Implementation of a comprehensive harm reduction programme successfully contained the HIV epidemic among people who inject drugs in Taiwan, investigators report in PLOS Medicine. The availability of free antiretroviral therapy lowered community viral load – a measure of infectiousness. Engagement with methadone replacement programmes reduced the relative risk of infection with HIV by 80%. There were no new HIV infections among former prisoners who were frequent users of needle exchange programmes.
“Our data indicate that implementation of a comprehensive harm reduction program…was followed by a significant reduction in the HIV incidence rate among PWID [people who inject drugs] in Taiwan,” comment the authors. “Maintaining high coverage of harm reduction services was associated with a sustained low HIV incidence rate and a decreased HIV prevalence among PWID.”
Worldwide, people who inject drugs are one of the populations most affected by HIV. There are an estimated 60,000 people who inject drugs in Taiwan. HIV rates were low until 2003. However, an epidemic rapidly emerged in 2004. This prompted the Taiwanese government to implement a comprehensive harm reduction programme for people who inject drugs. This has been nationwide since 2006 and comprises methadone maintenance treatment (MMT) and needle and syringe programmes (NSP). Moreover, antiretroviral therapy has been available for free in Taiwan since 1997.
Investigators wished to assess the impact of these programmes on HIV trends among people who inject drugs.
They designed a study involving two study populations. The first consisted of 3851 people who inject drugs who were sent to prison between 2004 and 2010 and who tested HIV positive on entering prison. Blood samples from these individuals were tested using BED HIV-1 capture enzyme immunoassays to determine HIV incidence. The other population comprised 2473 HIV-negative individuals who had been in prison for drug use crimes and were released in July 2007 as part of an amnesty. Follow-up of these individuals allowed the investigators to estimate the impact of participation in harm reduction programmes on their HIV risk.
The majority (60%) of people found to have HIV on entering prison had recently acquired HIV. However, there was evidence that the proportion of recent infections declined after the implementation of harm reduction programmes. In 2004, some 90% of all people who inject drugs who were found to have HIV on entering prison had recently acquired the virus. This had fallen to 46% in 2007 and to 34% in 2009.
In 2004, estimated HIV incidence among prisoners with a history of drug use in Taiwan was 6.44%. Incidence peaked at 18% in 2005. The introduction of the large-scale harm reduction programme was accompanied by a sharp fall in incidence. In 2007, it had fallen to 2%. Incidence was just 0.27% in 2010.
Community viral load also declined among prisoners, from a mean of 93,000 copies/ml in 2006 to a mean of 11,710 copies/ml in 2010. The proportion of people with a viral load below 1000 copies/ml increased from 21% in 2006 to 40% in 2010.
Total HIV prevalence among people who inject drugs in Taiwan increased substantially between 2004 and 2006. The increase slowed between 2007 and 2009, and fell slightly in 2010.
Follow-up of individuals released in the 2007 amnesty similarly showed that the harm reduction programme was preventing new HIV infections.
The HIV incidence rate among former prisoners who received methadone maintenance therapy was 1.65 per 1000 person-years. This contrasted with an incidence of 10.33 per 1000 person-years among former prisoners who did not receive this therapy. After controlling for potential confounders, the investigators found that engaging with methadone maintenance programmes reduced the risk of infection with HIV by 80% (HR = 0.20; 95% CI, 0.06-0.67).
There was a zero HIV incidence rate among frequent users of needle and syringe exchanges. This compared to an incidence rate of 0.5% among people who inject drugs who did not use such services.
“The government-initiated extensive harm reduction strategies for HIV prevention in Taiwan have been associated with a substantial reduction in the spread of HIV among PWID and appear to have controlled a rapidly emerging epidemic,” conclude the authors. “Our findings suggest that countries with high prevalence and incidence of HIV among PWID should also offer comprehensive harm reduction services to their populations.”
Huang Y-F et al. Changes in HIV incidence among people who inject drugs in Taiwan following introduction of a harm reduction program: a study of two cohorts. PLOS Medicine 11(4): e.1001625, 2014.