The declining trend in HIV prevalence from population-based surveys in Cameroon between 2004 and 2018: myth or reality in the universal test and treat era?

BACKGROUND

HIV remains an epidemic of major public health importance in Cameroon but a decline in HIV prevalence has been observed according to population-based surveys conducted in 2004, 2011 and 2018. We sought to review current evidence for declining HIV prevalence despite increasing survival owing to 'universal test and treat' and to explore the reason for the decrease, particularly the role of behavioural change.

METHODS

We conducted a secondary analysis using HIV prevalence, behavioural and social determinants data of the Demographic and Health Survey Program databases. Trend lines were fitted to data that were available for a minimum of three points in time during the 1991-2018 period. Regression coefficients associated p-values and 95% confidence intervals were obtained using Microsoft Excel software.

RESULTS

Overall adult HIV prevalence decreased significantly from 5.4% (95%CI: 4.8-6.0) in 2004 to 4.3% (95%CI: 3.8-4.8) in 2011 and further down to 2.7% (95%CI: 2.3-3.1) in 2018 at a rate of about 1.4% every septennium (β = -1.4, R² = 0.98, p = 0.03). Yet, the number of persons surviving with HIV increased from about 0.05 million in 1991 to 0.5 million in 2018 corresponding to an increase in access to antiretroviral therapy from less than 10% to universal coverage of 80% respectively. Concurrent reductions in risky sexual behaviours were observed: a delayed sexual debut by one year, decreased sexual violence by 7%, decreased polygamous unions by 16%, decreased multiple sexual partners by 15.3% and increased condom use by 26.3%.

CONCLUSION

The observed decline in HIV prevalence is statistically valid and reflects the observed decline in risky sexual behaviour that need to be sustained by the National HIV programme. Though universal access to ART has increased the number of persons surviving with HIV, this has not led to an increased prevalence of HIV in a setting with a rising population.

Evaluation of multi-assay algorithms for cross-sectional HIV incidence estimation in settings with universal antiretroviral treatment

BACKGROUND

Multi-assay algorithms (MAAs) are used to estimate population-level HIV incidence and identify individuals with recent infection. Many MAAs use low viral load (VL) as a biomarker for long-term infection. This could impact incidence estimates in settings with high rates of early HIV treatment initiation. We evaluated the performance of two MAAs that do not include VL.

METHODS

Samples were collected from 219 seroconverters (infected < 1 year) and 4376 non-seroconverters (infected > 1 year) in the HPTN 071 (PopART) trial; 28.8% of seroconverter samples and 73.2% of non-seroconverter samples had VLs ≤ 400 copies/mL. Samples were tested with the Limiting Antigen Avidity assay (LAg) and JHU BioRad-Avidity assays. Antibody reactivity to two HIV peptides was measured using the MSD U-PLEX assay. Two MAAs were evaluated that do not include VL: a MAA that includes the LAg-Avidity assay and BioRad-Avidity assay (LAg + BR) and a MAA that includes the LAg-Avidity assay and two peptide biomarkers (LAg + PepPair). Performance of these MAAs was compared to a widely used MAA that includes LAg and VL (LAg + VL).

RESULTS

The incidence estimate for LAg + VL (1.29%, 95% CI: 0.97-1.62) was close to the observed longitudinal incidence (1.34% 95% CI: 1.17-1.53). The incidence estimates for the other two MAAs were higher (LAg + BR: 2.56%, 95% CI 2.01-3.11; LAg + PepPair: 2.84%, 95% CI: 1.36-4.32). LAg + BR and LAg + PepPair also misclassified more individuals infected > 2 years as recently infected than LAg + VL (1.2% [42/3483 and 1.5% [51/3483], respectively, vs. 0.2% [6/3483]). LAg + BR classified more seroconverters as recently infected than LAg + VL or LAg + PepPair (80 vs. 58 and 50, respectively) and identified ~ 25% of virally suppressed seroconverters as recently infected.

CONCLUSIONS

The LAg + VL MAA produced a cross-sectional incidence estimate that was closer to the longitudinal estimate than two MAAs that did not include VL. The LAg + BR MAA classified the greatest number of individual seroconverters as recently infected but had a higher false recent rate.