Risk of thyroid dysfunction associated with mRNA and inactivated COVID-19 vaccines: a population-based study of 2.3 million vaccine recipients

SARS-CoV-2-Vaccine-Related Endocrine Disorders: An Updated Narrative Review

The emergence of the COVID-19 pandemic has led to the rapid and worldwide development and investigation of multiple vaccines. While most side effects of these vaccines are mild and transient, potentially severe adverse events may occur and involve the endocrine system. This narrative review aimed to explore the current knowledge on potential adverse endocrine effects following COVID-19 vaccination, with thyroid disorders being the most common. Data about pituitary, adrenal, diabetes, and gonadal events are also reviewed. This review also provides a comprehensive understanding of the pathogenesis of endocrine disorders associated with SARS-CoV-2 vaccines. PubMed/MEDLINE, Embase database (Elsevier), and Google Scholar searches were performed. Case reports, case series, original studies, and reviews written in English and published online up to 31 August 2023 were selected and reviewed. Data on endocrine adverse events of SARS-CoV-2 vaccines are accumulating. However, their causal relationship with COVID-19 vaccines is not strong enough to make a definite conclusion, and further studies are needed to clarify the pathogenesis mechanisms of the endocrine disorders linked to COVID-19 vaccines.

The impact of the SARS-CoV2 pandemic on the prescription of thyroid medication in Austria - A nationwide population-based registry analysis

BACKGROUND

Case reports indicate a clinical connection between SARS-CoV-2 and thyroid dysfunctions. However, evidence from large population-based registry analyses is sparse, especially in Europe, where iodine deficiency is common. This study aimed to analyze the impact of the COVID-19 pandemic on healthcare provision for thyroid diseases in Austria.

METHODS

We performed a retrospective, population-based registry analysis of the Austrian health insurance fund database, covering more than 9 million inhabitants. Data from all patients with prescriptions of thyroid-specific drugs and/or inpatient thyroid-related diagnoses from 2017 to 2019 (pre-pandemic years) were compared to 2020 and 2021 (pandemic years; characterized by high numbers of SARS-CoV2 infections and population-wide vaccination strategy). The incidence rates of thyroid medication prescriptions for hypothyroidism and hyperthyroidism were calculated for every year to evaluate the impact of the pandemic.

RESULTS

The incidence rate for total thyroid medication prescription was 539.07/100,000 individuals (534.23-543.93 95%CI) in 2018 and declined during the pandemic (2020: 387.19/100,000 (383.12-391.29 95%CI); 2021: 336.90/100,000 (333.11-340.73 95%CI)). Similarly, the incidence rate for levothyroxine prescription was higher pre-pandemic (2018: 465.46/100,000 (460.97-469.98 95%CI) and declined during the pandemic (2020: 348.14/100,000 (344.28-352.03 95%CI); 2021: 300.30/100,000 (296.7-303.91 95%CI). The incidence rates of thiamazole prescriptions (2018: 10.24/100,000 (9.58-10.93 95%CI); 2020: 8.62/100,000 (8.03-9.26 95%CI); 2021: 11.17/100,000 (10.49-11.89 95%CI) were stable.

CONCLUSIONS

These findings suggest no clinically significant impact of SARS-CoV2 and/or vaccination on thyroid function at a population level.

Risk of Incident Thyroid Dysfunction in the Post-Acute Phase of COVID-19: A Population-Based Cohort Study in Hong Kong

OBJECTIVE

The evidence of thyroid dysfunction in the post-acute phase of SARS-CoV-2 infection is limited. This study aimed to evaluate the risk of incident thyroid dysfunction in the post-acute phase of COVID-19.

METHODS

This retrospective, propensity-score matched, population-based study included COVID-19 patients and non-COVID-19 individuals between January 2020 and March 2022, identified from the electronic medical records of the Hong Kong Hospital Authority. The cohort was followed up until the occurrence of outcomes, death, or 31 January 2023, whichever came first. Patients with COVID-19 were 1:1 matched to controls based on various variables. The primary outcome was a composite of thyroid dysfunction (hyperthyroidism, hypothyroidism, initiation of antithyroid drug or levothyroxine, and thyroiditis). Cox regression was employed to evaluate the risk of incident thyroid dysfunction during the post-acute phase.

