Thyroid Disorders Can Be Caused or Worsened by COVID Shots
There have been a number of reports published in the medical literature describing cases of thyroid autoimmunity developing in individuals, who have received different types of COVID-19 shots.1 Cases occur in individuals who have never been diagnosed with a thyroid disorder and in those whose thyroid disorders worsen after COVID vaccinations.
The thyroid is an extremely important endocrine gland that regulates the majority of the body’s functions by producing and secreting hormones. Thyroid hormones play a fundamental role in regulating vital activities including growth, metabolism, reproduction and haematopoiesis. All cells in the body require energy to work optimally and, because the thyroid controls the metabolic rate and the process by which food is turned into energy, a properly functioning thyroid is integral to health.2 3
Most Cases of Autoimmune Thyroid Disorders Occur in Women After mRNA COVID Shots
A study published earlier this year in the journal Clinical Endocrinology and Metabolism warned clinicians of the potential onset or worsening of autoimmune thyroid disorders in genetically susceptible individuals after they have received a COVID shot. The study looked at 12 patients presenting at a Singapore clinic with Graves disease-related hypothyroidism, which developed or worsened after getting a COVID shot. Half of the patients had new symptoms of thyroid disease, while the other half experienced a relapse of old symptoms.4
Eleven of the 12 participants were women. The median age of the women was 35.5 years and the median time elapsed from the time the shot was given to manifestation of symptoms was 17 days. Five of the participants experienced clinical or biochemical hyperthyroidism after only one shot, while seven developed symptoms after the second dose with a median time onset of symptoms appearing within 21 days of vaccination.5
The study participants were given a booster COVID shot after developing or experiencing a worsening of an autoimmune thyroid disorder following COVID vaccinations. Researchers said:
In our case series, we observed that the exacerbation of hyperthyroidism can occur after the first or subsequent doses of the vaccine. Importantly, all the patients were able to tolerate a subsequent booster dose of SARS-CoV-2 mRNA vaccine without further exacerbation of hyperthyroidism.6
Another report in Frontiers in Public Health concluded that Graves disease could occur after getting a COVID shot. Researchers reviewed medical literature through August 2021 searching for a connection between the COVID shots and the onset of Graves disease finding five cases to study. The study authors hypothesized that the connection between COVID shots and thyroid disorders could lie in the fact that Pfizer/BioNTech’s BNT162b2 (now known as “Comirnaty”) mRNA biologic has four lipids, two if which are polyethylene glycol (PEG), “which may act as an adjuvant and induce an immune response in predisposed individuals, as there are rare reports of reactions to PEGs.”7
COVID Shots Can Cause Different Types of Thyroid Dysfunction
A study published in the Journal of Endocrinological Investigation in March 2022 demonstrated that of 83 reported cases of thyroid disorders following the administration of COVID shots, 68.7 percent occurred after mRNA-based shots, 15.7 percent after receipt of viral vectored COVID vaccines, and 14.5 percent after receipt of other inactivated COVID vaccines. Subacute thyroiditis developed in 60.2 percent of those who received a COVID shot; Graves disease in 25.3 percent; both subacute thyroiditis (SAT) and Graves disease in 2.4 percent; focal painful thyroiditis in 3.6 percent; silent thyroiditis in 3.6 percent; thyroid eye disease in 1.2 percent; overt hypothyroidism in 1.2 percent; atypical subacute thyroiditis 1.2 percent, and painless thyroiditis with TPP 1.2 percent.8
SAT is triggered by a viral infection or post viral inflammatory response in genetically susceptible individuals. 50 percent of the cases of SAT occurred after the BNT162b2 shot; 22 percent after Sinovac’s Coronovac COVID vaccine; 12 percent after the AstraZeneca/Oxford University’s AZD1222 (now known as “Vaxzevria”) COVID vaccine; 12 percent after the Moderna/NIAID’s mRNA-1273 (now known as “Spikevax”) COVID shot, and two percent after Bharat Biotech’s Covaxin COVID vaccine.
