Abstract:
Evidence suggests that rabies vaccine may have non-specific protective effects in animals and children.
We analyzed four years of data (2012–2015) from an observational study of the health and demographics
of a population of owned, free-roaming dogs in a low-income community in South Africa. The objective of
this analysis was to assess the association between rabies vaccine and all-cause mortality in dogs, stratified
by age group (0–3 months, 4–11 months, and 12 months and older), and controlling for the effects of
sex and number of dogs in the residence. Rabies vaccination reduced the risk of death from any cause by
56% (95% CI = 16–77%) in dogs aged 0–3 months, by 44% (95% CI = 21–60%) in dogs aged 4–11 months and
by 16% (95% CI = 0–29%) in dogs aged 12 months and older. We hypothesize that the protective association
between rabies vaccination status and all-cause mortality is due to a protective effect of rabies vaccine
against diseases other than rabies. Existence of a strong non-specific protective effect of rabies
vaccine on mortality in dogs would have implications for the design of dog rabies control programs that
aim to eliminate dog-mediated human rabies cases. Further, we propose that owned domestic dogs in
high mortality settings provide a useful animal model to better understand any non-specific protective
effect of rabies vaccine in children, due to dogs’ high numbers, high morbidity and mortality rates, relatively
short lifespan, exposure to a variety of infectious and parasitic diseases, and shared environment
with people.