RESULTS

A total of 84 034 COVID-19 survivors and 84 034 matched controls were identified. Upon a median follow-up of 303 days, there was no significant increase in the risk of diagnosed thyroid dysfunction in the post-acute phase of COVID-19 (hazard ratio [HR] 1.058, 95% confidence interval 0.979-1.144, P = .154). Regarding the secondary outcomes, patients with COVID-19 did not have increased risk of hyperthyroidism (HR 1.061, P = .345), hypothyroidism (HR 1.062, P = .255), initiation of antithyroid drug (HR 1.302, P = .070), initiation of levothyroxine (HR 1.086, P = .426), or thyroiditis (P = .252). Subgroup and sensitivity analyses were largely consistent with the main analyses.

CONCLUSION

Our population-based cohort study provided important reassuring data that COVID-19 was unlikely to be associated with persistent effects on thyroid function.

Thyroid dysfunction in COVID-19

The COVID-19 pandemic has affected over 772 million people globally. While lung damage is the major contributor to the morbidity and mortality of this disease, the involvement of multiple organs, including the endocrine glands, has been reported. This Review aims to provide an updated summary of evidence regarding COVID-19 and thyroid dysfunction, incorporating highlights of recent advances in the field, particularly in relation to long COVID and COVID-19 vaccination. Since subacute thyroiditis following COVID-19 was first reported in May 2020, thyroid dysfunction associated with COVID-19 has been increasingly recognized, secondary to direct and indirect effects on the hypothalamic-pituitary-thyroid axis. Here, we summarize the epidemiological evidence, pattern and clinical course of thyroid dysfunction following COVID-19 and examine radiological, molecular and histological evidence of thyroid involvement in SARS-CoV-2 infection. Beyond acute SARS-CoV-2 infection, it is also timely to examine the course and implication of thyroid dysfunction in the context of long COVID owing to the large population of survivors of COVID-19 worldwide. This Review also analyses the latest evidence on the relationship between the therapeutics and vaccination for COVID-19 and thyroid dysfunction. To conclude, evidence-based practice recommendations for thyroid function testing during and following COVID-19 and concerning COVID-19 vaccination are proposed.

Hyperthyroidism

Thyrotoxicosis causes a variety of symptoms and adverse health outcomes. Hyperthyroidism refers to increased thyroid hormone synthesis and secretion, most commonly from Graves' disease or toxic nodular goitre, whereas thyroiditis (typically autoimmune, viral, or drug induced) causes thyrotoxicosis without hyperthyroidism. The diagnosis is based on suppressed serum concentrations of thyroid-stimulating hormone (TSH), accompanied by free thyroxine and total or free tri-iodothyronine concentrations, which are raised (overt hyperthyroidism) or within range (subclinical hyperthyroidism). The underlying cause is determined by clinical assessment, detection of TSH-receptor antibodies and, if necessary, radionuclide thyroid scintigraphy. Treatment options for hyperthyroidism include antithyroid drugs, radioactive iodine, and thyroidectomy, whereas thyroiditis is managed symptomatically or with glucocorticoid therapy. In Graves' disease, first-line treatment is a 12-18-month course of antithyroid drugs, whereas for goitre, radioactive iodine or surgery are preferred for toxic nodules or goitres. Evidence also supports long-term treatment with antithyroid drugs as an option for patients with Graves' disease and toxic nodular goitre.

Increased Risk of Thyroid Eye Disease Following Covid-19 Vaccination

CONTEXT

SARS-CoV-2 infection and Covid-19 vaccines have been associated with thyroid disorders.

OBJECTIVE

We analyzed the risk of thyroid eye disease (TED) following Covid-19 vaccination. This was a self-controlled case series study at a tertiary referral center for TED. A total of 98 consecutive patients with newly developed (n = 92) or reactivated (n = 6) TED occurring between January 1, 2021, and August 31, 2022, were included. TED was assessed in patients undergoing Covid-19 vaccination. Person-days were defined as exposed if TED occurred 1 to 28 days after vaccination, and unexposed if occurring outside this time window. Conditional Poisson regression models were fitted to calculate incidence rate ratio (IRR) and 95% CI of exposed vs unexposed. Sensitivity analyses were conducted considering different exposed periods, and effect modification by potential TED risk factors.