The majority—80 percent—of SAT sufferers post COVID shots were women with a median age of 39.5 years.9
Graves disease, an autoimmune disorder, occurs when agonist autoantibodies affecting the thyroid stimulating hormone receptor cause hyperthyroidism. 66.7 percent of the cases of Graves disease studied developed after the BNT162b2 shot; 19 percent after AZD1222; 9.5 percent after mRNA-1273 shot and 4.8 percent after Ad26.COV2.S.
Some 76.2 percent of the cases of Graves disease occurred in women with a median age of 44 years old.10
The researchers warned:
Just like infections, vaccines can play a role in the development of autoimmune diseases through various mechanisms, such as molecular mimicry, epitope spreading, polyclonal activation, bystander activation, and presentation of cryptic antigenic determinants.11
Genetically Susceptible Individuals at Risk for Thyroid Disease After COVID Shots
Researchers further explained that in certain populations of genetically susceptible people, the immune response to the vaccine antigen could extend to host cells exhibiting the similar self-antigen. This molecular mimicry between the vaccination antigen and thyroid proteins could cause an autoimmune response. The body could mount an immune response and attack thyroid cells ,as well as attack the SARS-CoV-2-related proteins post vaccination.
It has been shown that antibodies against SARS-CoV-2 S protein, as well as SARS-CoV-2 S protein, nucleoprotein, and membrane protein, cross-reacts with thyroid peroxidase. Many thyroid peroxidase gene sequences resemble gene sequences of SARS-CoV-2 proteins. Therefore, the production of antibodies against SARS-CoV-2 due to vaccination may play a role in the onset of autoimmune thyroiditis.12
Researchers point out the thyroid dysfunction post COVID shots could also result from the COVID biologic-derived S protein directly binding to ACE2-expressing thyroid cells, which would explain why thyroid disorders have developed after all types of COVID biologics. Other COVID biologic ingredients, including adjuvants, stabilizers, preservatives, and traces of antibiotics, could also contribute to disruption of thyroid function post COVID shots.13
The study authors speculate that it is likely that many more cases of Hashimoto’s thyroiditis have developed after COVID vaccination, but have not yet been identified because the autoimmune disease has a slow onset with hypothyroidism preceding the diagnosis by years. They call for further studies on the subject.14
The authors concluded:
The reports concerning the incidence rate of vaccination-induced autoimmune responses may be under-estimated. Because an effective monitoring system is missing, and the vaccination status of the majority of patients with newly diagnosed thyroid dysfunction is not checked. The world is currently undertaking the greatest mass vaccination, and cases of thyroid abnormalities will undoubtedly arise, either as a result of the vaccine-associated and/or vaccine-independent processes. Thus, prospective studies using vaccinated and unvaccinated groups should be conducted to establish a valid risk/benefit assessment and reliable figures of thyroid disorders.15
COVID Shots Linked to Increase in Anti-Thyroid Antibodies
A June 2022 study, which looked at the impact of the BNT162b2 and Coronavac shots on thyroid function, found that vaccination with these products was associated with a modest increase in anti-thyroid antibody titers, but had no significant increase on thyroid dysfunction. The study followed 215 adults, who received one of the COVID shots between June through August 2021 in a vaccination clinic in Hong Kong.16
Test subjects had blood tests to check the levels of their thyroid-stimulating hormone (TSH), free thyroxine (fT4), free triiodothyronine (fT3), anti-thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-Tg) antibodies prior to vaccination and again eight weeks post jab. Subjects were excluded from participating in the study if they had a history of pituitary/thyroid disorders; took any thyroid replacement or anti-thyroid medication or any other medication that could interfere with thyroid function; had an abnormal baseline thyroid test, or were pregnant.
The primary outcome of the study showed a modest yet significant increase in anti-TPO from 7.50 to 9.80 IU/ml and anti-TG from 12.24 to 15.7 IU/ml titers in subjects after receiving a COVID shot. Other thyroid function tests showed a statistically significant increase in free T4, along with statically significant decrease in free T3 resulting in a statistically significant decrease in the Free T4 and Free T3 ratio. Researchers concluded that this alteration in thyroid levels did not rise to the level needed to prove that overt thyroid dysfunction resulted from COVID vaccination.
More studies on the link between COVID vaccination and changes in thyroid function, including identification of genetically susceptible people and discussion of potential COVID shot risks with patients, would reduce the numbers of individuals developing thyroid dysfunction after vaccination.
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