The emergence and rapid outbreak of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) resulted within the coronavirus disease 2019 (COVID-19) pandemic. Throughout the COVID-19 pandemic, scientists have worked rapidly to develop quite a few vaccines, several of which received emergency use authorization from global regulatory bodies, resembling america Food and Drug Administration (FDA).

Study: Longitudinal antibody response kinetics following SARS-CoV-2 messenger RNA vaccination in pregnant and nonpregnant individuals. Image Credit: Marina Demidiuk / Shutterstock.com

Background

Generally, pregnancy triggers an immunogenic shift to a Th2-mediated immunity, which could also result in a differential response to infection on this patient population. SARS-CoV-2 infection has been related to antagonistic pregnancy outcomes, including maternal death, preterm delivery, stillbirth, mechanical ventilation, and maternal intensive care unit (ICU) admission. 

Although COVID-19 vaccination has been really useful for pregnant women, there stays a scarcity of information available regarding its efficacy on this group. That is primarily attributable to the exclusion of pregnant women from initial COVID-19 messenger RNA (mRNA) vaccine trials. 

Nevertheless, a sturdy maternal immune response has been reported after vaccination with mRNA-lipid nanoparticle (LNP) COVID-19 vaccines. As well as, in comparison with nonpregnant individuals, pregnant women exhibited a differential response to some vaccinations across gestational ages.

Subsequently, it’s imperative to grasp whether the immunologic milieu of pregnancy affects the longitudinal vaccine response to mRNA-based immunization. Moreover, the long-term efficacy and kinetics of antibody responses induced after vaccination between pregnant and nonpregnant women ought to be further elucidated.

Concerning the study

A recent American Journal of Obstetrics Gynecology MFM study evaluated the longitudinal antibody response kinetics related to two doses of mRNA-LNP-based SARS-CoV-2 vaccines developed by Pfizer-BioNTech (BNT162b2) or Moderna (mRNA-1273) in pregnant women across different gestational ages. All participants received vaccines between December 18, 2020, and June 26, 2021.

The vaccine-induced antibody response in pregnant women was compared with that of nonpregnant individuals. To this end, blood samples were collected from participants at different time points, including the time of the primary (t0) and second vaccine doses (t1), two weeks after the second vaccine dose (t2), and serial longitudinal follow-up as much as 41.7 weeks after administration of the primary vaccination dose.

Enzyme-linked immunosorbent assay (ELISA) was conducted to find out the presence of anti-spike (S) immunoglobulin M (IgM), IgG, and IgA in participants’ blood samples. Participants with a history of SARS-CoV-2 infection, based on the presence of anti-nucleocapsid antibodies, were excluded from the present study. Pregnant women who received the booster vaccine dose and those that weren’t fully vaccinated with two-doses by the point of delivery were also excluded. 

Study findings

A complete of 53 pregnant women were included within the study. The nonpregnant cohort included data from 21 participants, whose median age was 36 years. Not one of the participants from this group reported immunosuppressed conditions nor were they taking immunosuppressing medication. 

All pregnant study participants delivered liveborn infants between April 13, 2021, and November 29, 2021. Umbilical cord blood samples were collected from 49 patients and were analyzed.

Not one of the participants were immunosuppressed nor were they under immunosuppressing medication. The median maternal age was 35 years and gestational ages during vaccine administration and delivery were 26.3 weeks and 39.6 weeks, respectively.

The anti-S IgA, IgG, and IgM responses at t1 and t2 weren’t significantly related to the gestational age at immunization. Thus, the anti-S responses in pregnant participants were independent of gestational age.

A comparison of various immune responses between pregnant and nonpregnant participants revealed that IgM levels were significantly higher within the nonpregnant cohort at t2. Moreover, an elevated IgA response was also noted within the nonpregnant cohort at t1 and t2. No significant difference in IgG responses was observed within the cohorts.  

Notably, the very best level of antibody responses occurred two weeks after the second vaccine dose for each cohorts. A decline in anti-S IgG, IgM, and IgA levels was observed over time, with an identical pattern reported in each pregnant and nonpregnant individuals. Maternal anti-S IgG levels were just like umbilical cord anti-S IgG levels. 

Conclusions

The present study demonstrates that the immunologic milieu of pregnancy has no effect on the sturdiness of the anti-S IgG response to COVID-19 vaccination. At present, scientists are studying the clinical implications of low levels of vaccine-induced IgA and IgM response in pregnant individuals and whether this difference in immune response affects pregnant women.

The authors strongly recommend COVID-19 vaccination at any point while pregnant, because it should protect not only the mother but additionally the kid through robust passive antibody transfer.

Journal reference:

• Prabhu, M., Yang, Y. J., Johnston, C. D., et al. (2023) Longitudinal antibody response kinetics following SARS-CoV-2 messenger RNA vaccination in pregnant and nonpregnant individuals. American Journal of Obstetrics Gynecology MFM, 5(2). doi:10.1016/j.ajogmf.2022.100796