Association of Human Milk Antibody Induction, Persistence, and Neutralizing Capacity With SARS-CoV-2 Infection vs mRNA Vaccination

Point-of-care human milk concentration by passive osmosis: comprehensive analysis of fresh human milk samples

OBJECTIVE

Preterm infants need enrichment of human milk (HM) for optimal growth. This study evaluated a novel, point-of-care human milk concentration (HMC) process for water removal from fresh HM samples by passive osmotic concentration.

STUDY DESIGN

Nineteen fresh HM samples were concentrated by incubation with the HMC devices for 3 h at 4 °C. Pre- and post-concentration HM samples were compared by HM properties for: pH, osmolality, macronutrients, enzyme activity, bioactive, and total cell viability.

RESULTS

Passive osmotic concentration reduced HM volume by an average of 16.3% ± 3.8% without a significant effect on pH or cell viability. Ten of the 41 HM components did not differ significantly (p > 0.05) between pre- and post-concentration samples. Twenty-three increased within the expected range by volume reduction. Six increased more than expected, two less than expected, and none decreased significantly.

CONCLUSION

Passive osmotic concentration of fresh HM can concentrate HM components by selective removal of water. HM osmolality and pH remained within neonatal feeding parameters.

Differences in clinical characteristics of early-onset and late-onset severe acute respiratory syndrome coronavirus 2 infections in neonates

Differences in clinical characteristics of early-onset and late-onset severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections in neonates remain unclear. This study aimed to determine whether there are differences in the main clinical, radiological, and laboratory features of early-onset and late-onset SARS-CoV-2 infections in neonates. This single-center, prospective cohort study enrolled neonates with SARS-CoV-2 infection from December 7, 2022, to January 3, 2023, and evaluated their clinical characteristics during hospitalization. All neonates (N = 58) infected with SARS-CoV-2 within 28 days of birth who were admitted to the neonatal intensive care unit of Taizhou Hospital were included. These neonates were classified into the early-onset (diagnosed within 7 days of birth) and late-onset (diagnosed more than 7 days after birth) groups. The symptoms, treatment, and prognosis of SARS-CoV-2 infection were the main study outcomes. The incidence of hospitalization attributable to SARS-CoV-2 infection was 10.6% (58 of 546 neonates) in Linhai. Sixteen (28%) of the 58 SARS-CoV-2 infections were early-onset cases, and 42 (72%) were late-onset cases. The common symptoms among the late-onset group were fever (p < 0.001) and cough (p < 0.001). Neonates with late-onset SARS-CoV-2 infection (p < 0.001) were significantly more likely to develop pneumonia.  Conclusion: The clinical symptoms and rates of pneumonia caused by SARS-CoV-2 infection in neonates differed between the early-onset and late-onset groups. Different clinical management is necessary for neonates with early-onset and late-onset SARS-CoV-2 infections. What is Known: • Neonates are susceptible to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). • Differences in clinical characteristics of early-onset and late-onset SARS-CoV-2 infections in neonates remain unclear. What is New: • Fever and cough were the most common symptoms among neonates with late-onset infection. • Neonates with late-onset SARS-CoV-2 infection were more likely to develop pneumonia.

Prevalence and duration of SARS-CoV-2 fecal shedding in breastfeeding dyads following maternal COVID-19 diagnosis

Background

There is a paucity of data on the presence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in feces of lactating women with coronavirus disease 2019 (COVID-19) and their breastfed infants as well as associations between fecal shedding and symptomatology.

Objective

We examined whether and to what extent SARS-CoV-2 is detectable in the feces of lactating women and their breastfed infants following maternal COVID-19 diagnosis.

Methods

This was a longitudinal study carried out from April 2020 to December 2021 involving 57 breastfeeding maternal-infant dyads: 33 dyads were enrolled within 7 d of maternal COVID-19 diagnosis, and 24 healthy dyads served as controls. Maternal/infant fecal samples were collected by participants, and surveys were administered via telephone over an 8-wk period. Feces were analyzed for SARS-CoV-2 RNA.

