Study: mRNA Injection Reduces Ovarian Reserve in Rats

Simian Practicalist
Jul 8
2 min read

A study by E. Karaman et al titled “Impact of mRNA and Inactivated COVID-19 Vaccines on Ovarian Reserve” posted on 24 April 2025 has found that COVID-19 vaccines, particularly the mRNA version, reduce ovarian reserve in rats.

The paper is 16 pages with the main text at about 12 pages. The remaining are references.

The aim of the study is

…to investigate the effects of mRNA and inactivated COVID-19 vaccines on ovarian follicles and ovarian reserve by quantifying the expression of TGF-β1, VEGF, caspase-3, and AMH, as well as the stages of follicular development in rat ovarian tissue post-vaccination.

The study sample comprised 30 female Wistar albino rats, aged 16–24 weeks, weighing 240 ± 30g. These were divided into three groups of 10: Group I (control), Group II (mRNA vaccine using Pfizer-BioNTech) and Group III (inactivated vaccine using Sinovac).

Our findings revealed that follicular VEGF, TGF-β1, and caspase-3 expression, as well as the mean atretic follicle (ATF) count, were elevated in the vaccine groups compared to the control group, whereas serum anti-Müllerian hormone (AMH) levels decreased across all follicular forms, except for the mean ATF count. These results consistently indicate that both COVID-19 vaccines, particularly the mRNA vaccine, may exert toxic effects on ovarian follicles and ovarian reserve in rats.

More specifically regarding the elevated TGF-β1 expression in the ovarian tissues in vaccinated groups:

These findings suggest that COVID-19 vaccines, particularly mRNA vaccines, may enhance TGF-β1-mediated processes such as mitosis, angiogenesis, cell migration, and extracellular matrix remodeling in ovarian tissue, particularly within follicles composed of diverse cell types and structures. It is seen that vaccination triggers systemic inflammatory responses, leading to increased cytokine production, including IL-6, TNF-α, IL-1 β and TGF-β1, which play key roles in folliculogenesis, angiogenesis, and atresia. Our findings indicate elevated TGF-β1 expression, which has been associated with ovarian tissue remodeling and fibrosis.

Figure 2: Immunohistochemical staining of TGF-β1 in ovarian sections from the control (A), mRNA vaccine (B), and inactivated vaccine (C) groups. Arrows: immunopositive cells. Scale bars: 100 μm

In short, the findings

…demonstrate that both vaccines, particularly the mRNA vaccine, are associated with a reduction in ovarian reserve, characterized by depletion of the primordial follicle pool and increased follicular loss via apoptosis throughout folliculogenesis.