RESULTS

Covid-19 vaccines were administered in 81 people, 25 (31%) of whom developed TED in exposed and 56 (69%) in unexposed periods. The IRR for TED was 3.24 (95% CI 2.01-5.20) and 4.70 (95% CI 2.39-9.23) in patients below 50 years of age. Sex, smoking, and radioiodine treatment did not modify the association between TED and vaccination. TED risk was unrelated to the number of vaccine doses, and progressively decreased over time following vaccination (P trend = .03).

CONCLUSION

The risk of TED was significantly increased after Covid-19 vaccination, especially in people below 50 years of age. Possible mechanisms include spike protein interaction with the angiotensin-converting enzyme II receptor, cross-reactivity with thyroid self-proteins, and immune reactions induced by adjuvants. We suggest monitoring of individuals undergoing Covid-19 vaccination, especially if young and at risk for autoimmunity.

Immune-related adverse events and disease outcomes after the third dose of SARS-CoV-2 mRNA-BNT162b2 vaccine in cancer patients receiving immune checkpoint inhibitors

BACKGROUND

The clinical implications of the third dose of coronavirus disease 2019 (COVID-19) vaccines in patients receiving immune checkpoint inhibitors are currently unknown. We performed a prospective analysis of the Vax-On-Third study to investigate the effects of antibody response on immune-related adverse events (irAEs) and disease outcomes.

METHODS

Recipients of the booster dose of SARS-CoV-2 mRNA-BNT162b2 vaccine who had received at least one course of an anti-PD-1/PD-L1 treatment before vaccination for an advanced solid malignancy were eligible.

RESULTS

The current analysis included 56 patients with metastatic disease (median age: 66 years; male: 71%), most of whom had a lung cancer diagnosis and were being treated with pembrolizumab- or nivolumab-based regimens. The optimal cut-point antibody titer of 486 BAU/mL allowed a dichotomization of recipients into low-responders (Low-R, < 486 BAU/mL) or high-responders (High-R, ≥ 486 BAU/mL). After a median follow-up time of 226 days, 21.4% of patients experienced moderate to severe irAEs without any recrudescence of immune toxicities preceding the booster dose. The frequencies of irAE before and after the third dose did not differ, but an increase in the cumulative incidence of immuno-related thyroiditis was observed within the High-R subgroup. On multivariate analysis, an enhanced humoral response correlated with a better outcome in terms of durable clinical benefit, which resulted in a significant reduction in the risk of disease control loss but not mortality.

CONCLUSIONS

Our findings would strengthen the recommendation not to change anti-PD-1/PD-L1 treatment plans based on current or future immunization schedules, implying that all these patients should be closely monitored.

Inactivated SARS-CoV-2 vaccination does not disturb the clinical course of Graves' disease: An observational cohort study

SARS-CoV-2 vaccination has been reported to be associated with the induction of thyroid disorders. To investigate the influence of SARS-CoV-2 vaccination on the disease course of patients who were undergoing treatment for Graves' disease (GD), a total of 651 consecutive GD patients who attended follow-up visits in Jiangyuan Hospital were enrolled in this retrospective study, including 443 inactivated SARS-CoV-2 vaccine recipients and 208 unvaccinated participants. The changes in serum levels of free triiodothyronine (fT3), free thyroxine (fT4), thyroid stimulating hormone (TSH) and TSH receptor antibody (TRAb) were analyzed. Crude and adjusted hazard ratios (HRs) were estimated using Cox regression models to investigate the risks in incident TRAb positivity and hyperthyroidism recurrence following vaccination. The median levels of TRAb and fT3 significantly decreased in both vaccinated and unvaccinated groups during the GD hyperthyroidism treatment. The fT4 levels of both groups were well within normal limits and presented downward trends simultaneously. Although the present study observed an increasing trend of TSH level during follow-up, significant difference was not seen in both vaccinated and unvaccinated groups. Except for newly diagnosed GD patients, vaccinated participants had significantly lower risks of incident TRAb positivity (adjusted HR = 0.22; 95%CI: 0.10-0.48, P < 0.001) after adjusted for sex, age, disease duration and MMI dose at baseline. Besides, vaccination was unlikely to serve as a risk factor for hyperthyroidism recurrence (adjusted HR = 1.20; 95%CI: 0.51-2.83, P = 0.678). Notably, newly diagnosed patients who received vaccination were just as likely to achieve remission of thyrotoxicosis as those not receiving the vaccination at any time. Our results concluded that inactivated SARS-CoV-2 vaccination would not disturb the treatment course among GD hyperthyroidism patients.

