ABSTRACT
The endgame for eliminating HIV will become increasingly difficult as transmission persists in
populations who are the most marginalized from society, the hardest to reach with prevention
programs, and the most challenging to include in epidemiological studies. Although San
Francisco appears on track to achieve zero new HIV infections within the next few years, the
trajectory among people who inject drugs (PWID) lags behind. The slower rate of decrease in
HIV among PWID may be due to lower levels of awareness and uptake of pre-exposure
prophylaxis (PrEP). Meanwhile, neighboring Alameda County (home to Oakland) has seen little
decrease in the HIV epidemic, and outbreaks occur among PWID who are Black/African
American or experiencing homelessness. In addition to HIV, PWID in the US are experiencing a
surge in deaths due opioid overdose. To end the HIV epidemic and mitigate other health
disparities for PWID, data collection systems need to be more rapid, representative, and
responsive to this population at high risk. We therefore propose to create a new epidemiological
data collection system for PWID in Alameda and San Francisco counties called Brief
Longitudinal Incident Sentinel Surveillance (BLISS). We will recruit 600 PWID (300 each in
county) using a novel venue-based / peer-referral hybrid method called Starfish Sampling to
accrue a cohort and follow them longitudinally. Following HIV testing and a baseline
questionnaire, participants will be enlisted to provide monthly brief responses to 11 sentinel
events of high significance to the HIV and substance use epidemics (e.g., PrEP uptake or
discontinuation, harm reduction program utilization, overdose experiences). Monthly data will be
collected through smart phone and online technologies with in-person options as back up.
Selected sentinel events will trigger “deeper dive” data collection through ecological momentary
assessments (EMAs). The sample size is geared to detect events occurring at low rates in the
community as early warning signals and to obtain sufficient longitudinal data to assess causal
factors for HIV risk and preventive behaviors, particularly barriers and facilitators to PrEP use
and adherence. BLISS data will help identify and avert outbreaks, micro-target interventions,
prioritize those at highest risk, fill unmet care and prevention needs, and end the HIV epidemic.
