(P-TS-37) Comparison of Three Methods for the Estimation of the Residual Risk of HBV and HCV Infections Transmitted Through Blood Transfusion in an Upper-Middle-Income Country in Latin America

Background/Case Studies:

Background: In Colombia NAT testing is not currently mandatory. Conducting residual risk (RR) studies for transfusion-transmitted infections (TTIs) – HIV, HBV, and HCV – remains a priority in upper-middle-income Latin American countries for several interrelated reasons. The combination of still-significant viral loads, disparate infrastructure, and international targets makes it essential to conduct periodic residual risk studies. Furthermore, limited information is available on this topic.



Aims: Calculate the RR of HBV and HCV TTI in Colombia using two methods according to the most updated public information available and compared with previous studies.

Study

Design/Methods: Methods: Two methods were applied to estimate the RR of ITT for HBV and HCV. Method 1: Using an adjustment to WHO guidelines Annex 4(1) the RR was estimated based on data of incidence in the general population obtained from Coalition for Global Hepatitis Elimination(2). Method 2: Monitoring and tracking of NAT windows detected between 2018 and 2023 and reported by the National Institute of Health(3). The results obtained were compared with previous study from 2018(4) using the Decision Tree and Markov method (Method 3).

Results/Findings:

Results: With an incidence in the general population reported of 3.9 and 6.6 new infections per 100,000 for HBV and HCV respectively, the RR was estimated at 491 and 194 under the current screening strategies and 316 and 26 assuming universal NAT, for HBV and HCV respectively. During the 2018 and 2023 in 6 NAT windows were detected (3 for HBV, 3 for HCV) in 409,047 donations.

Table 1. RR Calculation for HBV and HCV, Colombia (in million donations)

		Method 1. Incidence in the general population	Method 2. NAT Windows tracking	Method 3. Decision Tree & Markov(4)
HBV	RR Serology	491	NA	194
	RR NAT	316	7	125
HCV	RR Serology	194	NA	710
	RR NAT	26	7	71

Conclusions:

Conclusion: The RR of ITT decreases when NAT tests are added to blood donation screening in all methods applied. These studies are essential for maintaining and improving the safety of the blood supply, adapting health strategies to specific contexts, and reducing the risk of ITT in the country. They are the basis for technical, financial, and regulatory decisions that maintain confidence in transfusion therapy and advance toward increasingly safer blood.