COVID-19 vaccines’ effect on thyroid conditions requires more study

If you’re a woman with a thyroid condition, could getting vaccinated against COVID-19 make it worse? 

That’s the claim in a Jan. 17 Instagram reel featuring a physical therapist who sells supplements and says the vaccine could exacerbate autoimmune or thyroid problems in people, especially women. The reel includes screenshots of scientific articles with headlines about whether there is a link between the vaccine and thyroid troubles. 

Text over the video reads: "Did the vaccine make your thyroid worse?" 

The short answer: The science is inconclusive about whether there’s a link between COVID-19 vaccines and worsening thyroid and autoimmune disorders. Experts told PolitiFact that no cause-and-effect relationship has been established between the two. 

Here’s what recent case studies have found:

• A 2022 case review study, published in the peer-reviewed Journal of Endocrinological Investigation, found that among 83 reported cases of thyroid disorder following COVID-19 vaccination, 68% were after vaccination with mRNA-based vaccines. 

"SARS-CoV-2 vaccines have been associated with very rare complications, such as thyroid disorders," according to the article. It also said that the vaccines’ benefits "exceed any risk of infrequent complications such as a transient thyroid malfunction."

• One 2023 review examined the case of a 50-year-old woman with no prior history of autoimmune or thyroid issues and no other health issues who reported developing a thyroid disorder after receiving the Pfizer COVID-19 vaccine. Blood tests confirmed the thyroid condition.  "The vaccine's mechanism of causing hypothyroidism is still being studied, but vaccines continue to improve, and the benefits outweigh the side effects," the study said.

• A separate 2023 case review said, "The causal relationship between COVID-19 vaccines and these autoimmune diseases remains to be demonstrated." 

"There is no evidence that COVID-19 vaccines cause thyroid disease," Dr. Robert H. Hopkins Jr., medical director of the National Foundation for Infectious Diseases, said in an email statement to PolitiFact.

Hopkins noted that millions of COVID-19 vaccines have been administered around the world, and serious adverse events are rare. 

"There have been rare reports of thyroid conditions occurring after COVID-19 vaccination in the medical literature. … These cases were identified anywhere from a few days to several weeks after vaccination and represented many different thyroid conditions," he said.

According to the American Thyroid Association, "There is no evidence at this time that having thyroid disease makes you at higher risk for vaccine-related problems."  

Dr. Michael McDermott, president of the American Thyroid Association and director of the University of Colorado Hospital’s endocrinology and diabetes practice, said in an email case reviews are "are good for bringing potential issues to the forefront of discussion (hypothesis generating) but scientifically are nowhere near adequate to establish cause and effect."  

He said much remains to be studied about how the COVID-19 virus and the vaccines affect thyroid disorders, McDermott said.

"Thyroid specialists are not yet able to determine the long-term consequences of COVID-19 infection. … The medical/scientific community needs to evaluate each new issue as it appears and thyroid dysfunction (temporary or permanent) is no exception."