Updates-By Carol A. Kemper, MD, FACP

Delayed HAV Vaccine Boosting

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 nine 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 < 0.001). 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. 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.

Fewer Unrecognized HCV Infections

Source: Pappas VJ, Jr. Hepatitis Control Report 2000;5:3-6.

The hepatitis c lookback pro-gram begun by the U.S. Department of Health and Human Services in 1998 has, thus far, identified far fewer cases than anticipated of previously unrecognized hepatitis C virus (HCV) infection. The intent of the program was to trace recipients of contaminated blood products obtained from infected donors before the availability in 1992 of improved HCV screening using the second-generation Chiron assay.

The CDC estimates that 94,906 individuals who donated blood between 1988 and 1992, who subsequently tested positive for HCV infection after July 1992, will have been identified by the program by the end of 2000. Based on this information, ~100,000 recipients of those donated products will be traced and contacted, resulting in the notification of an estimated 1520 individuals who were previously unaware of their HCV infection.

These figures are significantly lower than those originally estimated. Initial calculations suggested that up to 500,000 people could have potentially received blood from infected donors. The actual figures were lower because donors donated less frequently than expected (twice vs estimated 3-5 times/donor), and fewer components were used per donation (2 vs estimated 6-10/donation). In addition, centers that used hepatic transaminase as a surrogate marker were able to screen out a greater number of infected donations than anticipated. These data indicate there are probably far fewer cases of previously unrecognized HCV infection in the United States than public health figures feared—good news for the public but not such good news for the pharmaceutical industry.

Quinidine: Check Your Formulary

Source: MMWR Morb Mortal Wkly Rep 2000;49:1138-1140.

The availability of newer anti-microbial agents has brought welcome change to many hospital formularies. But, as an Infectious Disease (ID) specialist, how often do formulary changes for cardiac drugs catch your eye?

This report from the Centers for Disease Control indicates that newer anti-arrhythmics are, in some hospitals, replacing quinidine gluconate on their formularies. The unintended consequence may be the lack of availability of this critical agent for the treatment of malaria due to P. falciparum. Quinidine gluconate is the only parenteral agent in the United States indicated for use in the treatment of patients with complicated or life-threatening malaria, including those who are unable to tolerate oral therapy, who have high levels of parasitemia, and those with altered mental status or renal failure.

ID specialists should check with their hospital pharmacies to ensure ready availability of this agent, or at least have the pharmacist identify a dependable source in case of emergencies. Physicians who have difficulty securing an immediate supply of the drug can contact the Eli Lilly Company (800-821-0538, 24 hours a day), or the CDC malaria hotline (daytime number 770-488-7788; after hours, request the on-call person for malaria be paged).