Results

Signs/symptoms related to ears, eyes, nose, and throat (EENT); general fatigue/malaise; and cardiopulmonary signs/symptoms were commonly reported among mothers with COVID-19. In infants of mothers with COVID-19, EENT, immunologic, and cardiopulmonary signs/symptoms were most common, but prevalence did not differ from that of infants of control mothers. SARS-CoV-2 RNA was detected in feces of 7 (25%) women with COVID-19 and 10 (30%) of their infants. Duration of fecal shedding ranged from 1-4 wk for both mothers and infants. SARS-CoV-2 RNA was sparsely detected in feces of healthy dyads, with only one mother's and two infants' fecal samples testing positive. There was no relationship between frequencies of maternal and infant SARS-CoV-2 fecal shedding (P=0.36), although presence of maternal or infant fever was related to increased likelihood (7-9 times greater, P≤0.04) of fecal shedding in infants of mothers with COVID-19.

Association between maternal stress and premature milk cortisol, milk IgA, and infant health: a cohort study

Background

Maternal stress is pervasive in the neonatal intensive care unit (NICU). Maternal stress is associated with changes in human milk (HM) immunomodulatory agents, which may impact neonatal health. We sought to determine the association between maternal stress, HM immunoglobulin A (IgA) and cortisol, and to assess how these milk components correlate with infant immune and neurodevelopmental outcomes. We then compared how these associations persist over time.

Methods

The study design involved a cohort study of exclusively breastfeeding mothers and their singleton moderately preterm (28-34 weeks) infants admitted to the NICU. We collected maternal serum, maternal saliva, and first-morning whole milk samples, and administered maternal stress questionnaires at 1 and 5 weeks postpartum. We analyzed the samples for HM IgA (using a customized immunoassay in skim milk) and for HM and salivary cortisol (using a chemiluminescent immunoassay). Infant illness was assessed using the Score for Neonatal Acute Physiology II (SNAP II) and SNAP II with Perinatal Extension (SNAPPE II), and infant neurodevelopment were assessed using the Test of Infant Motor Performance. We analyzed changes in HM IgA and cortisol over time using paired t-tests. Furthermore, we performed correlation and regression analyses after adjusting for gestational age (GA), corrected GA, and infant days of life.

Results

In our study, we enrolled 26 dyads, with a mean maternal age of 28.1 years, consisting of 69% white, 19% Black, and 8% Hispanic. Cortisol: Salivary and HM cortisol were closely associated in week 1 but not in week 5. Though mean salivary cortisol remained stable over time [2.41 ng/mL (SD 2.43) to 2.32 (SD 1.77), p = 0.17], mean HM cortisol increased [1.96 ng/mL (SD 1.93) to 5.93 ng/mL (SD 3.83), p < 0.001]. Stress measures were inversely associated with HM cortisol at week 1 but not at week 5. IgA: HM IgA decreased over time (mean = -0.14 mg/mL, SD 0.53, p < 0.0001). High maternal stress, as measured by the Parental Stressor Scale: neonatal intensive care unit (PSS:NICU), was positively associated with HM IgA at week 5 (r = 0.79, P ≤ 0.001). Higher IgA was associated with a lower (better) SNAP II score at week 1 (r = -0.74, p = 0.05). No associations were found between maternal stress, salivary cortisol, HM cortisol, or HM IgA and neurodevelopment at discharge (as assessed using the TIMP score). Furthermore, these relationships did not differ by infant sex.

Conclusion

Maternal stress showed associations with HM cortisol and HM IgA. In turn, HM IgA was associated with lower measures of infant illness.

SARS-CoV-2 antibodies and their neutralizing capacity against live virus in human milk after COVID-19 infection and vaccination: prospective cohort studies

BACKGROUND

There is limited understanding of the impact of coronavirus disease 2019 (COVID-19) infection and vaccination type and interval on severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) human milk antibodies and their neutralizing capacity.

OBJECTIVES

These cohort studies aimed to determine the presence of antibodies and live virus neutralizing capacity in milk from females infected with COVID-19, unexposed milk bank donors, and vaccinated females and examine impacts of vaccine interval and type.

METHODS

Milk was collected from participants infected with COVID-19 during pregnancy or lactation (Cohort-1) and milk bank donors (Cohort-2) from March 2020-July 2021 at 3 sequential 4-wk intervals and COVID-19 vaccinated participants with varying dose intervals (Cohort-3) (January-October 2021). Cohort-1 and Cohort-3 were recruited from Sinai Health (patients) and through social media. Cohort-2 included Ontario Milk Bank donors. Milk was examined for SARS-CoV-2 antibodies and live virus neutralization.

