Residual risk of HIV transmission through blood transfusion in five blood banks in Cameroon

Background: Cameroon remains a country with high HIV prevalence among blood donors so there is a need for surveillance of HIV transmission through blood transfusion in order to evaluate blood safety and justify the change of screening strategy. The last evaluation of the HIV screening strategy in Cameroon in 2011 revealed that 55 HIV transmissions per 10,000 of blood donations could have prevented using a four generation assay than using a combination of third generation Rapid diagnostic test and Enzyme immuno-Assay. Aims and objectives: This study aimed to estimated and compare the HIV transmission risk among blood banks using different testing strategies. Study design and setting: A one year multi-center data records review study was conducted in five Blood Banks located in five regions of Cameroon in 2018. These Blood Banks were made of Yaounde Central Hospital (YCH), Douala Laquintinie Hospital (DLH), Bertoua Regional Hospital (BRH), Ebolowa Regional Hospital (ERH) and Maroua Regional Hospital (MRH). Material and methods: Records were reviewed using data from the 1 January to the 31 December 2017. Five blood banks out of 18 were selected based on the use of national standardized registries and properly completed data. The World Health Organisation incidence/window period model was used to estimate the residual risk. Statistics: The incidence (percentage and 95% confidence interval) of HIV was calculated per 100,000 blood donations in 2017. The chi-square test was used to measure the association between groups and P-values <0.05 were considered significant. The study was approved by the National Institutional Ethics Committee. Results: Overall, 22,980 blood donor candidates were received and 20,430 (88.90%) [95% CI, 88.49-89.30] were tested for HIV. Among the 20,430 tested for HIV, 1827 (8.94%) [95% CI, 8.55-9.34] donated at least twice. HIV prevalence was estimated at 471/20,430 (2.31%) [95% CI, 2.11-2.52] among blood donors with an inconclusive rate of 701/20,430 (3.43%) [95% CI, 3.19-3.69]. Comparing HIV prevalence per Region between blood donors and the general population, the prevalence was mostly lower among blood donors than in the general population except in YCH and MRH. The rate of reactivity of the first-line test differ with the one of the second-line test with a kappa agreement of 0.556 (0.5260.585: CI 95%) giving a moderate level of agreement between first and second-line test. Considering the HIV testing algorithm, incidence rates ranged from 411.52 to 1946.47 per 100,000 person-year corresponding to a residual risk to transmit HIV associated with the window period varied from 1 in 669.7 donations to 1 in 5543.54 donations. At the blood banks level, the incidence rates ranged from 382.41 to 2834.01 per 100,000 person-year and the residual risk to transmit HIV associated with the window period varied from 1 in 460 donations to 1 in 5965 donations. Conclusion: The residual risk of HIV transmission remains high in Cameroon and varies according to the screening strategies. Thus, there is a need to revise the HIV testing strategy and implement an existing plan to recruit and retain voluntary and regular blood donors.