Rabies viral RNA and antibody response after post-exposure prophylaxis: Implications for blood donor deferral

Rabies post-exposure prophylaxis (PEP) using anti-rabies vaccine and immunoglobulin is widely recognized as highly effective. However, individuals who receive PEP are typically deferred from blood donation for a full year, largely due to theoretical concerns about transfusion safety. However, the evidence supporting such a prolonged deferral remains limited. This study aimed to assess rabies real-time RT-PCR status and serological responses among PEP recipients at various intervals following treatment and to consider whether these findings might justify a re-examination of the current one-year blood donor deferral policy after anti-rabies treatment. We conducted a single-center interventional study at an anti-rabies clinic in a tertiary hospital in North India. The study enrolled twenty immunologically naïve adults who had sustained category III animal bites, with no prior rabies exposure or treatment, and who adhered fully to the protocol. Participants received anti-rabies vaccines and equine rabies immunoglobulin as appropriate for their category. Follow-up samples were collected between as early as 48 days and 120 days after the bites. These samples were tested for rabies viral RNA using real-time RT-PCR (Geno-Sens Rabies Real-Time PCR Kit), and antibody titers were measured using ELISA (Rabies Platelia Kit II). Data analysis included descriptive statistics, percentile analysis, correlation analysis, and regression analysis, as appropriate. In this cohort, dogs were responsible for 90% of bites, with 85% of incidents being unprovoked and 65% involving lower limbs. All participants tested negative using RT-PCR. ELISA titers ranged from 0.881 to 4.449 IU/mL, and all participants exceeded the protective threshold of 0.5 IU/mL. The mean titer was 2.97 ± 1.04 IU/mL. The lack of detectable rabies viral RNA, together with sustained protective antibody titers, indicates an effective response to PEP in this group. These findings support a more evidence-based reconsideration of the current prolonged blood donor deferral following anti-rabies treatment. Rabies remains a major public health concern in India, where most human exposures occur after animal bites, especially dog bites. Post-exposure prophylaxis using anti-rabies vaccine and rabies immunoglobulin is highly effective when given correctly. However, people who receive anti-rabies treatment are often deferred from blood donation for one year, mainly because of theoretical concerns about transfusion safety. Evidence supporting such a long deferral period is limited. In this study, we followed 20 immunologically naïve adults with category III animal bites who received standard anti-rabies post-exposure prophylaxis. Blood samples were collected 48 to 120 days after exposure and tested for rabies viral RNA using real-time RT-PCR and for rabies antibody levels using ELISA. All participants were RT-PCR negative, indicating no detectable rabies viral RNA. All also had antibody levels above the accepted protective threshold. These findings suggest that individuals who complete appropriate anti-rabies post-exposure prophylaxis may not have detectable circulating viral RNA and maintain protective antibody responses during follow-up. Larger multicenter studies are needed, but these results support reconsideration of the current one-year blood donor deferral. Our findings suggest the potential for shortening the current one-year deferral for PEP recipients, supporting evidence-based transfusion policies after anti-rabies treatment.