RESULTS

Of females with COVID-19, 53% (Cohort-1, n = 55) had anti-SARS-CoV-2 IgA antibodies in ≥1 milk sample. IgA+ samples (40%) were more likely neutralizing than IgA- samples (odds ratio [OR]: 2.18; 95% confidence interval [CI]: 1.03, 4.60; P = 0.04); however, 25% of IgA- samples were neutralizing. Both IgA positivity and neutralization decreased ∼6 mo after symptom onset (0-100 compared with 201+ d: IgA OR: 14.30; 95% CI: 1.08, 189.89; P = 0.04; neutralizing OR: 4.30; 95% CI: 1.55, 11.89; P = 0.005). Among milk bank donors (Cohort-2, n = 373), 4.3% had IgA antibodies; 23% of IgA+ samples were neutralizing. Vaccination (Cohort-3, n = 60) with mRNA-1273 and shorter vaccine intervals (3 to <6 wk) resulted in higher IgA and IgG than BNT162b2 (P < 0.04) and longer intervals (6 to <16 wk) (P≤0.02), respectively. Neutralizing capacity increased postvaccination (P = 0.04) but was not associated with antibody positivity.

CONCLUSIONS

SARS-CoV-2 infection and vaccination (type and interval) impacted milk antibodies; however, antibody presence did not consistently predict live virus neutralization. Although human milk is unequivocally the best way to nourish infants, guidance on protection to infants following maternal infection/vaccination may require more nuanced messaging. This study was registered at clinicaltrials.gov as NCT04453969 and NCT04453982.

SARS-CoV-2 neutralizing antibody titers in maternal blood, umbilical cord blood, and breast milk

OBJECTIVE

We quantified neutralizing SARS-CoV-2 antibody against spike protein (nAb) levels after vaccination and SARS-CoV-2 infection in maternal serum, cord blood, and breast milk and determined whether they correlate with levels of spike protein binding antibody.

STUDY DESIGN

Women (n = 100) were enrolled on admission for delivery. Previous SARS-CoV-2 infection was defined by anti-nucleocapsid antibodies. Levels of nAb and binding antibodies against spike receptor binding domain were measured in maternal blood, cord blood, and milk.

RESULTS

Maternal nAb levels were higher after vaccine and infection than vaccine alone but waned rapidly. Levels of nAb in cord blood and milk correlated with maternal levels and were higher in cord blood than maternal. Spike protein binding antibody levels correlated with nAb.

CONCLUSION

SARS-CoV-2 vaccination near delivery may boost antibody-mediated immunity in the peripartum period. Neutralizing antibodies are passed transplacentally and into milk. Spike protein binding antibody may be a feasible proxy for nAb.

Exploring the long-term seroprevalence of SARS-CoV-2 antibodies in infants born to women with clinical or laboratory-confirmed COVID-19

INTRODUCTION

Infants are at a higher risk of severe illness with COVID-19 infection compared to older children. While COVID-19 vaccination is not recommended for young infants, they can acquire maternally-derived anti-SARS-CoV-2 antibodies passively through the placenta and breastmilk. We described the persistence of infection-induced maternal antibodies in infant circulation at 9-12 months of age.

METHODOLOGY

This was a cross-sectional study nested within the INTERCOVID multinational cohort study. For each COVID positive pregnant woman, two unmatched consecutive COVID negative pregnant women were enrolled between April and September 2020. Women with a positive PCR test, radiographic signs consistent with COVID-19, or at least 2 predefined symptoms of COVID-19 were considered as COVID positive. For this nested cross-sectional study, all COVID positive and either one of the COVID negative participants recruited from the Aga Khan University, Pakistan were approached 9-12 months after delivery, and maternal and infant sera were collected for antibody detection.

RESULTS

Altogether, 83 mothers provided consent, of whom 32 (38.6 %) were COVID positive and 51 (61.4 %) were COVID negative during pregnancy. Anti-SARS-CoV-2 antibodies were present in 13 (41 %) infants born to COVID positive and 19 (39 %) infants born to COVID negative mothers (p = 0.87). The presence of reactive antibodies in infants at follow-up was associated with maternal antibodies at follow-up (OR:9.50, 95 % CI:2.03-44.42; p = 0.004). COVID infection occurred in 3 (6 %) infants born to COVID negative mothers while no infant born to a COVID positive mother had a history of infection (p = 0.27).

