Clinical Manifestation of Subacute Thyroiditis Triggered by SARS-CoV-2 Infection Can Be HLA-Dependent

In the last two years, we have been struggling with the pandemic of SARS-CoV-2, the virus causing COVID-19. Several cases of subacute thyroiditis (SAT) have already been described as directly related to SARS-CoV-2 infection. The clinical course of SAT induced by SARS-CoV-2 can be entirely different from the classic SAT course, and one of the most important differences is a very rapid SAT onset observed in some patients, especially a phenomenon of the simultaneous presence of both diseases. The aim of this report is to compare HLA profile and clinical course of SAT in four patients, in whom SAT was considered as triggered by COVID-19, with special attention paid to the differences between a patient with rare simultaneous presence of SAT and COVID-19, and patients with longer time lag between the diseases. The unusual phenomenon of simultaneous occurrence of COVID-19 and SAT induced by SARS-CoV-2 infection can be HLA-dependent and related to the presence of homozygosity at HLA-B*35. Additionally, the clinical course of SAT triggered by COVID-19 can be HLA-related in regard to the risk of recurrence, and to a variety of other aspects, including severity of thyrotoxicosis.