Older adults and non-response to rabies post-exposure prophylaxis: Challenges and approaches

Rabies vaccines are highly effective and immunogenic in most populations, including when used as rabies post-exposure prophylaxis (RPEP); however, there is mounting evidence that the immune response to rabies vaccines, though predicted to be adequate, may be lower in older adults. Despite this, there are no specific recommendations in Canadian guidance to monitor the serological response of older adults following RPEP. Furthermore, while Canadian guidance recommends the intramuscular route for RPEP vaccination, there is good evidence supporting the immunogenicity, effectiveness and safety of RPEP vaccination using the intradermal route. We present a case of an 87-year-old male with rabies exposure who failed to respond to two series of RPEP with intramuscular rabies vaccination but responded to a third series using intradermal vaccine administration and provide reasoning for subsequent management. This case is brought forward to prompt discussion and research as to the utility of completing serology in older adults receiving RPEP as well as vaccination strategies, including route of administration, in those who do not respond to an initial course of RPEP vaccination.