CONCLUSION

The presence of reactive anti-SARS-CoV-2 antibodies in infants at 9-12 months of age is associated with maternal seropositivity 9-12 months after delivery rather than maternal infection during pregnancy. Further studies are required to validate these findings and assess whether passive immunity in infants is protective against COVID-19 infection.

Investigation of Anti-SARS-CoV-2-specific IgG Levels in Breast Milk after Vaccination or COVID-19 Infection

OBJECTIVE

 Newborns are vulnerable to all types of infections due to their developing immune system. To compensate for their immune immaturity, newborns rely on the passive transfer of antibodies through the placenta and own mother's breast milk (BM). In the present study, we investigated whether vaccination against SARS-CoV-2 leads to the presence of antibodies in BM. Furthermore, we compared the levels of SARS-CoV-2-specific anti-spike (anti-S) IgG antibodies in the BM of mothers who were vaccinated against Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or had coronavirus disease 2019 (COVID-19) infection naturally or were vaccinated after natural infection.

STUDY DESIGN

 This was a prospective cohort study conducted in the Ondokuz Mayis University Faculty of Medicine. Forty-six mothers who had at least two doses of the BNT162b2 messenger RNA-based vaccine and/or had a history of symptomatic COVID-19 infection were included in the study. BM samples were analyzed by the Abbott Architect SARS-CoV-2 IgG II Quant kit following the manufacturer's instructions.

RESULTS

 Forty-six mothers with an average age of 29.7 ± 5.7 years participated the study: 18 (39.1%) had COVID-19 infection + BTN162b2 vaccine, 17 (37.0%) had BTN162b2 vaccine, and 11 (23.9%) had natural infection. The highest SARS-CoV-2-specific anti-S IgG antibody titers in BM were found in mothers who were vaccinated following the infection (anti-SARS-CoV-2 IgG: 32.48 ± 57.1 arbitrary units AU/mL). However, no significant difference in anti-SARS-CoV-2 antibody levels was observed between the three groups (p = 0.641). No antibody was detected in 15.2% of BM samples.

CONCLUSION

 Both vaccination and natural COVID-19 infection during pregnancy leads to the passive transfer of specific anti-SARS-CoV-2 IgG antibodies to BM. These results are important to overcome vaccine hesitancy and increase vaccination levels in expectant mothers.

KEY POINTS

· We investigated the levels of SARS-CoV-2 antibodies in BM after natural infection and vaccination.. · Anti-SARS-CoV-2 IgG antibodies were detected in 39 (84.8%) BM samples.. · The highest titers in BM were found in mothers who were vaccinated following natural infection..

Viruses and Human Milk: Transmission or Protection?

Human milk (HM) is considered the best source of nutrition for infant growth and health. This nourishment is unique and changes constantly during lactation to adapt to the physiological needs of the developing infant. It is also recognized as a potential route of transmission of some viral pathogens although the presence of a virus in HM rarely leads to a disease in an infant. This intriguing paradox can be explained by considering the intrinsic antiviral properties of HM. In this comprehensive and schematically presented review, we have described what viruses have been detected in HM so far and what their potential transmission risk through breastfeeding is. We have provided a description of all the antiviral compounds of HM, along with an analysis of their demonstrated and hypothesized mechanisms of action. Finally, we have also analyzed the impact of HM pasteurization and storage methods on the detection and transmission of viruses, and on the antiviral compounds of HM. We have highlighted that there is currently a deep knowledge on the potential transmission of viral pathogens through breastfeeding and on the antiviral properties of HM. The current evidence suggests that, in most cases, it is unnecessarily to deprive an infant of this high-quality nourishment and that the continuation of breastfeeding is in the best interest of the infant and the mother.

