Studies support primary SARS-CoV-2 vaccination and the use of booster immunity during pregnancy

In a recent study posted on medRxiv* Preprint server, researchers found that the immune response to primary vaccination and booster immunization of coronavirus disease 2019 (COVID-19) during pregnancy, and maternal booster immunity to transplacental antibody transfer to infants in the United States. The effect of administration was evaluated.

Pregnant women are at increased risk of COVID-19 severity, and infants infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) <6 months are at increased risk of hospitalization. Therefore, SARS-CoV-2 vaccination is essential during pregnancy for the alleviation of COVID-19. Since October 2021, pregnant women have been eligible for the COVID-19 vaccine booster, but data on booster-induced immune responses during pregnancy are still limited.

About research

In this study, researchers measured the immune response evoked by COVID-19 primary and booster messenger ribonucleic acid (mRNA) vaccination during pregnancy and the introduction of transplacental antibodies into infants in the United States.

The study consisted of pregnant women enrolled from nine academic sites between July 6, 2021 and January 31, 2022, and was followed up to one year after delivery. Study participants received two primary vaccinations with the mRNA-1273 vaccine or the Pfizer-BioNTech vaccine and / or booster vaccination with the COVID-19 mRNA vaccine during pregnancy and childbirth.

Serum samples were taken before and after COVID-19 mRNA vaccination (from 2 weeks after vaccination to the birth of the newborn). Maternal and cord blood samples were taken during labor. Binding antibody or immunoglobulin G (IgG) titers to the SARS-CoV-2 spike (S) protein and S receptor binding domain (RBD) were evaluated and shown in bound antibody units (BAU) / mL.

The Neutralizing antibody (NAb) Titer was determined using live virus defocusing neutralization titer (FRNT) Assay using virus carrying variant S of SARS-CoV-2 Delta, D614G, and Omicron BA.1 strain. The nAb titer was expressed as the serum inhibitory diluent required to neutralize the SARS-CoV-2 strain by 50% (ID).₅₀). Transplacental transfer of antibodies was assessed based on the ratio of antibody titers in serum obtained from maternal and umbilical cord blood during labor.

The study exposure was primary or booster immunization COVID-19 mRNA vaccination during pregnancy, and the main results were SARS-CoV-2 binding IgG titers and nAb after primary or booster vaccination during pregnancy and antibody introduction into infants. It was the generation of titers. Immune responses were compared between primary and booster vaccinated individuals in maternal serum and cord blood at birth.

result

A total of 240 mothers were included in the analysis, of which 100 women and 67 women received two doses of the Pfizer-BioNTech vaccine (102 babies) and the mRNA-1273 vaccine (68 babies), respectively. I received a primary vaccination regimen. Booster vaccination was given to 73 women (75 babies), most of whom (81%) were of the same type of vaccine booster.

Serologically bound S and SRBD IgG titers were observed in all primary and boost immunovaccinated individuals and all cord blood samples during follow-up evaluation (post-vaccination and at birth). Substantially higher titers were detected during follow-up among booster vaccinated individuals than at primary mRNA vaccinated individuals. At delivery, booster vaccinated individuals have an S IgG geometric mean titer (GMT) of 2,201 BAU / mL, 9 times higher than Pfizer-BioNTech primary vaccinated individuals (236 BAU / mL) and mRNA-1273 vaccinated individuals. It was 4.6 times higher. (479 BAU / mL), respectively.

In addition, booster doses elicit substantially higher S IgG titers (GMT 3,290 BAU / mL) between cord blood samples, which is 9-fold higher than primary Pfizer-BioNTech vaccinated (GMT 369 BAU / mL). It was high, 4.2 times higher. Primary mRNA-1273 vaccinated (GMT 792 BAU / mL). During the follow-up visit, the same trend was observed for SRBD-binding antibody titers in cord blood.

Binding antibody titers to S and SRBD are higher than the total dose of the primary vaccine (m-1273 and Pfizer–BioNTech vaccinated) among booster vaccinated, adjusted for data on the time elapsed since the last vaccination. It was 0.6 log 10 higher at the time of delivery. Booster vaccinated person (ID)₅₀ 630) Primary vaccinated person (ID)₅₀ 62 and 193–BioNTech and mRNA-1273 vaccinated for Pfizer).

nAb titers are for all booster immunovaccinated individuals (ID)₅₀ 446) Compared to 68% of primary Pfizer–BioNTech vaccinated (ID)₅₀ 50) and 96% of primary pre-mRNA-1273 vaccinated (ID)₅₀ 180). Omicron nAb titers were detected in only 9% of Pfizer vaccinated individuals at birth (ID)₅₀ 13) and 22% of pre-mRNA-1273 vaccinated (ID)₅₀ 15). On the contrary, 73% of booster vaccinated (ID)₅₀ 60) The nAb titer of Omicron BA.1 was shown. Delta neutralization was higher than D614G neutralization, but lower than Omicron BA.1 neutralization.

Similarly, in cord blood, the nAb titer of D614G was substantially higher among booster vaccinated (ID).₅₀ 743) Than Primary Pfizer–BioNTech Vaccine (ID)₅₀ 77) and the mRNA-1273 vaccinated person (ID)₅₀ 135). Notably, the nAb titer of Omicron was substantially higher in cord blood samples obtained from booster immunovaccinated individuals (reaction rate 88%, ID).₅₀ 109) Primary Pfizer-More than obtained from BioNTech vaccinated (14% response rate, ID)₅₀ 13) or mRNA-1273 vaccinated (response rate 22%, ID)₅₀ 15). Transplacental antibody transfer was efficient after primary and booster vaccination, with mean transplacental transfer ratios ranging from 1.6 to 1.8 for bound antibodies and 1.0 to 1.8 for nAb. ..

In conclusion, based on the study results, primary and boosted immunity COVID-19 mRNA vaccination should continue to be given to pregnant women.

*Important Notices

medRxiv publishes unpeer-reviewed preliminary scientific reports and should not be considered definitive, guide clinical / health-related behaviors, or be treated as established information.