HIV Drug Resistance surveillance protocols
At the end of 2011, more than 8 million people were receiving antiretroviral therapy (ART) in low- and middle-income countries, a dramatic 26-fold increase from December 2003. Despite the obvious benefits that rapid scale-up has had on AIDS-related morbidity and mortality, potential for emergence of HIV drug resistance (HIVDR) to antiretrovirals (ARVs) has been a major ongoing concern of public health experts.
In 2004, WHO in collaboration with HIVResNet network developed a global strategy for surveillance and monitoring of HIVDR. The strategy aims to:
- Inform the selection of first- and second-line regimens for ART, as well as antiretroviral drugs for prevention of mother-to-child transmission (PMTCT), at population level
- Support national HIV programmes in minimizing the emergence and transmission of HIVDR.
To achieve the aims of the strategy, WHO HIVResNet has developed population-level surveillance protocols designed to be implemented in low- and middle-income countries.
1.HIVDR in recently infected populations (transmitted HIV drug resistance)
WHO recommends a minimum resource strategy to assess transmitted HIVDR in geographic areas of resource-limited countries where transmitted HIVDR is likely to be seen first. Surveys use small sample sizes (N≤47) and truncated sequential sampling to classify transmitted HIVDR as low (<5%), moderate (5-15%), or high (>15%). Whenever possible, surveys are integrated into national sero-surveillance to maximize feasibility. Survey results document transmission of drug resistant-HIV and support national choice of future first- and second-line antiretroviral therapy and current pre- and post-exposure prophylaxis.
2. HIVDR in populations failing first-line ART(acquired HIVDR)
Two alternative protocols have been developed, one using a prospective design and one using cross-sectional design. Due to issues surrounding feasibility of implementation WHO is shifting focus to the cross sectional method described below.
The cross sectional survey method provides a snapshot of rates of viral load suppression and HIVDR amongst people with viological failure at representatively chosen ART clinics in a country. Specifically, results from this protocol:
- Classify the proportion of adult or pediatric patients failing first-line ART (defined as viral load ≥1000 copies/ml) at sentinel ART clinics and
- Describe the pattern of HIVDR in patients with detectable viral load
The survey using the prospective method is designed to 1.) Describe HIVDR at baseline and 12 months after ART initiation, 2.) Evaluate the percentage of the cohort achieving "HIVDR prevention" (defined as viral load suppression after 12 months of ART), and 3.) Be implemented at 10-15 ART sites in each country and repeated following a 3-year cycle.
- Protocol for population-based monitoring of HIVDR emerging during treatment and related program factors at sentinel ART clinics: 2012 update
- Protocol for cross sectional surveillance of acquired HIVDR in populations failing first-line ART
3. HIVDR in infants less than 18 months of age
Surveillance to assess HIVDR prevalence among HIV-infected children < 18 months of age will be critical for improving health outcomes and minimizing subsequent accumulation of DRMs among HIV infected children. This generic protocol describes a survey method to assess HIVDR using remnant dried blood spot specimens from a representative sample of children <18 months being tested for early infant diagnosis in resource-limited countries.