HIV Incidence, Recent HIV Infection, and Associated Factors, Kenya, 2007-2018

Abstract

Nationally representative surveys provide an opportunity to assess trends in recent human immunodeficiency virus (HIV) infection based on assays for recent HIV infection. We assessed HIV incidence in Kenya in 2018 and trends in recent HIV infection among adolescents and adults in Kenya using nationally representative household surveys conducted in 2007, 2012, and 2018. To assess trends, we defined a recent HIV infection testing algorithm (RITA) that classified as recently infected (<12 months) those HIV-positive participants that were recent on the HIV-1 limiting antigen (LAg)-avidity assay without evidence of antiretroviral use. We assessed factors associated with recent and long-term (≥12 months) HIV infection versus no infection using a multinomial logit model while accounting for complex survey design. Of 1,523 HIV-positive participants in 2018, 11 were classified as recent. Annual HIV incidence was 0.14% in 2018 [95% confidence interval (CI) 0.057-0.23], representing 35,900 (95% CI 16,300-55,600) new infections per year in Kenya among persons aged 15-64 years. The percentage of HIV infections that were determined to be recent was similar in 2007 and 2012 but fell significantly from 2012 to 2018 [adjusted odds ratio (aOR) = 0.31, p < .001]. Compared to no HIV infection, being aged 25-34 versus 35-64 years (aOR = 4.2, 95% CI 1.4-13), having more lifetime sex partners (aOR = 5.2, 95% CI 1.6-17 for 2-3 partners and aOR = 8.6, 95% CI 2.8-26 for ≥4 partners vs. 0-1 partners), and never having tested for HIV (aOR = 4.1, 95% CI 1.5-11) were independently associated with recent HIV infection. Although HIV remains a public health priority in Kenya, HIV incidence estimates and trends in recent HIV infection support a significant decrease in new HIV infections from 2012 to 2018, a period of rapid expansion in HIV diagnosis, prevention, and treatment.

Keywords: HIV incidence estimation; HIV surveillance; Kenya; antiretroviral treatment; population surveys; tests for recent infection.

FIG. 1.

Recent HIV infection testing algorithms. ART, antiretroviral treatment; ARV, antiretroviral; c/mL, copies per mL; EIA, enzyme-linked immunosorbent assay; HIV, human immunodeficiency virus; LAg, limiting antigen; RITA, recent HIV infection testing algorithm; VL, viral load.

FIG. 2.

Recent HIV infection testing status for specimens according to harmonized and full RITA, Kenya, 2007–2018. All numbers are unweighted and exclude North Eastern region. *Includes four specimens with missing ARV test result (self-reported not on ART). ^†Includes 22 specimens with missing ARV test result (self-reported not on ART). §Includes one specimen with missing VL result. ^αIncludes five specimens with missing ARV test (self-reported on ART). ^βIncludes six specimens with missing ARV test (self-reported not on ART). ^γIncludes two specimens with positive ARV test result but missing self-reported ART status. Harmonized RITA is based on LAg and ART (self-report and biomarker), full RITA is based on LAg, ART (self-report and biomarker) and VL ≥1,000 c/mL. ART, antiretroviral treatment; RITA, recent HIV infection testing algorithm.