Endocrine system after 2 years of COVID-19 vaccines: A narrative review of the literature

Purpose The purpose of this study was to describe the current knowledge on the potential endocrine adverse effects post-COVID-19 vaccines. Methods A PubMed/MEDLINE, Web of Science, and Scopus research was performed. Case reports, case series, original studies, and reviews written in English and published online up to 31 July 2022 were selected and reviewed. The final reference list was defined based on the relevance of each paper to the scope of this review. Results The available data showed that endocrine side effects are generally rare and with favorable outcome, being thyroid disorders the most common. Conversely, data on type 1 diabetes mellitus are rare; adrenal and pituitary events are even anecdotal. Finally, the available clinical studies suggest no impact on female reproductive system and on male and couple fertility. Conclusion Overall, these data show that, after 2 years of COVID-19 vaccines, the endocrine system is not heavily threatened.

To assess the association between SAT and COVID-19 vaccines, calculating the reporting odds ratios Median time to onset of SAT (after any vaccine): 10 days SAT was relatively more frequently reported in association with mRNA COVID-19 vaccines than with other viral vaccines.
Underreporting, overreporting and reporting bias; multiple confounding factors (comorbidity); the absence of critical data hinders a proper causality assessment for some of the cases

Bostan et al, 2022 (21)
Retrospecti ve study 55 patients diagnosed with SATm, of whom 16 had undergone vaccination against  Pfizer/BioNtecB NT162b2 (6), Sinovac Biotech CoronaVac in 6 (10) To identify cases of vaccine-associated SAT, analyse the characteristics of these cases, and compare them with cases of nonvaccine associated SAT diagnosed in the same period Median time to onset of symptoms after vaccination was 6.5 days No differences between vaccinated and unvaccinated SAT patients in terms of age, gender, time to diagnosis, thyroid volumes, thyroid function tests, and acute phase reactants. No differences concerning treatment (methylprednisolone), follow-up duration and the frequency of euthyroidism at the follow-up visit Retrospective design; limited sample size; lack of long-term follow-up To examine the effect of the SARS-CoV-2 virus vaccine on sperm quality All sperm donors donated sperm repeatedly before and 72 (or more) days after receiving the SARS-CoV-2 vaccine (two doses).
No deleterious effect on sperm quality for both fresh and frozen, thawed samples. Sperm quality improved after two doses of vaccine, as compared to sperm samples given in the months prior to vaccination. Sperm samples that were obtained after the first vaccine dose also did not show any negative effect on sperm quality, which was found to be improved compared to samples before vaccination.
The number of sperm samples available for analysis differed between subjects, according to the number of samples given during each period (before or after vaccination).

Safrai et al, 2022 (94)
Retrospecti ve study 72 M, median age 35.7 years, undergoing in vitro Pfizer/BioNtech BNT 16b2 To assess the effect of vaccine on sperm parameters of men with normal or Records of the same patients were reviewed before and after vaccine.

Median time between
Sperm parameters showed no significant changes after vaccination among men with a normal and abnormal semen analysis. Except sperm volume, Retrospective data collection of the sperm parameters of the prevaccine group; relatively long interval between the pre-and post-vaccination semen analyses. fertilization treatment.
impaired sperm parameters.
the first vaccine and the post-vaccine sperm analysis was 71 days.
which had a slightly decrease, none of the parameters differed after vaccination.

Lifshitz et al, 2022 (95)
Prospective cohort study 75 M, fertile (with a child without the use of artificial reproductive technology) and younger than 45 years Pfizer/BioNtech BNT 16b2 To assess the percentage of abnormal semen parameters in men who were vaccinated Semen samples were analysed 1-2 months following the second dose of vaccine The semen parameters following COVID-19 vaccination were predominantly within the normal reference ranges.
Men were only tested once after they were vaccinated and not before vaccination.

Olana et al, 2022 (96)
Singlecenter prospective study 47 M (age: 29.3 ± 6.0 years, BMI: 23.15 ± 2.5 kg/m2) To compare spermatozoa parameters before and after vaccine inoculation (two doses, one month apart) Semen samples were analysed before the first dose, and three months after the first dose No significant differences were observed in semen parameters in T0, compared to T1 for volume, concentration, total number, total and progressive motility, abnormal forms (confirmed also in sub analysis group including only oligo and asthenozoospermic patients) Men were selected from a specific population; small number of oligozoospermic individuals