OBJECTIVES: During the clinical development of a new intradermal influenza vaccine given using a microinjection system, in parallel with the conventional evaluation of vaccine reactogenicity, perception and acceptability of injection site reactions (ISR) were assessed using the VAPI© self-administered questionnaire developed and validated as previously described (Chevat et al, Health and Quality of Life Outcomes 2009, 7:21). METHODS: The questionnaire was specifically developed and validated according to recommended methods to assess vaccinees’ perception of ISR. It was completed 21 days after intradermal or intramuscular vaccination by elderly and non-elderly participants in two European, randomised, controlled, phase 3 trials. It was divided into 4 dimensions: “bother” (6 items), “arm movement” (4 items), “sleep” (4 items), “acceptability” (2 items), and 5 individual items: anxiety before and after vaccination, bother by pain during injection, satisfaction with injection system and willingness to be vaccinated again. Scores range from 1 to 5 (1 being the most favourable opinion). RESULTS: Of the 5,562 trial participants, 5,305 returned the questionnaire with at least one item completed. Mean scores were low (≤1.68 in non-elderly, ≤1.48 in elderly) in both vaccine groups, indicating that ISR did not bother participants or affect their sleep or arm movement (at least 75% were not at all affected). In the ID group, among those who answered the questions, 96% of non-elderly and 97% of elderly participants considered ISR caused by vaccination as being “totally” or “very” acceptable; 96% of both non-elderly and elderly participants were “very satisfied” or “satisfied” with the injection system; and 85% of non-elderly and 89% of elderly participants wanted to be vaccinated again. CONCLUSIONS: ISR were well accepted by participants, and were generally not a cause for concern. The level of satisfaction of the participants with the injection system was high, as was the willingness to be vaccinated again.