Most vaccines are delivered by the intramuscular or subcutaneous routes.  The intradermal route is only used for the administration of BCG and rabies vaccines.

There is now a renewed interest in intradermal vaccine delivery because the dermis and epidermis of human skin are rich in antigen-presenting cells, suggesting that delivery of vaccines to these layers, rather than to muscle or subcutaneous tissue, should be more efficient and induce protective immune responses with smaller amounts of vaccine antigen.

The recent PATH and WHO report reviewed more than 90 clinical trials of intradermal delivery with vaccines against 11 diseases.

For influenza and rabies vaccines, intradermal delivery of reduced doses resulted in equivalent immune responses to the standard dose delivered by the standard route. Data from trials with hepatitis B vaccine were encouraging and promising data was obtained with inactivated poliovirus, yellow fever and hepatitis A vaccines.

Take home messages

1. Live-attenuated vaccines have been successfully delivered intradermally and should be good candidates for intradermal delivery.
2. Reduced doses of inactivated whole-virion vaccines, such as rabies and inactivated poliovirus vaccines, have shown satisfactory immunogenicity when delivered intradermally.
3. Inactivated whole-virion influenza vaccine is suitable as it has intrinsic immune-stimulating sequences, which might avoid the need for additional adjuvants.
4. There are no published clinical data regarding intradermal delivery of polysaccharide conjugate vaccines, which include meningococcal and pneumococcal conjugate vaccines.
5. Vaccines that contain aluminum-based or oil-in-water adjuvants are likely to have unacceptable local reactogenicity following intradermal administration.
6. A trial compared the currently recommended regimen of 20 micrograms of hepatitis B surface antigen (HBsAg) intramuscularly on days 0, 30, and 180, with a more economical regimen of 2 micrograms of HBsAg intradermally on days 0, 30, and 180. This trial was performed in 50 seronegative health care workers. There was no significant difference in seroconversion between the intradermal group (96%) and the intramuscular group (100%). Data demonstrate that 0.1 mL of inactivated hepatitis B virus vaccine (Heptavax-B) intradermally is immunogenic in healthy adults. (JAMA)

Dr KK Aggarwal

Padma Shri Awardee

President Confederation of Medical Associations in Asia and Oceania (CMAAO)

Group Editor-in-Chief IJCP Publications

President Heart Care Foundation of India

Past National President IMA