The forgotten billion: bridging the global allergy care chasm through scalable, equity-driven strategies.

Background: Allergic diseases affect more than one billion people globally, yet care access is profoundly unequal. The "forgotten billion" refers to underserved populations-especially in LMICs and marginalized groups within high-income countries-who face disproportionate morbidity and preventable deaths due to gaps in diagnosis, essential medicines, immunotherapy and biologics, trained workforce, and policy prioritization. Objective: To synthesize recent (2014-2026) evidence on global burden and inequities in allergic disease care, analyze system-level gaps, review scalable innovations, present diverse case studies, and propose prioritized recommendations, monitoring frameworks, and a research and financing agenda. Methods: We conducted a structured narrative review of peer-reviewed literature and global guidance documents, focusing on burden metrics (prevalence, DALYs, mortality), access indicators, interventions (task-sharing, telemedicine, point-of-care tools, immunotherapy access, digital health, procurement/policy levers), and implementation science frameworks. Sources prioritized include WHO materials and guideline bodies (GINA, ARIA, EAACI), plus global reports and primary studies. Results: Asthma illustrates the equity chasm: in 2019 it caused approximately 21.6 million DALYs and approximately 461,000 deaths globally, with approximately 90% of burden borne in LMICs and most deaths occurring in LMICs. Systematic reviews show essential inhaled asthma medicines-especially inhaled corticosteroids (ICS) and ICS-containing combinations-are often unavailable or unaffordable in LMICs. Scalable strategies with documented impact include task-shifted care packages (Malawi), standardized primary care training (South Africa), community health worker home visiting (Boston), and public-sector access programs (Brazil), alongside national allergy strategies (Finland). Conclusions: Closing the allergy care chasm requires shifting from specialist-centric innovation to systems-first equity: universal access to essential medicines and equitable pathways to targeted therapies for severe disease, standardized primary care delivery with task-sharing, market-shaping and pricing policy reform, digitally enabled self-management designed to reduce (not widen) inequities, and integrated environmental action. Implementation must be measured with equity-sensitive frameworks and supported by durable financing aligned with UHC and NCD agendas.