Can you get more out of the flu vaccine?

New techniques not possible this year

Faced with a severe shortage of influenza vaccine, it’s tempting to get as much as you can out of your doses. But two techniques that could extend flu vaccine are not recommended for use, according to officials of the Centers for Disease Control and Prevention (CDC).

A study in healthy adults indicates that a half- dose of flu vaccine could be effective.1 But Lance Rodewald, MD, director of CDC’s Immunization Services Division, noted the vaccine is needed for chronically ill and other high-risk people, in whom the smaller dose has not been tested. Further studies are under way, holding out the possibility that the vaccine supply could be extended in future years, he says. "At this time, it’s not a viable option."

Meanwhile, Becton Dickinson of Franklin Lakes, NJ, announced it had a supply of special syringes that reduce waste and could increase doses available in multidose vials by up to 10%. However, those, too, are not ready for use in the United States for "regulatory, liability, and biologic reasons," he says.

If there is some vaccine remaining in the vial, but not enough for a full dose, the person administering the vaccine may be tempted to obtain the remainder from another vial, Rodewald notes. That could lead to cross-contamination of vials and could make it difficult to trace adverse events because the vials may be from different lots, he says.

Also, a per-dose excise tax funds the National Vaccine Injury Compensation program and leaves open the possibility that people vaccinated with the 11th dose would not be covered, Rodewald explains. And the syringes currently available aren’t safety-engineered, which violates the bloodborne pathogens standard of the U.S. Occupational Safety and Health Administration.

"We really looked at it hard," he adds. "It raises a number of issues that could be problematic."


1. Treanor J, et al. Evaluation of a single dose of half strength inactivated influenza vaccine in healthy adults. Vaccine 2002; 20:1,099-1,105.