Needle-Syringe and Needle-Free Jet Injection Are Equally Effective for Flu Immunization

In 2011, the FDA instructed pharmacies to stop giving influenza shots with a previously approved needle-free jet injection device because little evidence showed that this delivery system provided adequate immunity against flu. Now, manufacturer-sponsored researchers have conducted an unblinded study in which 1250 adults seeking flu immunization at four hospital-employee health clinics were randomized to receive intramuscular doses of trivalent inactivated flu vaccine by either needle-free jet injector or traditional needle and syringe.

The needle-free injection system met all six predetermined noninferiority criteria (based on ratios of mean antibody titers and differences in seroconversion rates for each of the three virus strains in the va…