Subacute thyroiditis after seasonal influenza vaccination

We report the first patient with subacute thyroiditis after influenza vaccination in Japan. A 49-year-old woman received a seasonal influenza vaccination in October 2009. She also received a seasonal influenza vaccination in 2008. After the vaccination, she experienced spontaneous pain and tenderness in the right lower neck. Together with the results of laboratory examinations and thyroid echography, we established the diagnosis of subacute thyroiditis. The patient had human leukocyte antigens (HLAs) of A2/A11 and B62/B35. HLA-A2-positive is reported at a risk of interferon-alpha-induced autoimmune thyroid disorder, and HLA-B35-positive is reported at a risk of subacute thyroiditis. Since fever and cervical pain are reported as adverse effects of influenza vaccination, subacute thyroiditis after influenza vaccination might have been missed.