Incidence of diabetes following COVID-19 vaccination and SARS-CoV-2 infection in Hong Kong: A population-based cohort study

BACKGROUND

The risk of incident diabetes following Coronavirus Disease 2019 (COVID-19) vaccination remains to be elucidated. Also, it is unclear whether the risk of incident diabetes after Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection is modified by vaccination status or differs by SARS-CoV-2 variants. We evaluated the incidence of diabetes following mRNA (BNT162b2), inactivated (CoronaVac) COVID-19 vaccines, and after SARS-CoV-2 infection.

METHODS AND FINDINGS

In this population-based cohort study, individuals without known diabetes were identified from an electronic health database in Hong Kong. The first cohort included people who received ≥1 dose of COVID-19 vaccine and those who did not receive any COVID-19 vaccines up to September 2021. The second cohort consisted of confirmed COVID-19 patients and people who were never infected up to March 2022. Both cohorts were followed until August 15, 2022. A total of 325,715 COVID-19 vaccine recipients (CoronaVac: 167,337; BNT162b2: 158,378) and 145,199 COVID-19 patients were 1:1 matched to their respective controls using propensity score for various baseline characteristics. We also adjusted for previous SARS-CoV-2 infection when estimating the conditional probability of receiving vaccinations, and vaccination status when estimating the conditional probability of contracting SARS-CoV-2 infection. Hazard ratios (HRs) and 95% confidence intervals (CIs) for incident diabetes were estimated using Cox regression models. In the first cohort, we identified 5,760 and 4,411 diabetes cases after receiving CoronaVac and BNT162b2 vaccines, respectively. Upon a median follow-up of 384 to 386 days, there was no evidence of increased risks of incident diabetes following CoronaVac or BNT162b2 vaccination (CoronaVac: 9.08 versus 9.10 per 100,000 person-days, HR = 0.998 [95% CI 0.962 to 1.035]; BNT162b2: 7.41 versus 8.58, HR = 0.862 [0.828 to 0.897]), regardless of diabetes type. In the second cohort, we observed 2,109 cases of diabetes following SARS-CoV-2 infection. Upon a median follow-up of 164 days, SARS-CoV-2 infection was associated with significantly higher risk of incident diabetes (9.04 versus 7.38, HR = 1.225 [1.150 to 1.305])-mainly type 2 diabetes-regardless of predominant circulating variants, albeit lower with Omicron variants (p for interaction = 0.009). The number needed to harm at 6 months was 406 for 1 additional diabetes case. Subgroup analysis revealed no evidence of increased risk of incident diabetes among fully vaccinated COVID-19 survivors. Main limitations of our study included possible misclassification bias as type 1 diabetes was identified through diagnostic coding and possible residual confounders due to its observational nature.

CONCLUSIONS

There was no evidence of increased risks of incident diabetes following COVID-19 vaccination. The risk of incident diabetes increased following SARS-CoV-2 infection, mainly type 2 diabetes. The excess risk was lower, but still statistically significant, for Omicron variants. Fully vaccinated individuals might be protected from risks of incident diabetes following SARS-CoV-2 infection.

Effect of Inactivated and mRNA COVID-19 Vaccination on Thyroid Function Among Patients Treated for Hyperthyroidism

CONTEXT

Reports of thyroid dysfunction following COVID-19 vaccination included cases of relapse of Graves' disease and worsening of pre-existing Graves' disease. Little is known about the thyroid-specific outcomes among patients treated for hyperthyroidism who have received COVID-19 vaccination.

OBJECTIVE

Among patients treated for hyperthyroidism, we evaluated factors associated with not receiving the COVID-19 vaccination and whether COVID-19 vaccination was associated with thyroid function instability.

METHODS

We included consecutive patients treated for hyperthyroidism attending the thyroid clinic at a teaching hospital between January and September 2021. They were categorized into vaccinated and unvaccinated groups. The index date was the date of first-dose vaccination for the vaccinated group, and the first date of attendance in the inclusion period for the unvaccinated group. They were followed up until March 2022 or occurrence of thyroid function instability (worsening of thyroid function/increase in antithyroid drug dosage), whichever was earlier.

