There is a potentially high risk of HIV spreading from people living with HIV/AIDS. We conducted a cross-sectional study to examine HIV risk behaviours and their determinants among people living with HIV/AIDS. Eighty-two percent had been sexually active. Sex with multiple partners was reported by 20% and consistent condom use by about one third. More than half of the participants (52%) reported having injected drugs during the previous month, and 35% of those had shared needles and syringes. Voluntary HIV testing and having received condoms or injection equipment from the local HIV prevention program, were found to be significantly associated with fewer HIV risk behaviours. Having learned recently about personal HIV status, multiple sex partners, low educational attainment and young age were found to be associated with higher HIV risk behaviours. Giving high priority to targeted preventive and support programmes is likely to be a highly cost-effective strategy.

To investigate the nature of recent HIV outbreaks among injecting drug users (IDUs) near the Vietnam-China border, we genetically analyzed 24 HIV-positive blood specimens from 2 northern provinces of Vietnam (Lang Son and quang Ninh) adjacent to the China border, where HIV outbreaks among IDUs were first detected in late 1996. Genetic subtyping based on gag (p17) and env (C2/V3) sequences revealed that CRF01_AE is a principal strain circulating throughout Vietnam, including the provinces near the China border. The majority of CRF01_AE sequences among IDUs in Quang Ninh and Lang Son showed significant clustering with those found in nearby Pingxiang City of China's Guangxi Province, sharing a unique valine substitution 12 amino acids downstream of the V3 loop. This particular subtype E variant, uniquely found among IDUs in northern Vietnam and southeastern China, is designated E(v). The genetic diversity of CRF01_AE distributed in Quang Ninh (1.5 +/- 0.6%) and Pingxiang City (1.9 +/- 1.2%) was remarkably low, indicating the emerging nature of HIV spread in these areas. It is also noted that the genetic diversity of CRF01_AE among IDUs was consistently lower than that in persons infected sexually, suggesting that fewer closely related CRF01_AE variants were introduced into IDUs and, conversely, that multiple strains of CRF01_AE had been introduced via the sexual route. The data in the present study provide additional evidence that HIV outbreaks among IDUs in northern Vietnam were caused by the recent introduction of a highly homogeneous CRF01_AE variant (E(v)) closely related to that prevailing in nearby southern China.

The finding of marked geographical variation in HIV prevalence underscores the value of understanding local contexts in the prevention of HIV infection. Although lacking support from data from all provinces, there would appear to be a potential for sex work to drive a self-sustaining heterosexual epidemic. That the close links to serious injecting drug use epidemics can have an accelerating effect in increasing the spread of HIV merits further study.

Young SSWs who inject drugs are at the greatest risk of contracting HIV and acting as a bridge for HIV to the sexually active population.

We present a sample pooling approach and the results of its application for mass screening of SARS-CoV-2 in >96,000 asymptomatic individuals. Our approach did not compromise the sensitivity of PCR, while increasing the throughput and reducing 77% of the costs. 22/32 asymptomatic cases would have been missed without mass screening.