HIV incidence, migration and diagnosis dynamics, France, 2012-2023: a surveillance and modeling data analysis.

Background: In France, new HIV diagnoses have declined since 2012 among native-born men who have sex with men (MSM) but not among MSM or heterosexuals born abroad. We aimed to disentangle and describe trends in HIV incidence in France, migration of undiagnosed people living with HIV (PLHIV), and diagnosis delays among people born abroad.

Setting: France.

Methods: We applied a mathematical model that estimates individual-level diagnosis delay distributions and identifies likely pre-migration infections to surveillance data of new HIV diagnoses from France. We then applied a second model to estimate HIV incidence in France and the number of arriving migrants with pre-migration infections each year from 2012-2023. Denominators were estimated from official population statistics.

Results: The number of undiagnosed PLHIV arriving in France fell sharply during the COVID-19 pandemic before resuming previous trends; HIV incidence showed no such effect. Excluding this period, overall HIV incidence and migrations of undiagnosed PLHIV have been stable among people from sub-Saharan Africa (SSA) despite increasing immigration. However, they have increased among MSM born in SSA and other foreign countries. People with pre-migration infections are diagnosed at a later clinical stage of infection than people born in France, but generally within one year of arrival; people with post-migration infections have diagnosis delays similar to those born in France. Only 15% of undiagnosed PLHIV were infected pre-migration.

Conclusion: Progress in HIV prevention among people born abroad has been mixed. Preventing and diagnosing post-migration infections are key to preventing onward transmission.