More than half of all new HIV diagnoses among migrants in Switzerland occur years after they have relocated, according to findings presented at the 2025 European AIDS Clinical Society (EACS) Congress.
The study, which analyzed data from the Swiss HIV Cohort Study (SHCS) over a 15-year period, highlights shifting infection trends and the urgent need for more targeted HIV prevention and early testing strategies for migrant populations.
The SHCS tracked 3,490 participants enrolled between 2010 and 2024, excluding those with perinatal HIV infections. Of these, 1,777 were Swiss nationals and 1,713 were migrants.
Over time, the proportion of migrants joining the cohort increased steadily, with a median of 52% and an odds ratio of 1.07 per year (p<0.001). This reflects not only changing population dynamics in Switzerland but also the growing health importance of migrant communities.
Delayed detection among migrant groups
Among migrants, 62.1% were diagnosed with HIV after migration, while 37.9% received their diagnosis before arriving in Switzerland.
- The most common transmission route among post-migration cases was men who have sex with men (43.1%), followed by female heterosexuals (27.2%) and male heterosexuals (18.9%).
- Migrants diagnosed after migration had significantly lower CD4 counts compared to Swiss nationals, suggesting late detection. The time from immigration to diagnosis also varied by transmission route, six years for male heterosexuals, five years for MSM, and two years for female heterosexuals.
Researchers say distinguishing between infections acquired in Switzerland and delayed diagnoses of pre-existing infections is essential for improving testing and prevention strategies among migrant populations.
Beyond individual health implications, delayed diagnosis carries broader public health consequences. People unaware of their HIV status are less likely to access treatment early, increasing the risk of onward transmission. According to experts, the findings reinforce the need for inclusive, culturally sensitive public health strategies that bridge healthcare gaps among migrants.
What you should know
Experts note that these findings mirror trends seen across Europe, where migrants from sub-Saharan Africa and other non-EU regions are disproportionately affected by late HIV diagnoses. Barriers such as language differences, stigma, and limited healthcare access often delay testing and treatment.
Africans represent a significant portion of the migrant HIV population in Europe.
- A report by the UK Health Security Agency revealed that a majority of migrants, including those born in Africa, acquired HIV post-migration, with about 65% of MSM cases diagnosed after relocation.
- Similarly, a multicounty study in AIDS Journal found that 63% of migrants across nine European nations acquired HIV after migration, including 45% of sub-Saharan Africans (see study).
- Further data from Eurosurveillance (2024) showed that nearly half of new HIV diagnoses in the EU/EEA between 2014 and 2023 were among migrants, and more than half (52%) of those cases were late diagnoses (read report). Earlier findings from the ECDC also indicated that migrants from sub-Saharan Africa had the highest odds of late HIV presentation.