SARS-CoV-2 Antibody Profiles in Maternal Serum and Breast Milk Following mRNA COVID-19 Vaccination: A Longitudinal Prospective Observational Cohort Study

COVID-19 vaccination during pregnancy protects infants against symptomatic COVID-19. Vaccination of lactating mothers may offer additional protection, but our understanding of immune responses in breast milk is limited. We, therefore, performed a single-center prospective cohort study of lactating mothers who received a COVID-19 mRNA primary vaccine series to evaluate the durability, breadth, and neutralizing capacity of the antibody responses in breast milk. Spike IgG- and IgA-binding antibodies of ancestral SARS-CoV-2 in serum and breast milk were quantified over 9 months using Meso Scale Discovery (MSD) V-PLEX assays, and ancestral titers were compared to four variants of concern (Alpha, Beta, Delta, Gamma) at a single time point. Neutralizing antibodies against ancestral SARS-CoV-2 and Omicron BA.4/5 were compared before and after vaccination using a pseudovirus-neutralization assay. Eleven lactating mothers received either Pfizer BNT162b2 (7/11) or Moderna mRNA-1273 (4/11) vaccine primary series. IgG and IgA titers increased in serum and breast milk following each dose, peaking 1-4 weeks after series completion. Titers remained significantly elevated for 7-9 months, except for in breast milk IgA which returned to baseline within 1 month. Furthermore, binding antibodies against all included variants were detected in breast milk collected 1-3 weeks after series completion. However, while vaccination induced a strong neutralizing response against ancestral SARS-CoV-2 in serum and more modest response in breast milk, it did not induce neutralizing antibodies against Omicron BA.4/5 in either specimen type. This study demonstrates that maternal COVID-19 mRNA vaccination may enhance immune protection for infants through breast milk via increased IgG- and IgA-binding-and-neutralizing antibodies; although, variant-specific boosters may be required to optimize immune protection.

Milk antibody response after 3rd COVID-19 vaccine and SARS-CoV-2 infection and implications for infant protection

Little is known about the persistence of human milk anti-SARS-CoV-2 antibodies after 2nd and 3rd vaccine doses and infection following 3rd dose. In this study, human milk, saliva, and blood samples were collected from 33 lactating individuals before and after vaccination and infection. Antibody levels were measured using ELISA and symptoms were assessed using questionnaires. We found that after vaccination, milk anti-SARS-CoV-2 antibodies persisted for up to 8 months. In addition, distinct patterns of human milk IgA and IgG production and higher milk RBD-blocking activity was observed after infection compared to 3-dose vaccination. Infected mothers reported more symptoms than vaccinated mothers. We examined the persistence of milk antibodies in infant saliva after breastfeeding and found that IgA was more abundant compared to IgG. Our results emphasize the importance of improving the secretion of IgA antibodies to human milk after vaccination to improve the protection of breastfeeding infants.

COVID-19 mRNA vaccine-mediated antibodies in human breast milk and their association with breast milk microbiota composition

Newborns can acquire immunological protection to SARS-CoV-2 through vaccine-conferred antibodies in human breast milk. However, there are some concerns around lactating mothers with regards to potential short- and long-term adverse events and vaccine-induced changes to their breast milk microbiome composition, which helps shape the early-life microbiome. Thus, we sought to explore if SARS-CoV-2 mRNA vaccine could change breast milk microbiota and how the changes impact the levels of antibodies in breast milk. We recruited 49 lactating mothers from Hong Kong who received two doses of BNT162b2 vaccine between June 2021 and August 2021. Breast milk samples were self-collected by participants pre-vaccination, one week post-first dose, one week post-second dose, and one month post-second dose. The levels of SARS-CoV-2 spike-specific IgA and IgG in breast milk peaked at one week post-second dose. Subsequently, the levels of both antibodies rapidly waned in breast milk, with IgA levels returning to baseline levels one month post-second dose. The richness and composition of human breast milk microbiota changed dynamically throughout the vaccination regimen, but the abundances of beneficial microbes such as Bifidobacterium species did not significantly change after vaccination. Additionally, we found that baseline breast milk bacterial composition can predict spike-specific IgA levels at one week post-second dose (Area Under Curve: 0.72, 95% confidence interval: 0.58-0.85). Taken together, our results identified specific breast milk microbiota markers associated with high levels of IgA in the breast milk following BNT162b2 vaccine. Furthermore, in lactating mothers, BNT162b2 vaccines did not significantly reduce probiotic species in breast milk.

Attitudes Toward COVID-19 Vaccination Among Pregnant Persons in Urban Hospital-Affiliated Practices: Exploring Themes in Vaccine Hesitancy

OBJECTIVE

To explore beliefs and attitudes toward the COVID-19 vaccine among vaccinated and unvaccinated pregnant persons in order to identify reasons for both vaccine hesitancy and vaccine uptake.

