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THYROID AND COVID-19
COVID-19 vaccination may not increase the risk of thyroid problems
BACKGROUND
Since December 2020, 15 vaccine candidates against SARS-CoV-2 to prevent COVID-19 infection have been approved to reduce infection and related hospitalizations and deaths. The rapid progress and limited follow-up data have generated public concerns about the safety of COVID-19 vaccines. Recently, thyroiditis, Graves’ disease, and hypothyroidism following COVID-19 vaccination have been described in a few case studies. Nevertheless, the effects of COVID-19 vaccines on thyroid function remain poorly understood. The current study aimed to characterize the association of mRNA and inactivated COVID-19 vaccines with the risk of thyroid dysfunction in the general population.
THE FULL ARTICLE TITLE
Wong CKH et al 2022 Risk of thyroid dysfunction associated with mRNA and inactivated COVID-19 vaccines: A population-based study of 2.3 million vaccine recipients. BMC Med 20:339. PMID: 36229814.
SUMMARY OF THE STUDY
This large population-based study obtained vaccine safety data by cross-linking electronic medical records from 2018 through 2021 with vaccination records of active patients from the Hong Kong Hospital Authority. The vaccine group included participants who received at least one dose of the CoronaVac (inactivated whole-virus) or BNT162b2 (viral mRNA) vaccine. Participants who received mixed COVID-19 vaccines, tested positive for COVID-19, or had thyroid problems within 3 years prior to the study were excluded.
The observation timeline consisted of a baseline period before vaccination, followed by a risk period (defined as the 56 days after vaccination), from February 2021 through September 2021. The number of events per 100,000 doses, and crude incidence rates per 100,000 person-years after each dose were calculated.
A total of 2,288,239 participants were included in the final analyses, consisting of 966,486 CoronaVac recipients and 1,321,753 BNT162b2 recipients. A total of 92.2% of CoronaVac recipients and 94.3% of BNT162b2 recipients received two vaccine doses. Overall, the risk of starting thyroid hormone therapy or developing either a decreased or increased TSH did not change significantly following either type of COVID-19 vaccination. Moreover, the risk of developing clinical thyroiditis or Graves’ disease did not change significantly following either type of COVID-19 vaccination. These findings were consistent by sex or age.
WHAT ARE THE IMPLICATIONS OF THIS STUDY?
In this largest vaccinated group analysis to date, there was no significant increase in the incidence of thyroid problems in the 56 days after COVID-19 vaccination by either the inactivated virus or by mRNA.
— Alan P. Farwell, MD
ATA THYROID BROCHURE LINKS
COVID-19 and the Thyroid: https://www.thyroid.org/covid-19/
Thyroiditis: https://www.thyroid.org/thyroiditis/
Graves’ Disease: https://www.thyroid.org/graves-disease/
ABBREVIATIONS & DEFINITIONS
Graves’ disease: the most common cause of hyperthyroidism in the United States. It is caused by antibodies that attack the thyroid and turn it on.
Thyroiditis: inflammation of the thyroid, most commonly cause by antibodies that attack the thyroid as seen in Hashimoto’s thyroiditis and post-partum thyroiditis. It can also result from an infection in the thyroid.
TSH: thyroid stimulating hormone — produced by the pituitary gland that regulates thyroid function; also the best screening test to determine if the thyroid is functioning normally.
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