Low Risk for New-Onset Thyroid Diseases After mRNA Vaccines

NEW ORLEANS — The chance of new-onset thyroid disease after administration of mRNA COVID-19 vaccines was rare, but still noteworthy, according to a meta-analysis.

There were 77 cases of thyroid-related autoimmune diseases among people with no history of an autoimmune disease prior to receiving the COVID-19 vaccine, with 38 cases of Graves’ disease (GD) and 39 of subacute thyroiditis (SAT), reported Vikram Gill, MBBS, of St. Peter’s University Hospital/Rutgers University in New Brunswick, New Jersey.

Additionally, these autoimmune diseases occurred more often in women than in men, “about a 2-1 breakdown, which is what we would expect as women tend to have more autoimmune disease overall than men,” Gill said at a poster presentation at the American Association of Clinical Endocrinology annual meeting.

Specifically, 10 men were diagnosed with GD as were 28 women, while 13 and 26, respectively, were diagnosed with SAT. The average ages of men and women who developed post-vaccination autoimmune diseases were 41 and around 44, respectively.

“Our study doesn’t mean that these vaccines are not efficacious or are dangerous…it just means that these autoimmune disease may rarely emerge,” Gill said. “These patients did not have any autoimmune disorders before getting their vaccinations.”

Around 80% of people in the U.S. have received at least one dose of the COVID vaccine, while about 70% are considered full vaccinated, and more women than men have gotten vaccinated, according to CDC data. Previous research has shown links between COVID vaccination and autoimmune disorders, although other research has indicated that having a COVID-19 diagnosis increases the risk for these same disorders, but that vaccination can mitigate that risk.

Gill and co-author Hongxiu Luo, MD, also of St Peter’s, searched for articles reporting GD and SAT following COVID-19 mRNA vaccinations from 2019 to November 2023.

They found that a GD diagnosis happened about 40 days after the first dose, with SAT emerging sooner, at about 11 days after the first jab. In the group with GD, over half developed hyperthyroidism symptoms after the first dose of mRNA vaccine, while around 45% showed symptoms after dose 2. Roughly 5% showed signs after the third dose. In the SAT group, almost 54% showed hyperthyroidism symptoms after dose 1, as did about 44% after dose 2, and around 5% after dose 3.

“Interestingly, positive anti-TPO [anti-thyroid peroxidase] was only seen in five out 32 patients who were tested (15.6%), and 32 patients (74.4%) were negative for anti-TPO. Eleven out of 33 patients who were tested (33.3%) were positive for anti-Tg [antithyroglobulin], 22 patients (66.6 %) were negative,” Gill and Luo wrote.

Even if these vaccine-associated autoimmune diseases are not common, providers should be aware of these ties, Gill advised, adding that “the incidence is highest for the first dose.”

Samarth Virmani, MBBS, of Houston Methodist Hospital, told MedPage Today that the study was “interesting” and could inform vaccine development.

“While COVID now is somewhat in the past, this kind of study will help act as a basis for future vaccines that may come out in future pandemics,” said Virmani, who was not involved in the study.

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