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.