Rabies vaccination is required by law in nearly all areas. Even though protection from rabies is documented to last at least three years, current law in some states or areas still requires that boosters be given annually or biannually rather than the standard policy of every three years. However, vaccination against rabies virus is occasionally associated with debilitating adverse effects. According to the CDC domestic animals account for less than 10% of the reported rabies cases, with cats, cattle, and dogs most often reported rabid. Scientific data indicate that vaccinating dogs against rabies every three years, as most states require, is unnecessary.
It has been common practice since the development of canine vaccines in the late 1950’s to administer them annually. The recommendation to vaccinate annually was based on the assumption that immunity would wane in some dogs, thus to ensure immunity in the population, all dogs required revaccination since it was not practical to test each animal for antibody. Little or no research has been done to demonstrate that the practice of annual revaccination has any scientific value in providing greater immunity than would be present if an animal was never revaccinated or was revaccinated at intervals longer than one year.
Rabies remains a serious and usually fatal disease in many countries. The World Health Organization (WHO) estimates that approximately 10 million people worldwide require medical treatment against rabies each year after being exposed to an animal suspected of having rabies. In the United States of America (USA), there are close to 40,000 post-exposure prophylaxis treatments administrated each year, which represents about 100 million dollars in costs for treatment, health care, education and prevention. Current rabies exposure immune prophylaxis includes a new treatment product tested in Phase 2 and 3 clinical trials in Israel. This product is now sold in 10 countries and should soon be available in the USA. Results of comparison clinical trials show it to be as efficacious as other human immunoglobulin G (IgG) products. In animals, there have been no documented cases in North America of rabies in vaccinated, truly immunized dogs and cats for two decades, although the disease still exists among wildlife and feral companion animal species. While most pet dogs are vaccinated for rabies, fewer cats have historically been vaccinated until recent laws have required it. The Rabies Challenge Fund (RCF) research studies are now at years 6 and 7 post-vaccination, and the initial challenge phase results showed the vaccinates to be protected from rabies.
Vaccination can provide an immune response that is similar in duration to that following a natural infection. In general, adaptive immunity to viruses develops earliest and is highly effective. Such anti-viral immune responses often result in the development of sterile immunity and the duration of immunity (DOI) is often lifelong. In contrast, adaptive immunity to bacteria, fungi or parasites develops more slowly and the DOI is generally short compared with most systemic viral infections. Sterile immunity to these infectious agents is less commonly engendered.