P-518 The effect of inactivated SARS-CoV-2 vaccination on the outcome of the first frozen-thawed embryo transfer cycle
Authors: Liang K , Zhou L 
Published: June 2023

Abstract

Study question
Is there an effect of inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination on the outcome of the first frozen-thawed embryo transfer(FET) cycle.

Summary answer
Inactivated SARS-CoV-2 vaccination did not affect the outcome of the first FET cycle, including clinical pregnancy rate, early miscarriage rate and newborns’ birth weight.

What is known already
SARS-CoV-2 vaccination can significantly reduce the risk of severe disease and death after SARS-CoV-2 infection. However, due to the lack of vaccine safety data, the infertile population who plan to undergo ART treatment have high concerns about the safety of vaccine vaccination. To date, there are merely few researches aimed to determine the impact of inactivated SARS-CoV-2 vaccination on reproductive and neonatal outcomes of women attempting FET.

Study design, size, duration
This was a retrospective cohort study of patients who underwent the first FET cycle in the Reproductive Center of Ningbo Women and Children Hospital from November 1st 2021 to December 19th 2022. All patients were followed up until January 19th 2023. Patients whose age was &gt;40 years old were excluded. The patients were organized into groups based on age, anti-Müllerian hormone (AMH) levels, antral follicle count (AFC), body mass index (BMI), and vaccination or not.

Participants/materials, setting, methods
Patients fully vaccinated with two doses of Sinopharm or Sinovac inactivated vaccines(Group A, n = 452) were compared with unvaccinated patients(Group B, n = 452) who were matched by age, AMH, AFC and BMI. The baseline characteristics and clinical outcomes of each group were compared.SPSS version 26.0 (SPSS Inc., USA) was used for all data analyses.

Main results and the role of chance
There were no statistically significant differences in age, AMH, AFC, BMI, infertility duration, infertility type, infertility causes, fertilization type, ovarian stimulation protocol, number of oocytes retrieved(9.24 vs 9.92, p = 0.102), endometrial preparation protocol, endometrial thickness(9.40 vs 9.29mm, p = 0.344), embryo stage, number of embryos for transfer(1.4 vs 1.42, p = 0.589) between two groups. No difference was found between vaccinated and unvaccinated patients in clinical pregnancy rate(55.31% vs 57.52%, p = 0.502), early miscarriage rate(10.4% vs 11.54%, p = 0.681). The newborns’ birth weight were comparable between two groups(2971.44 vs 3156.83g, p = 0.66).

Limitations, reasons for caution
This is a single-center retrospective study and further accumulated data is warranted to validate the findings. Because of the short follow-up time, some patients are still pregnant, hence we await live birth outcomes.

Wider implications of the findings
These findings contribute to the evidence regarding the reproductive safety of inactivated SARS-CoV-2 vaccination for fertility-seeking women, and it can provide further theoretical reassurance for doctors and patients to vaccinate before pregnancy.

Trial registration number
not applicable