Opposite Directions: A Decade of Contrasting HIV and HCV Dynamics Among Injecting Drug Users in Mozambique

This study reveals a decade-long divergence in Mozambique among people who inject drugs, characterized by a significant decline in HIV prevalence alongside a sharp, geographically and demographically varied increase in hepatitis C virus prevalence, underscoring the urgent need for differentiated harm-reduction strategies and expanded HCV services.

The Gist

Imagine Mozambique as a large house with two main rooms: Maputo (the capital) and Nampula (a major city in the north). Inside this house lives a specific group of people who inject drugs. For the last decade, health workers have been checking the "health status" of these two rooms to see how two invisible invaders—HIV and Hepatitis C (HCV)—are behaving.

This study is like taking a snapshot of the house in 2014 and comparing it to a new snapshot taken in 2023. Here is what they found, explained simply:

1. The Tale of Two Invaders

Think of HIV and Hepatitis C as two different types of burglars trying to break into the house.

• The HIV Burglar (The One Getting Thrown Out):
  In 2014, HIV was everywhere in the house, especially in Maputo. But by 2023, the homeowners (health services) had installed better locks and alarms. The HIV burglar was successfully kicked out of most rooms.

  • The Result: HIV rates dropped dramatically. In Maputo, it fell from over half the people being infected to less than a third. Even among the most vulnerable groups (like daily injectors), the numbers went down significantly. It's like the HIV burglar tried to break in, but the new security system worked.

• The Hepatitis C Burglar (The One Sneaking In):
  This burglar is sneakier and harder to stop. While the HIV rates went down, Hepatitis C did something strange.

  • In Maputo: The Hepatitis C burglar also got kicked out (rates dropped).
  • In Nampula: The burglar didn't just stay; it exploded. In 2014, only a few people in Nampula had it. By 2023, nearly half of the people in that room were infected. It's like the security system in the north room was left open, and the burglar moved in and took over.

2. The "New Kids" Problem

There is a worrying trend regarding age.

• Older Injectors: The older people (25+) who had been injecting drugs for a long time are actually getting safer. They are using clean needles more often, so they are less likely to catch these viruses.
• Younger Injectors: The "new kids" (ages 16–24) are entering the scene with a massive problem. In Nampula, the rate of Hepatitis C among young people jumped five times higher in just a few years. It's like a new generation is walking into a room full of dirty needles without knowing the danger, getting infected immediately.

3. Why the Difference? (The "Clean Needle" Analogy)

Why did HIV go down while Hepatitis C went up in some places?

• HIV is like a slow leak: It takes a lot of exposure to get infected. Because health programs gave out more clean needles and HIV tests, they managed to plug the leak.
• Hepatitis C is like a fire: It spreads much faster and more easily through dirty needles. Even if you have some clean needles, if you don't have enough to cover everyone, the fire (Hepatitis C) can still spread rapidly. The study suggests that while Mozambique did a great job stopping the HIV leak, they didn't have enough "fire extinguishers" (clean needles and treatment) to stop the Hepatitis C fire in Nampula.

4. The Gender Gap

The study also found that women who inject drugs are still in much more danger than men.

• Imagine a woman trying to navigate a dark alley. She faces not just the risk of the viruses, but also stigma, violence, and fewer resources. Even though the overall numbers are dropping, women are still catching the virus at much higher rates than men. They need a special "flashlight" and extra protection that the current system isn't fully providing yet.

5. The Bottom Line: A Mixed Report Card

If Mozambique's health system were a student taking a test:

• HIV Grade: A-** (Great job! You stopped the spread in most places, but you still need to help the women and the young people).
• Hepatitis C Grade: D+ (In the north, you failed to stop the spread. In the south, you did well, but the problem is growing fast in the wrong places).

What Needs to Happen Next?

The authors say we can't use the same "one-size-fits-all" strategy anymore.

• In Maputo: Keep doing what works (more testing, more clean needles).
• In Nampula: You need an emergency response. You need to flood the area with clean needles, test everyone immediately, and treat Hepatitis C aggressively before it spreads further.
• For Everyone: We need to specifically target the young people entering the scene and ensure women have safe, private access to help.

In short: Mozambique made huge progress against HIV, but Hepatitis C is a new, growing threat in specific areas that requires immediate, targeted action to prevent a new epidemic.

Technical Summary

1. Problem Statement

People who inject drugs (PWID) in sub-Saharan Africa face a high burden of HIV and Hepatitis C virus (HCV) due to unsafe injection practices and limited access to harm-reduction services. Despite global commitments to end AIDS and eliminate viral hepatitis by 2030, PWID remain a largely invisible population in national surveillance systems.

• The Gap: Mozambique, a high HIV-burden country, lacks longitudinal data on PWID. While the first Bio-Behavioral Survey (BBS) was conducted in 2013–2014, there was no comparable data for a decade.
• The Challenge: Understanding how HIV and HCV epidemics are evolving among PWID is critical for designing targeted interventions, particularly given the potential for divergent transmission dynamics between the two viruses.

