Adverse events after Fluzone ® Intradermal vaccine reported to the Vaccine Adverse Event Reporting System (VAERS), 2011-2013

Background: In May 2011, the first trivalent inactivated influenza vaccine exclusively for intradermal administration (TIV-ID) was licensed in the US for adults aged 18-64 years.

Objective: To characterize adverse events (AEs) after TIV-ID reported to the US Vaccine Adverse Event Reporting System (VAERS), a spontaneous reporting surveillance system.

Methods: We searched VAERS for US reports after TIV-ID among persons vaccinated from July 1, 2011-February 28, 2013. Medical records were requested for reports coded as serious (death, hospitalization, prolonged hospitalization, disability, life-threatening-illness), and those suggesting anaphylaxis. Clinicians reviewed available information and assigned a primary clinical category to each report. Empirical Bayesian data mining was used to identify disproportional AE reporting following TIV-ID. Causality was not assessed.

Results: VAERS received 466 reports after TIV-ID; 9 (1.9%) were serious, including one reported fatality in an 88-year-old vaccinee. Median age was 43 years (range 4-88 years). The most common AE categories were: 218 (46.8%) injection site reactions; 89 (19.1%) other non-infectious (comprised mainly of constitutional signs and symptoms); and 74 (15.9%) allergy. Eight reports (1.7%) of anaphylaxis were verified by the Brighton criteria or a documented physician diagnosis. Disproportional reporting was identified for three AEs: 'injection site nodule', 'injection site pruritus', and 'drug administered to patient of inappropriate age'. The findings for the first two AEs were expected. Twenty-four reports of vaccinees <18 years or ≥ 65 years were reported, and 14 of 24 were coded with the AE 'drug administered to patient of inappropriate age'.

Conclusions: Review of VAERS reports did not identify any new or unexpected safety concerns after TIV-ID. Injection site reactions were the most commonly reported AEs, similar to the pre-licensure clinical trials. Use of TIV-ID in younger and older individuals outside the approved age range highlights the need for education of healthcare providers regarding approved TIV-ID use.