Measles Resurgence in Bangladesh, 2026: A Situational Analysis for Urgent Public Health Response
\textbf{Background} Measles has resurged globally in the post-pandemic period as routine immunisation recovery remains below the two-dose threshold required to interrupt transmission. Bangladesh, previously nearing measles--rubella elimination, entered 2026 with widening coverage gaps, depleted vaccine stocks, and increasing numbers of missed children. We conducted a situation analysis to assess the scale, concentration, and programmatic implications of the outbreak. \textbf{Methods} We performed a rapid mixed-evidence review from 1--15 April 2026 using data from WHO, UNICEF, DGHS bulletins, PubMed/MEDLINE, ReliefWeb, SEARO updates, and Bangla-language media. Of 46 records screened, 19 were included. Analysis was based on aggregated, publicly available surveillance and programme data. \textbf{Findings} By 15 April 2026, Bangladesh reported 19{,}161 suspected cases, 2{,}973 confirmed cases, 166 suspected deaths, and 32 confirmed deaths across 58 districts since 15 March 2026. The outbreak was spatially concentrated: the top two divisions accounted for 56.5\% of cases (HHI = 0.217). Children under five comprised 81\% of cases, including 34\% infants under nine months. Vaccination status showed 72\% zero-dose and 16\% partially vaccinated cases. Coverage declined from 88.6\% to 86\% for MR1 and from 89\% to 80.7\% for MR2 (2019--2024), leaving about 20 million children vulnerable. \textbf{Interpretation} The resurgence reflects accumulated immunity gaps rather than vaccine failure, driven by subnational inequities and programme disruption. Urgent priorities include targeted vaccination campaigns, restoration of vitamin A supplementation, strengthening paediatric care capacity, and integrating real-time surveillance into outbreak response.