Maternal Immunization During the Second Trimester with BNT162b2 mRNA Vaccine Induces a Robust IgA Response in Human Milk: A Prospective Cohort Study

BACKGROUND

The human milk antibody response following maternal immunization with the BNT162b2 mRNA vaccine is important for the protection of the infant during infancy. The vaccine-specific antibody response is still unclear at different stages of human milk production, as are the effects of maternal immunization timing on the robustness of the antibody response.

OBJECTIVES

The study aimed to assess the antibody response (IgG/IgA/IgM) during various lactation stages and identify the best vaccination timing during pregnancy.

METHODS

A prospective cohort study of 73 postpartum women who were administered the BNT162b2 COVID-19 mRNA vaccine during the second or third trimester of pregnancy were recruited. Statistical comparison was conducted using 16 human milk samples from a prepandemic control group.

RESULTS

Excluding 11 women, the study included 62 lactating women who were administered the mRNA vaccine during the second or third trimester of pregnancy. A total of 149 samples of human milk were collected at different lactation stages. Our findings reveal that colostrum exhibits significantly higher levels of IgG (95% confidence interval [CI]: 1.3, 9.0; P = 0.023), IgA (95% CI: 55.98, 100.2; P = 0.0034), and IgM (95% CI: 0.03, 0.62; P < 0.0001) compared with mature milk IgG (95% CI: 0.25, 0.43), IgA (95% CI: 9.65, 13.74), IgM (95% CI: 0.03, 0.04). The timing of maternal immunization affected the antibody response. The level of IgA in mature milk was higher when immunization occurred in the second trimester (95% CI: 11.14, 19.66; P = 0.006) than in the third trimester (95% CI: 7.16, 11.49). Conversely, IgG levels in mature milk were higher when immunization occurred during the third trimester (95% CI: 0.36, 0.65; P < 0.0001) than in the second trimester (95% CI: 0.09, 0.38).

CONCLUSIONS

Our study provides evidence that administering the mRNA vaccine to pregnant women during the second trimester increases vaccine-specific IgA levels during lactation. Considering the significance of human milk IgA in mucosal tissues and its prevalence throughout lactation, it is reasonable to recommend maternal immunization with the BNT162b2 mRNA vaccine during the second trimester. This trial was registered at the Helsinki Committee of the Tel Aviv Medical Center as clinical trial number 0172-TLV.

The Importance of Mid-Follicular Phase Luteinizing Hormone Rise in GnRH Antagonist-Based Ovarian Stimulation for IVF

INTRODUCTION

Previous publications examined the endocrinology of follicular stimulation, focusing on luteinizing hormone (LH) levels changes. In selected, good prognosis IVF patients, a sharp drop in LH serum level was demonstrated between cycle days 2 and 6.

OBJECTIVE

The purpose of this study was to examine if this finding holds true for unselected patients.

METHODS

We retrospectively included 165 consecutive patients treated with a GnRH antagonist-based ovarian stimulation protocol during the year 2015.

RESULTS AND CONCLUSIONS

In 33% of the patients an increase in LH, rather than the expected decrease, was demonstrated after 5 stimulation days. There was no difference in pregnancy outcome. Our results suggest that an increase in LH levels during ovarian stimulation occurs mainly in "high responders", or "low responders". LH rise in mid follicular phase may result in a sharp LH drop once a GnRH antagonist is given, and the possible need for LH supplementation.

Day two post retrieval 1500 IUI hCG bolus, progesterone-free luteal support post GnRH agonist trigger - a proof of concept study

Small dose of hCG (1500 IU) on the day of oocyte retrieval, followed by daily progesterone administration, is currently the preferred way to secure adequate luteal support following GnRH agonist trigger. In the current proof-of-concept study, we explored the possibility that a bolus of 1500 IU hCG, given two days after oocyte retrieval, may be sufficient to sustain adequate luteal support without additional progesterone treatment. From February 2015 to August 2016, we obtained 44 pregnancies following GnRHa trigger followed by day 2 hCG (1500 IU) support only (study group). Data from these 44 cycles were compared with the latest 44 pregnancies obtained following hCG (6500 IU) trigger followed by conventional progesterone luteal documented (control group). Mean progesterone levels (14 days postoocyte retrieval) in the study and control groups were 197 nmol/l and 173 nmol/l, respectively (NS). Mean E₂ levels (14 days post oocyte retrieval) in the study group was 6937 pmol/l, significantly higher (p < .001) than in the control group (3.276 pmol/l). We conclude that bolus of 1500 IU hCG, administered 2 days after retrieval, can provide excellent support, without the need to further supplement with progesterone.