When we will say good-bye to rabies NTV?

Sir David Semple developed sheep-brain vaccine for human use in 1911 in India. Since then, technological advances have produced less reactogenic nerve-tissue vaccine (NTV) such as suckling mouse brain vaccine. This historical vaccine served its purpose for almost 100 years when there was no better and affordable technology for rabies endemic countries. However, tissue-culture technology developed a few decades ago has completely revolutionalized vaccine production and changed the concept of biological testing. There is now a global consensus to minimize the use of laboratory animals for biological research and biological testing and to follow strict ethical procedures for unavoidable use of laboratory animals. The World Health Organization (WHO) also strongly recommends discontinuation of the old nerve tissue vaccines because these vaccines have a high rate of adverse reactions and lower efficacy. It is unethical to use innocent animals for production of traditional rabies vaccine using century old technology in the name of human welfare when tissue-culture technology is available and cost-effective rabies vaccine technique has been developed as an alternative.

Nerve-tissue vaccine has also been produced for dog immunization and post-exposure vaccination of food and companion animals in many countries in the past but it has been phased out due to economic and technical reasons in most rabies endemic countries.

Following the WHO recommendation in 1984 to replace NTVs, many Asian countries have discontinued the production and use of nerve-tissue vaccines for human use. In 2004, the WHO Expert Consultation issued a definitive statement to the effect that NTVs should be discontinued and that only rabies vaccine of tissue-culture origin or embryonated egg origin should be used in humans. Most rabies endemic Asian countries have phased out production and use of NTV over last 20 years, namely China (1990), Thailand (1992), Sri Lanka (1995), Indonesia (1996), Philippines (1997), Lao PDR (2005), Cambodia (2005), India (2005), Nepal (2006), Vietnam (2007) and most recently Bangladesh (2011).

Pakistan has agreed in principle to end NTV production by 2012, but an alternative such as the bulk purchase of concentrated rabies vaccine remains to be worked out. In Myanmar, human rabies vaccine is produced by the Myanmar Pharmaceutical Company but the buyer is the Ministry of Health. The situation needs advocacy and an alternative solution to reduce the cost of vaccination.

Due to the cost of production and strict international quality control requirements, most rabies endemic countries are not currently producing their own human rabies vaccines.  However, the multisite Intradermal (I/D) vaccination schedule is a cost-effective, scientifically proven and WHO recommended vaccination schedule. It is widely practiced in Thailand, Sri Lanka, the Philippines, India and Bangladesh. WHO is encouraging rabies endemic countries to introduce this cost-effective rabies vaccination schedule to improve availability, affordability and accessibility of modern rabies vaccine. Economic post-exposure rabies prophylaxis using the intradermal route is a viable alternative for NTV delivered by the public sector in rabies endemic countries.

Contributed by Dr Gyanendra  Gongal, Scientist, Disease Surveillance and Epidemiology, WHO Regional Office for South East Asia, New Delhi