2. Methodology

This study is a secondary analysis of two cross-sectional Bio-Behavioral Surveys (BBS) conducted among PWID in Mozambique.

• Study Design & Period:
  • Round 1: 2013–2014 (Maputo and Nampula).
  • Round 2: 2023–2024 (Expanded to Maputo, Nampula, Beira, Tete, and Quelimane).
  • Analysis Focus: To ensure comparability, the analysis was restricted to participants aged 18 years and older.
• Sample Size:
  • 2014: 492 PWID with valid HIV tests.
  • 2023: 2,624 PWID with valid HIV tests.
• Sampling Method: Respondent-Driven Sampling (RDS) was used for recruitment.
• Data Collection:
  • Standardized questionnaires covering socio-demographics, drug use history, injection practices (sharing, frequency), sexual behaviors, and service access.
  • Biological Testing:
    • HIV: Sequential algorithm (Alere Determine® screening + Uni-Gold™ confirmation).
    • HCV: SD Bioline HCV rapid antibody test (all reactive results treated as positive for prevalence estimation).
• Statistical Analysis:
  • Descriptive: Unweighted prevalence estimates were calculated (RDS weighting was omitted as data was aggregated across multiple cities, and RDS estimators are valid only within single networks).
  • Inferential: Chi-square tests for proportion equality; Multivariable logistic regression to identify independent risk factors.
  • Interaction Analysis: Pairwise interactions between survey year and explanatory variables were included to assess temporal changes in risk factors.
  • Software: R statistical software (v4.4.1).

3. Key Contributions

• First Longitudinal Assessment: This is the first study to provide a decade-long (2014–2023) comparison of HIV and HCV prevalence among PWID in Mozambique.
• Divergent Epidemic Trends: It uniquely documents the "opposite directions" of the two epidemics: a significant decline in HIV prevalence contrasted with a sharp, geographically specific rise in HCV.
• Subgroup Identification: The study identifies critical shifts in risk profiles, specifically the emergence of high HCV risk among younger PWID (16–24 years) and the geographic polarization of HCV transmission.

4. Key Results

A. HIV Trends (Significant Decline)

• Overall: HIV prevalence dropped significantly across almost all demographic and behavioral groups.
  • Age (≥25): Decreased from 55.7% (2014) to 26.3% (2023).
  • Gender (Men): Decreased from 45.7% to 16.7%.
  • Daily Injectors: Decreased from 58.0% to 21.3%.
  • Syringe Sharing: Decreased from 75.0% to 21.8%.
• Geography:
  • Maputo: Significant decline (56.6% → 28.0%).
  • Nampula: Non-significant decline (20.0% → 14.2%).
• Risk Factors (Multivariable):
  • Older age (≥25) and female sex were strong predictors of HIV in 2014, though the age effect weakened in 2023.
  • Not sharing needles and lower injection frequency were protective.
  • In 2023, lack of recent HIV testing was associated with higher odds of infection.

B. HCV Trends (Divergent & Rising)

• Overall: HCV trends were heterogeneous, showing a stark geographic divide.
  • Maputo: Significant decline (49.3% → 18.7%).
  • Nampula: Dramatic increase (11.7% → 48.1%).
• Age Dynamics:
  • Younger PWID (16–24): Prevalence surged from 7.3% to 38.7% (a fivefold increase).
  • Older PWID (≥25): Prevalence declined (45.3% → 28.8%).
• Risk Factors (Multivariable):
  • Location: Residing in Nampula was protective in the pooled model (AOR 0.2) but showed a massive interaction effect in 2023 (AOR 14.6), indicating a localized outbreak.
  • Behavior: Not sharing needles and lower injection frequency remained protective.
  • Sexual Behavior: Having two sexual partners was associated with higher HCV odds.

5. Significance and Implications

• Programmatic Success vs. Failure: The decline in HIV suggests that existing harm-reduction strategies (e.g., needle exchange, ART linkage, testing) have been effective in Mozambique. However, the rising HCV rates indicate these services are insufficient to interrupt HCV transmission, which requires higher coverage of sterile equipment due to its higher transmission efficiency via blood.
• Emerging Hotspots: Nampula has emerged as a critical HCV transmission hotspot, likely driven by expanding injecting networks and insufficient harm-reduction coverage.
• Generational Shift: The sharp rise in HCV among youth (16–24) signals a new cohort of injectors entering high-risk networks, necessitating urgent, age-targeted prevention.
• Policy Recommendations:
  1. Differentiated Strategies: Move away from one-size-fits-all approaches. Maputo requires consolidation of gains, while Nampula needs emergency HCV containment.
  2. HCV Scale-up: Immediate expansion of HCV testing, treatment (DAAs), and prevention services, particularly in Nampula.
  3. Gender Responsiveness: Continued focus on female PWID, who remain disproportionately affected by HIV.
  4. Youth Engagement: Tailored interventions for the 16–24 age group to prevent new HCV infections.

Conclusion: The study highlights a "success story" for HIV control but a "warning signal" for HCV. Without differentiated, intensified interventions, the gains in HIV control could be undermined by a growing HCV epidemic among vulnerable subgroups in Mozambique.