Eurosurveillance - Volume 31, Issue 8, 26 February 2026

Transmitted integrase inhibitor resistance in newly diagnosed HIV remains rare. We report two cases with baseline resistance to all currently available integrase inhibitors in the Netherlands in 2025. Clinical history and laboratory findings indicate possible transmitted resistance. The cases are not phylogenetically linked, representing two independent introductions of integrase inhibitor resistant HIV into the Dutch population. These observations highlight the need for strengthened surveillance and prevention efforts in Europe and globally.

In February 2022, we observed an increase in the number of paediatric patients with haemolytic uraemic syndrome (HUS) associated with Shiga toxin-producing Escherichia coli (STEC) in France. We interviewed cases or caretakers about food exposures, identified purchases on supermarket loyalty cards, conducted a case–control study, tested food samples and characterised isolates. We identified 59 cases of STEC O26:H11 or O103:H2 infections nationwide from 18 January to 5 April 2022. Fifty cases presented with HUS and two died. Data from supermarket loyalty cards identified frequent purchase of Brand A Type B frozen pizzas. A case–control study confirmed a strong association between the consumption of Brand A pizzas and illness (OR = 116.0; 95% confidence interval (CI): 26.8–501.9). Manufacturing of Brand A Type B pizzas did not include pre-baking of the dough. Isolates from pizza dough and flour samples were indistinguishable from the clinical outbreak strains. On 18 March, the manufacturer recalled the Type B pizzas. While flour is a known STEC vehicle, this outbreak is highly unusual, as cooking of frozen pizzas should eliminate STEC. Further research aiming to understand the origins and persistence of contamination should contribute to improving food safety practices.

Annual reformulation and approval of seasonal influenza vaccines necessitate yearly evaluation of their effectiveness. Regulatory agencies, including the European Medicines Agency (EMA), rely on timely, real-world evidence to inform product-specific benefit-risk assessments. We explored the feasibility of conducting annual, brand-specific influenza vaccine effectiveness studies in Denmark, Finland and Sweden, starting with the 2024/25 season. These countries maintain population-wide vaccination, clinical and laboratory registers, linkable via personal identification numbers and updated in near real-time. We discuss suitable study designs and document that cohort studies using a target trial emulation (TTE) framework are feasible in all three countries; register-based test-negative case-control design (TND) studies are currently only feasible in Denmark. Supplementary methods, including regression discontinuity and negative control outcome analyses, can address residual bias. This Nordic collaboration has proven capacity for large-scale register-based studies and its infrastructure is able to address EMA’s requirements for timely, robust post-authorisation evidence to guide public health and regulatory decisions.