The effect of COVID-19 vaccination during IVF stimulation on cycle outcomes- a retrospective cohort study.

The effect of the mRNA-BNT162b2 vaccine administered prior to fertility treatments has been addressed in several studies, presenting reassuring results. Cycle outcomes of patients receiving the vaccine during the stimulation itself have not been previously described. This retrospective cohort study included patients who received mRNA-BNT162b2-vaccine during the stimulation of fresh IVF cycles, between January-September 2021, age matched to pre-stimulation vaccinated patients and to non-vaccinated patients. Demographics, cycle characteristics and cycle outcomes were compared between groups. A total of 132 in-treatment vaccinated patients (study group), 132 pre-treatment vaccinated and 132 non-vaccinated patients that underwent fresh IVF cycles were included. Mean time from vaccination to retrieval in the study group was 6.68 days (SD 3.74; range 0-12). Oocyte yield was similar between groups (9.35 versus10.22 and 10.05 respectively; p=0.491). A linear regression model demonstrated no effect of vaccination before or during the stimulation, on oocyte yield (p>0.999). Clinical pregnancy rates (30 % versus 30 % versus 28 %) and ongoing pregnancy rates (25 % for all groups) did not differ between groups. In a logistic regression model for clinical pregnancy rates, vaccine administration and timing of vaccination were not a significant factor. This is the first study reporting the outcome of the mRNA BNT162b2 vaccine administration during the IVF stimulation itself. The vaccine administration had no impact on fresh IVF treatment outcomes compared to pre-treatment vaccinated or non-vaccinated patients. This adds to the growing evidence of COVID-19 vaccine safety in relation to fertility treatments and enables more flexibility regarding timing of vaccine administration.