Algorithm for recall of HIV reactive Indian blood donors by sequential immunoassays enables selective donor referral for counseling

Background: HIV/AIDS pandemic brought into focus the importance of safe blood donor pool.
Aims: To analyze true seroprevalence of HIV infection in our blood donors and devise an algorithm for donor recall avoiding unnecessary referrals to voluntary counseling and testing centre (VCTC).
Materials and Methods: 39,784 blood units were screened for anti-HIV 1/2 using ELISA immunoassay (IA-1). Samples which were repeat reactive on IA-1 were further tested using two different immunoassays (IA-2 and IA-3) and Western blot (WB). Based on results of these sequential IAs and WB, an algorithm for recall of true HIV seroreactive blood donors is suggested for countries like India where nucleic acid testing or p24 antigen assays are not mandatory and given the limited resources may not be feasible.
Results: The anti-HIV seroreactivity by repeat IA-1, IA-2, IA-3 and WB were 0.16%, 0.11%, 0.098% and 0.07% respectively. Of the 44 IA-1 reactive samples, 95.2% (20/21) of the seroreactive samples by both IA-2 and IA-3 were also WB positive and 100% (6/6) of the non-reactive samples by these IAs were WB negative. IA signal/cutoff ratio was significantly low in biological false reactive donors. WB indeterminate results were largely due to non-specific reactivity to gag protein (p55).
Conclusions: HIV seroreactivity by sequential immunoassays (IA-1, IA-2 and IA-3; comparable to WHO Strategy-III) prior to donor recall results in decreased referral to VCTC as compared to single IA (WHO Strategy-I) being followed currently in India. Moreover, this strategy will repose donor confidence in our blood transfusion services and strengthen voluntary blood donation program.