point to a substantial escalation. Under the reference scenario, deaths attributable to AMR in the region are forecast to rise by 89 percent compared with 2022, and associated deaths by 60 percent. The trends pull in opposite directions by age: attributable deaths in children under five are expected to fall by 47.2 percent from 2021 to 2050, while attributable deaths among people aged 70 and older are projected to increase by 194 percent. Cumulatively between 2025 and 2050, the models suggest 39.1 million deaths associated with AMR could occur in the region, of which 8.51 million would be directly attributable. China alone is projected to exceed 4.8 million cumulative attributable deaths, with Indonesia surpassing 1.3 million, Viet Nam exceeding 600,000, and Japan and the Philippines each approaching half a million. The all-age attributable DALY rate is forecast to climb from 476 to 784 per 100,000 population, driven largely by resistant infections among older age groups.

The study also explored links between AMR burden and broader development indicators. Age-standardised AMR mortality showed a strong inverse correlation with the Socio-demographic Index, a composite of income per capita, educational attainment and fertility rate, with a correlation coefficient of minus 0.84. Countries with fully implemented and financed national action plans on AMR, including Australia, Japan, New Zealand, Singapore and South Korea, tended to have lower mortality rates, although the authors stress this comparison is exploratory and no causal conclusions can be drawn. They note that reported plan status alone does not explain the observed burden, which is also shaped by surveillance capacity, health-system resources, antibiotic access and usage, infection prevention, and diagnostic and reporting capacity. Environmental factors may compound the picture: cited studies from China link rising ambient temperatures and lower socioeconomic status to increased carbapenem resistance, and a hazard assessment identified Western Pacific countries as potential hotspots for resistance emergence from antibiotic residues in wastewater, with fluoroquinolones and macrolides flagged as priority targets.

The authors acknowledge important limitations. Data linking laboratory findings to mortality and disability outcomes remain scarce, and many countries in the region lack sufficient data on pathogen distribution and resistance prevalence for key combinations. Countries with lower Socio-demographic Index values often have weaker surveillance systems and laboratory support, which may lead to underestimation of the true burden, meaning estimates for data-sparse settings should be interpreted with caution. Early estimates before 2000 relied heavily on modelled relationships, the COVID-19 pandemic disrupted microbiological testing, and the forecasts do not explicitly incorporate future changes in vaccine uptake, antimicrobial consumption, infection prevention or climate impacts, except insofar as these are reflected in broader reference projections. The projections are intended to indicate the likely direction and scale of future burden rather than precise country-level counts. Even so, the researchers argue the estimates provide a quantitative foundation for policy prioritisation, resource allocation and the implementation of national AMR action plans, underscoring the need for One Health approaches that span human, animal and environmental sectors, strengthened diagnostics and outcome-based surveillance across a region where no country can tackle resistance in isolation.

Subject of Research: The burden of bacterial antimicrobial resistance in the WHO Western Pacific Region from 1990 to 2021 with forecasts to 2050

Article Title: The burden of bacterial antimicrobial resistance in the WHO Western Pacific Region 1990–2021: a cross-country systematic analysis with forecasts to 2050

Article References: Mestrovic, T., Aguilar, G. R., Weaver, N. D., Araki, D. T., Hayoon, A. G., Gray, A. P., Han, C., Hsu, R. L., Ikuta, K. S., Swetschinski, L. R., Wool, E. E., Abdulraheem, R. A., Aboagye, R. G., Addo, I. Y., Adegoke, N. A., Adhikary, R. K., Sakilah Adnani, Q. E., Afrifa-Yamoah, E., Ahmad, D., … Naghavi, M. (2026). The burden of bacterial antimicrobial resistance in the WHO Western Pacific Region 1990–2021: a cross-country systematic analysis with forecasts to 2050. The Lancet Regional Health – Western Pacific, 75, Article 101997. https://doi.org/10.1016/j.lanwpc.2026.101997

Image Credits: AI Generated

DOI: 10.1016/j.lanwpc.2026.101997

Keywords: antimicrobial resistance, WHO Western Pacific Region, global burden of disease, drug-resistant infections, Staphylococcus aureus, bloodstream infections, AMR forecasting, national action plans, Socio-demographic Index, Pacific Island countries, One Health, public health surveillance