Intramuscular versus intradermal administration of a recombinant hepatitis B vaccine: a comparison of response rates and analysis of factors influencing the antibody response.

In an open controlled study 286 health care workers in Stockholm, Sweden, received 20 micrograms of a recombinant hepatitis B vaccine (Engerix B) by the intramuscular route, and 383 2 micrograms by the intradermal route. Seroconversion to protective anti-HBs levels (anti-HBs titre greater than or equal to 10 IU/l) was achieved in 94% of the i.m. and 89% of the i.d. vaccinees. Female sex, intramuscular vaccination, young age, and being a non-smoker were associated with a higher response rate and a higher geometric mean anti-HBs titre than male sex, intradermal vaccination, old age and being a smoker. If an acceptable response rate to protective anti-HBs levels of 85% is chosen, intradermal vaccination can be used as a cost reducing strategy for all women and for non-smoking men less than 30 years of age, as estimated in a logistic regression model. Due to the variable antibody response in different individuals, post vaccination testing for anti-HBs titres is recommended in health care workers, regardless of vaccination route.