Although positioned between five much larger neighbours with more serious epidemics, until recently Lao PDR remained less vulnerable to HIV/AIDS, largely thanks to the isolation of many communities.

The National Committee for the Control of AIDS Bureau estimates only 0.04% prevalence in the population at large, but there are fears that this low rate will not continue for long.

Every province in Lao PDR shares a border with Myanmar, China, Viet Nam, Cambodia and/or Thailand. Migrants from Lao PDR frequently cross into neighbouring countries or move to Lao PDR's major cities to seek work. Current estimates of HIV/AIDS prevalence may well be too low, as the national surveillance system is not yet picking up returnees among the very large numbers of young Lao people work in Thailand, including, increasingly, young women and men in sex work.

Lao PDR's geographic position, and some major infrastructure and industrial development projects, are bringing foreign truck drivers, engineers, construction teams and traders into the economic centres. Karaoke bars, brothels and other direct or indirect commercial sex venues have grown up to serve this new market, despite official prevention efforts. This population mobility is allowing HIV to penetrate further and further into rural Lao PDR.

Other factors making Lao PDR vulnerable to HIV/AIDS include frequent re-use of unsterilized injecting equipment, both in medical settings and among injecting drug users – new syringes retail at a quarter of the average daily wage (estimated by the Asian Harm Reduction Network in 1998). Use of alcohol and, to a lesser extent, recreational drugs among the young is growing, which could weaken prevention efforts.