Perrine Parize, Sothy Touch, Vaomalala Raharimanga, Nisa Ya, Katherine E. L. Worsley‐Tonks, Lauriane Kergoat, Pisey Thai, Soa Fy Andriamandimby, Saraden In, Anou Dreyfus, Malen Chan, Mino Harimbola Razafindramparany, Veasna Duong, Ravo Ramiandrasoa, Yiksing Peng, Tineke Cantaert, Philippe Dussart, Guilherme Dias de Melo, Sowath Ly, Rindra Vatosoa Randremanana, Arnaud Tarantola, Hervé Bourhy
BACKGROUND: The abridged Institut Pasteur du Cambodge (IPC) 3-session intradermal (ID) rabies post-exposure prophylaxis (PEP) regimen has been shown to be as safe and immunogenic as the 4-session regimen previously recommended by WHO. This regimen reduces time, cost, improves adherence and access to PEP for underserved people. Our study aimed to compare long-term and anamnestic immune response after a rabies vaccine booster dose in people previously vaccinated with a 3 or 4-session ID PEP. METHODS: In this prospective, multi-site, comparative immunogenicity study, we measured rabies virus neutralizing antibody in 181 persons that had previously received 3- or 4-session ID PEP, 2, 5, or 10 years earlier in Cambodia or Madagascar, at day 0 and at day 7 after a booster. In addition, RABV-specific T cell response was evaluated in a sub-group of 35 Cambodian participants. RESULTS: All participants had rabies virus neutralizing antibody titers considered adequate (≥ 0.5 IU/mL) on day 7 after the booster dose. The overall geometric mean titer (GMT) of rabies antibody on day 0 and day 7 did not differ significantly between the 2 groups. Furthermore, RABV-specific T cell response was similar regardless of the ID PEP regimen initially received in a sub-group of 35 participants. CONCLUSIONS: In this multisite, real-world study, we showed that the 3-session ID PEP regimen provides robust long-term immunogenicity up to 10 years after initial PEP and ensures the induction of an adequate anamnestic response within 7 days after an additional booster in all participants.