SARS-CoV-2 infection leads to higher IgA levels in breast milk than vaccination

Compared to infant formula, breast milk contains antibodies that provide the infant with passive immunity against many infectious diseases.Recent papers in journals eye science Exploring the existence and effectiveness of Neutralizing antibody Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in breast milk after infection, vaccination with different vaccines, or both.

study: Assessment of SARS-CoV-2 neutralizing antibody titers in breast milk from convalescent and vaccinated mothers. Image credit: BaLL LunLa/Shutterstock.com

prologue

During the 2019 coronavirus disease (COVID-19) pandemic, many pregnant women were infected with SARS-CoV-2 or were vaccinated. Unfortunately, some vaccinated women have experienced breakthrough infections (BTIs) and reinfections, while others have been vaccinated after recovering from COVID-19. These women are believed to have hybrid immunity.

About research

The current study utilized 84 breast milk samples from 84 women. Eight of them had a history of her COVID-29 during her first three months after the pandemic was declared in March 2020. 2022.

Breast milk donors had received the messenger ribonucleic acid (mRNA) vaccine Comirnaty or mRNA-1273 or the adenoviral vector vaccine ChAdOx1, had a history of, or were infected with COVID-19 and were vaccinated . There were 16 of her participants in each vaccine group, all of whom had received two of her vaccinations.

Another 10 samples were from mothers who received the third Comirnaty booster vaccination. Her five samples were obtained from a mother who was vaccinated after recovering from her COVID-19 between March 2020 and her December 2020. These samples were taken on her 7th day and her 15th day from her first administration of Comirnaty.

None of the ChAdOx1 recipients delivered by caesarean section. Second, mothers who were vaccinated after recovering from her COVID during the Omicron wave were vaccinated significantly longer after the birth of their babies compared to mothers infected during the first wave. tended to.

with pseudovirus Consists of vesicular stomatitis virus (VSV) expressing SARS-CoV-2 spike protein From the Ancestral, Delta, or Omicron BA.1 strains, the researchers tested all milk samples for their neutralizing ability.

mother’s breast milk in convalescence

The highest neutralization titers were found in breast milk samples from convalescent mothers. Neutralizing capacity was positively correlated with the titer of immunoglobulin (Ig) A, a mucosal antibody, but not with IgG.

Poor BA.1 neutralization was observed in all samples from convalescent mothers compared with the ancestral variant in 85% and 100%, respectively. About half of the samples also neutralized the Delta variant.

When stratified by duration of infection, none of the samples infected during the first wave were able to neutralize BA.1. Less than 40% of Omicron-infected samples were able to neutralize BA.1. However, 11 out of 13 samples neutralized the ancestral strain. These findings reflect the ability of BA.1 to escape neutralization.

Most neutralizing antibodies targeted the SARS-CoV-2 spike receptor binding domain (RBD). Both Omicron and his ancestral SARS-CoV-2 infection generated comparable titers of IgA antibodies against RBD. By comparison, IgG anti-RBD levels were higher in those infected during the Omicron wave. However, these mothers had received at least two of her vaccinations.

Neutralizing antibody titers showed poor correlation with IgG titers. However, this was not the case for anti-RBD IgA neutralizing antibody titers, which were positively correlated. Neutralization may therefore be primarily due to IgA rather than his IgG antibodies.

Neutralizing antibody titers were higher in samples from convalescent mothers of either wave compared to vaccinated mothers.

breast milk of vaccinated mothers

Both mRNA vaccines induce neutralizing antibodies to the ancestral virus with similar titers in approximately half of vaccinated mothers. However, milk samples obtained from individuals receiving ChAdOx1 did not contain neutralizing antibodies.

For Delta variants, the proportion of samples showing neutralization was 25% for the mRNA-1273 group and 6% for Comirnaty. In BA.1, neutralization occurred in his one sample of the mRNA-1273 group.

Anti-RBD IgA was positive in all samples from mRNA-vaccinated mothers, but only in a quarter of ChAdOx1 mothers. Similarly, ChAdOx1 maternal milk antibody titers were low. For anti-RBD IgG, all three groups had similar positivity rates between 93% and 100%. However, ChAdOx1 had significantly lower titers.

Among vaccinated mothers, both anti-RBD IgG and IgA showed correlations with neutralizing antibody titers, although the latter was associated with a stronger association. IgA antibody titers also increased with lactation.

IgA is likely associated with neutralization of SARS-CoV-2 in breast milk”

Booster doses did not appear to cause changes in IgA or IgG titers in breast milk. Neutralization capacity against ancestral and delta strains was significantly higher in samples from infected and then vaccinated females. However, BA.1 continued to evade neutralization.

Neutralizing antibodies to the ancestral variant were higher in this group compared with groups receiving 2 or 3 doses of vaccine. Neutralizing antibody titers correlated with both anti-RBD IgA and IgG, and total IgA, which increased with duration of breastfeeding.

What is the impact?

Vaccination mainly induces IgG antibodies compared to IgA. IgA is produced more after natural infection. The superior immune response observed after infection compared to vaccination supports the higher neutralizing responses generated during infection. Notably, BA.1 was capable of immune escape after infection and vaccination.

Neutralizing antibody titers correlated with anti-RBD IgA titers in samples from convalescent women. This observation highlights the important protective role of IgA.

IgA is the most abundant isotype in breast milk as it constitutes 70% to 90% of all antibodies. In breast milk, this antibody exists as a dimeric secretory IgA (sIgA) that covers mucosal surfaces and has high antiviral activity.

This finding suggests a protective value of sIgA in breast milk against the respiratory pathogen SARS-CoV-2. In addition, anti-SARS-CoV-2 IgA persists longer than IgG.

ChAdOx1 failed to produce neutralizing antibodies in breast milk. This confirms previous studies reporting lower or lower levels of IgA and other antibodies with vector-based vaccines compared to highly neutralizing antibody responses after mRNA vaccination.

Breast milk provides a constant stream of antibodies to infants and may prevent or reduce the severity of COVID-19 in infants. Further research may help identify ways to improve neutralizing antibody titers in breast milk to enhance infant protection.

Overall, our results suggest that breast milk from naturally infected women or those vaccinated with an mRNA-based vaccine contains a SARS-CoV-2 neutralizing agent that may protect breastfed infants from infection. shows that it contains antibodies”