Abstract
WHO recommends that children living in highly endemic regions be considered for pre-exposure prophylaxis with rabies vaccine, since they will be at continual, frequent or increased risk of exposure to the animal bites.Citation1 The recommendations will come from WHO only after it has been proven by many previous scientific studies among children which have shown that pre-exposure prophylaxis using Purified Chick Embryo Cell Vaccine (PCECV) is safe and well tolerated.Citation2-Citation4 This has been mentioned in the discussion. The authors have not claimed/nor assumed in any part of their manuscript that they are the first to demonstrate the safety of purified chick embryo cell rabies vaccine when administered by intradermal route for pre-exposure prophylaxis against rabies in children.
The study vaccine already was evaluated for safety and immunogenicity in other clinical trials conducted in India as pre- and post-exposure prophylaxis both by intramuscular and intradermal route and found to be safe and immunogenic.Citation5-Citation7 Immunogenicity has been studied by assessing RVNA by RFFIT at a WHO collaborating center for research on rabies. This has been mentioned in the Introduction.
The objective of the study has been clearly mentioned as to assess the safety of a post- marketed/licensed rabies vaccine. This has been mentioned in the Introduction. Safety reporting is the cornerstone of most post-licensure safety monitoring systems because of the ability to capture unexpected events.Citation8 The authors also knew that immunogenicity can be studied by assessing the rabies virus neutralizing antibodies by RFFIT, as the corresponding author has more than 10 published studies in international journals including more than 5 publications from 2005 onwards in the Human Vaccine and Immunotherapeutics journal in the field of rabies vaccination including assessment of RVNA at a WHO collaborating center on research.
In conclusion, it could not be pertinent to decide on the safety of PCEC vaccine by investigating antibody response to vaccine, which is a measure of immunogenicity. These two are different issues, and have to be studied appropriately with sound scientific knowledge/ research experience in the field of rabies vaccine.
Disclosure of Potential Conflicts of Interest
No potential conflicts of interest were disclosed.
References
- World Health Organization. WHO expert consultation on rabies. TRS 982. WHO, Geneva 2013.
- Lang J, Duong GH, Nguyen VG, Le TT, Nguyen CV, Kesmedjian V, Plotkin SA. Randomised feasibility trial of pre-exposure rabies vaccination with DTP-IPV in infants. Lancet 1997; 349:1663 - 5; http://dx.doi.org/10.1016/S0140-6736(96)10085-4; PMID: 9186385
- Shanbag P, Shah N, Kulkarni M, Juvekar M, Madhusudana SN, Vakil HB, Malerczyk C. Protecting Indian schoolchildren against rabies: pre-exposure vaccination with purified chick embryo cell vaccine (PCECV) or purified verocell rabies vaccine (PVRV). Hum Vaccin 2008; 4:365 - 9; http://dx.doi.org/10.4161/hv.4.5.5987; PMID: 18398307
- Kamoltham T, Thinyounyong W, Phongchamnaphai P, Phraisuwan P, Khawplod P, Banzhoff A, et al. Preexposure rabies vaccination of children in Thailand using Purified Chick Embryo Cell Rabies Vaccine intra dermally is immunogenic and safe. J Pedod 2007; 151:173 - 7; http://dx.doi.org/10.1016/j.jpeds.2007.02.044
- A clinical evaluation of safety and immunogenicity of purified chick embryo cell rabies vaccine (Vaxirab N) administered intradermally as pre exposure prophylaxis in healthy volunteers. 2010, India.
- A clinical evaluation of safety and immunogenicity of purified chick embryo cell rabies vaccine (Vaxirab N) administered intramuscularly as post exposure prophylaxis in animal bite cases. 2011, India.
- A clinical evaluation of safety and immunogenicity of purified chick embryo cell rabies vaccine (Vaxirab N) administered intradermally as post exposure prophylaxis in animal bite cases. 2011,India.
- World Health OrganizationVaccine safety basics post-licensure vaccine safety. [Internet]. Geneva: WHO Press; Available from: http://www.who.int/vaccine_safety/initiative/tech_support/Vaccine-safety-E-course-manual.pdf