Delayed HAV Vaccine Boosting

abstract & commentary

Synopsis: Patients who miss their booster dose of Havrix do not have to restart the series.

Source: Pappas VJ, Jr. Vaccine. 2001;19:339-402.

A question frequently asked of infectious
disease specialists is whether patients who received a single dose of Hepatitis A vaccine (Havrix, SmithKline Beecham Biologicals), but who missed the booster dose within 6-12 months, should repeat the series as recommended or proceed with a single booster dose. Pappas and colleagues assessed whether a delay in the administration of the booster dose of Havrix reduces the response rate. Two groups of patients were selected for study: 124 travelers who received either a single dose of Havrix 1440 IU or two doses of Havrix 720 IU more than 24 months earlier, and a control group of 125 travelers who received the primary dose of Havrix 1440 IU 6-12 months earlier. Subjects were matched by age and gender.

The median duration of time between receipt of their initial vaccine and enrollment was 35 months (range, 24-66 months) for those receiving delayed vaccination compared with 9 months (range, 6-14 months) for controls. HAV titers before and 30-40 days following the administration of a single booster dose of vaccine (1440 IU) were compared between groups.

Significantly fewer patients receiving delayed boosting had detectable HAV antibody levels (> 33 m IU/mL) at entry to study compared with controls (68% vs 89%; P < .001). Nonetheless, both groups responded equally well to a single booster dose of vaccine. There was no statistically significant difference in the geometric mean titers between the two groups in response to boosting.

Comment by Carol A. Kemper, MD, FACP

Receipt of a booster dose of Havrix up to 66 months after primary vaccination appears to be as successful as the recommended dosing schedule. Patients who miss their booster dose of Havrix do not have to restart the series. (Dr. Kemper is Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases, Stanford, Calif.)