Preservative-free influenza vaccine.

OBJECTIVE: To investigate the immunogenicity of and tolerance towards the preservative-free inactivated influenza vaccine Begrivac. METHODS: In this prospective, single-centre, non-controlled study, efficacy was evaluated by the change in influenza antibody titre from baseline to 21 days following vaccination. The safety variables included post-injection reactions and adverse events. Blood samples were taken on day 21 and the antibody titre assayed by haemagglutination inhibition test. RESULTS: All three of the European efficacy requirements for influenza vaccines are satisfied by the new preservative-free vaccine described in this report. The mean geometric increase in titre and the proportion of vaccination responders were greater in patients of the adult group than in the elderly. Thus for strain A/Beijing/262/95 66% of subjects seroconverted and 28% showed a significant increase in antibody titre (total 94%), compared to a total of 45 patients (76%) in the elderly group. For strain A/Sydney/5/97 the corresponding figures were total 55 (90%) adult and 47 (80%) elderly, and for B/Beijing/184/93 46 (75%) adult and 31 (53%) elderly. Sixty four subjects (53%) reported adverse events, mainly local reactions at the injection site such as pain, erythema and induration, and systemic reactions such as headache and fatigue. CONCLUSIONS: The absence of preservative in this novel vaccine preparation does not have any detectable impact on its efficacy or safety and tolerability profile.