The challenges of vaccinating against rabies in hot countries
According to the World Health Organization (WHO), human rabies is present in 150 countries and territories all over the world. In 2005, an article published in the Bulletin of the WHO estimated the human mortality from endemic canine rabies to be 55,000 deaths per year. More than 99% of these deaths occurred in the developing world. That is why the rabies vaccine is recommended for “some high risk populations” in the WHO Model List of Essential Medicines.
In 2015, WHO, the World Organisation for Animal Health (OIE), the Food and Agriculture Organization of the United Nations (FAO) and the Global Alliance for Rabies Control (GARC) established a global “United Against Rabies” collaboration to form a common strategy to achieve "Zero human rabies deaths by 2030"1.
Dogs are the main source of rabies transmission. Vaccinating dogs and preventing dog bites could eliminate rabies, and a campaign of mass canine vaccination is programmed in developing countries. For example, 730,633 dogs have been vaccinated in India and Tanzania since 2013 through a project called Mission Rabies.
Nevertheless, maintaining the cold chain for vaccines in hot countries is a significant challenge, since their temperature must be between 2°C and 8°C, according to WHO recommendations. A test conducted by Mission Rabies and Timestrip, a company providing temperature monitoring solutions, showed that around one third of the teams participating reported that vaccines were exposed to temperatures above 30°C for more than 4 hours. On nine occasions, temperature drops to 0°C or below were also reported.
But a recent study showed that a commonly used rabies vaccine produces the same level of protective antibodies in dogs after being stored for six months at 25°C and for three months at 30°C, a quite encouraging result for this campaign to eradicate rabies.
1See WHO fact sheet following this link.