RESULTS

A total of 910 patients were included (mean age 51.6 years; 82.1% female). Of these, 86.2% had Graves disease and 67.3% were vaccinated (67.3% BNT162b2; 30.6% CoronaVac; 2.1% heterologous). Abnormal thyroid function and cardiovascular comorbidities were independently associated with unvaccinated status. Upon median follow-up of 5.3 months, thyroid function instability occurred in 15.9% of patients. COVID-19 vaccination did not increase risks of thyroid function instability (hazard ratio 0.78, 95% CI 0.56-1.09, P = .151); this was consistent in Graves disease, both types of vaccines, and regardless of whether baseline thyroid function was normal. Twenty-seven patients overtly thyrotoxic at the time of vaccination received COVID-19 vaccines without triggering a thyroid storm or difficulty in subsequent thyroid function control.

CONCLUSION

Among patients treated for hyperthyroidism, abnormal thyroid function was a factor predicting unvaccinated status. Our results should encourage patients treated for hyperthyroidism to receive COVID-19 vaccination to protect themselves from adverse outcomes and potential long-term sequelae of COVID-19.

A prospective follow-up on thyroid function, thyroid autoimmunity and long COVID among 250 COVID-19 survivors

PURPOSE

We evaluated the evolution of thyroid function and autoimmunity among COVID-19 survivors over 6 months in relation to interferon beta-1b treatment and long COVID.

METHODS

We included COVID-19 survivors managed in a major COVID-19 centre between July 2020 and May 2021 who were reassessed three and/or six months after acute COVID-19. Thyroid function tests (TFTs) and anti-thyroid antibody titres were measured at acute COVID-19, 3-month and 6-month.

RESULTS

250 COVID-19 survivors were included (mean age 52.7 years, 50.4% men). Persistent thyroid function abnormalities were more likely in those with abnormal TFTs in acute COVID-19 (P < 0.001). Among 51 patients with abnormal TFTs in acute COVID-19, 82.4% resolved upon follow-up. Of 199 patients with normal TFTs in acute COVID-19, only 4.5% had incident abnormal TFTs, more likely in interferon-treated patients (P = 0.044) and none clinically overt. Among 129 patients with complete 6-month follow-up for anti-thyroid antibody titres, there was no significant change overall, except for modest increase in anti-thyroid antibody titres among the 84 interferon-treated patients (P < 0.05 at both 3 months and 6 months). Long COVID occurred in 19.5% and 10.4% at 3 and 6 months respectively, where TFTs and anti-thyroid antibody titres were not predictive of its occurrence.

CONCLUSION

Over 6 months, most abnormal TFTs in acute COVID-19 resolved, with no significant incident thyroid dysfunction. SARS-CoV-2 infection did not lead to change in thyroid autoimmunity, while interferon treatment was associated with modest increase in anti-thyroid antibody titres. Thyroid function and anti-thyroid antibodies did not play a significant role in long COVID.

Population-Based Clinical Studies Using Routinely Collected Data in Hong Kong, China: A Systematic Review of Trends and Established Local Practices

Background: Routinely collected health data are increasingly used in clinical research. No study has systematically reviewed the temporal trends in the number of publications and analyzed different aspects of local research practices and their variations in Hong Kong, China, with a specific focus on research ethics governance and approval.

Methods: PubMed was systematically searched from its inception to March 28, 2023, for studies using routinely collected healthcare data from Hong Kong.

Results: A total of 454 studies were included. Between 2000 and 2009, 32 studies were identified. The number of publications increased from 5 to 120 between 2010 and 2022. Of the investigator-led studies using the Hospital Authority (HA)’s cross-cluster data (n = 393), 327 (83.2%) reported receiving ethics approval from a single cluster/university-based REC, whereas 50 studies (12.7%) did not report approval from a REC. For use of the HA Data Collaboration Lab, approval by a single hospital-based or University-based REC is accepted. Repeated submission of identical ethics applications to different RECs is estimated to cost HK$4.2 million yearly.

Conclusions: Most studies reported gaining approval from a single cluster REC before retrieval of cross-cluster HA data. Substantial cost savings would result if repeated review of identical ethics applications were not required.