To the Editor.
—The review of hepatitis A prevention in travelers by Dr Steffen and colleagues1 mentions the recently introduced vaccine based on the strain HM 175 (Havrix, SmithKline Beecham Biologicals, Rixensart, Belgium), usually administered at a dose of 720 enzyme-linked immunosorbent assay (ELISA) units. A dose of 1440 ELISA units is also mentioned.It has not been shown that a dose of 1440 units provides more protection than a dose of 720 units; published studies examining protective efficacy used 360 or 720 units. At best, the added benefit will be small. More importantly, the safety of a 1440-unit vaccine has not been adequately studied. Its use has been described in three publications.In a study by Just and Berger,2 60 subjects received the 1440-unit vaccine and no serious adverse effects were reported. The extent of monitoring was self-reporting and liver enzyme testing. In a study by Jilg
Lonergan G. Hepatitis A Vaccine: Which Dose Is Best?. JAMA. 1995;273(13):999. doi:10.1001/jama.1995.03520370039029