  Background: Men and women with a migration background comprise an increasing
proportion of incident HIV cases across Western Europe. Several studies
indicate a substantial proportion acquire HIV post-migration.
  Methods: We used partial HIV consensus sequences with linked demographic and
clinical data from the opt-out ATHENA cohort of people with HIV in the
Netherlands to quantify population-level sources of transmission to Dutch-born
and foreign-born Amsterdam men who have sex with men (MSM) between 2010-2021.
We identified phylogenetically and epidemiologically possible transmission
pairs in local transmission chains and interpreted these in the context of
estimated infection dates, quantifying transmission dynamics between
sub-populations by world region of birth.
  Results: We estimate the majority of Amsterdam MSM who acquired their
infection locally had a Dutch-born Amsterdam MSM source (56% [53-58%]).
Dutch-born MSM were the predominant source population of infections among
almost all foreign-born Amsterdam MSM sub-populations. Stratifying by two-year
intervals indicated shifts in transmission dynamics, with a majority of
infections originating from foreign-born MSM since 2018, although uncertainty
ranges remained wide.
  Conclusions: In the context of declining HIV incidence among Amsterdam MSM,
our data suggest whilst native-born MSM have predominantly driven transmissions
in 2010-2021, the contribution from foreign-born MSM living in Amsterdam is
increasing.
