Patterns and outcomes of late onset thyroid disturbances after COVID-19 vaccination: A report of 75 cases.

Isolated cases of subacute thyroiditis exist in the early period of COVID-19 vaccination, largely after mRNA vaccines. Here we report late onset thyroid disturbances and persistent health issues in patients of thyroid disorders after COVID-19 vaccination. Seventy-five patients with post COVID-19 vaccination thyroid disturbances were identified. Among these, 41 had flare of underlying thyroid illness, majority occurring at a median time lag of 28.4 weeks since 2nd dose. Thirty-one cases of new onset hypothyroidism and three of new onset hyperthyroidism were reported, with a median time lag respectively of 17.2 and 22.6 weeks since 2nd dose. Most cases occurred after ChAdOx1-nCoV-19, which was the commonest vaccine employed in mass roll out in India. Significant improvement was observed in majority, after a median follow up of 22-26 weeks. New onset health issues persisting for ≥4 weeks were reported in 37.3% and were common in individuals with history of COVID-19 before vaccine. New onset metabolic, musculoskeletal, and reproductive disorders were the common health complaints. Active monitoring is warranted for late onset adverse events after COVID-19 vaccines of all types. Larger studies with involvement of unvaccinated individuals are required to understand the incidence and causality of late onset thyroid disturbances after COVID-19 vaccines.