They could have been infected by locals in regions they've been travelling to. Many possibilities. Why do we have to speculate? Let's just wait for more data.
The timeline of HIV pandemic has been established decades after pandemic started. This will take time.
I'd assume that virus originating anywhere in SEA region would be detected in China first. Just like many other viruses originating in America continent would be first detected in USA.
The timeline of HIV pandemic has been established decades after pandemic started. This will take time.
I'd assume that virus originating anywhere in SEA region would be detected in China first. Just like many other viruses originating in America continent would be first detected in USA.