BACKGROUND: To date, published data regarding long-lasting immunological rabies memory after a pre-exposure prophylaxis (PrEP)-schedule are scarce. We tested the hypothesis that rabies booster immunization elicits rapid anamnestic responses.

METHODS: For this observational study, we included participants who had received PrEP 10-24 years before inclusion. We measured rabies antibody titers before, and on days 3, 7 and 14 after one single intramuscular booster.

RESULTS: All 28 participants responded adequately regardless route of administration or (2-dose vs. 3-dose) PrEP-regimen.

CONCLUSION: Rabies immunological memory is reactivated within 7 days after a single intramuscular booster immunization, even when administered 10-24 years after PrEP.