METHODS

From June-August 2021, we conducted a qualitative study consisting of semi-structured interviews with pregnant persons (n = 30). Participants were recruited from university-owned obstetric practices during prenatal and ultrasound appointments. Interviews were audio recorded and transcribed; transcripts were coded and analyzed to identify themes and subthemes.

RESULTS

Of the participants, one-third (n = 10) had received the COVID-19 vaccine, while two-thirds (n = 20) were unvaccinated. Primary themes for unvaccinated participants were concern about the paucity of research on the vaccine in pregnancy and potential impact of the vaccine on both fetal development and maternal health. For vaccinated participants, main themes included potential maternal and fetal protection from COVID-19 and anticipated health complications from contracting COVID-19 as their motivations to get vaccinated. While most participants cited healthcare providers as the most trusted source of vaccine information, a majority reported that the internet was their primary source of vaccine information. Many participants wanted to learn more about the COVID-19 vaccine from their obstetric providers, and notably, most vaccinated participants reported the importance of their obstetrician in their vaccine decision-making process.

CONCLUSIONS

COVID-19 vaccine hesitancy is prevalent among pregnant persons, with concerns for vaccine safety for their fetus, as well as for themselves, being common. Obstetric providers must therefore be prepared to address common concerns with patients during prenatal appointments, taking the time to actively recommend vaccination.

Breastmilk from COVID-19 negative lactating mothers shows neutralizing activity against SARS-COV-2

Breastmilk protects newborns from infections through specific and nonspecific compounds. This study investigated the neutralizing activity against SARS-CoV-2 of breastmilk from SARS-CoV-2 negative, unvaccinated mothers, and compared it to that from infected nursing mothers. We enrolled women after COVID-19 swab testing results upon maternity admission, and divided them into two groups: group A, COVID-19-positive mothers, and group B, negative mothers. Breastmilk was randomly sampled at 2, 7, and 20 days postpartum. We collected 19 samples for Group A and 41 for Group B. A microneutralization assay was used to determine the 50% neutralization (NT50) titre. The presence of neutralizing antibodies was also determined. Group A had 100% neutralizing samples at 2 days postpartum (T0), declining 7 days postpartum (T1) and 20 days postpartum (T2). Group B samples exhibited neutralizing activity mostly at 7 days postpartum (T1) (90%). Negative mothers' samples showed no correlation between NT50 titres and antibodies' presence, suggesting that non-specific breastmilk components may exert antiviral action against SARS-CoV-2.

Breastfeeding vs. breast milk transmission during COVID-19 pandemic, which is more important?

The catastrophic coronavirus disease 2019 (COVID-19) pandemic has raised many health questions, and whether breast milk from SARS-CoV-2 infected mothers may be a vector for SARS-CoV-2 transmission has become a hot topic of concern worldwide. Currently, there are extremely limited and conflicting data on the risk of infection in infants through breastfeeding. For this reason, we investigated almost all current clinical studies and systematically analyzed the presence of SARS-CoV-2 and antibodies in the breast milk of mothers infected with SARS-CoV-2, their effects on newborns, and the mechanisms involved. A total of 82 studies were included in this review, of which 66 examined the presence of SARS-CoV-2 in breast milk samples from mothers diagnosed with COVID-19, 29 reported results of antibody detection of SARS-CoV-2 in breast milk, and 13 reported both nucleic acid and antibody test results. Seventeen studies indicated the presence of detectable SARS-CoV-2 nucleic acid in breast milk samples, and only two studies monitored viral activity, both of which reported that infectious viruses could not be cultured from RNA-positive breast milk samples. All 29 studies indicated the presence of at least one of the three antibodies, IgA, IgG and IgM, in breast milk. Five studies indicated the presence of at least one antibody in the serum of breastfed newborns. No COVID-19-related deaths were reported in all 1,346 newborns. Our study suggests that direct breastfeeding does not pose an additional risk of infection to newborns and that breast milk is a beneficial source of anti-SARS-CoV-2 antibodies that provide passive immune protection to infants. In addition, direct breastfeeding would provide maternal benefits. Our review supports the recommendation to encourage direct breastfeeding under appropriate infection control guidelines. Systematic Review Registration: https://www.crd.york.ac.uk/PROSPERO/#myprospero, identifier: 458043.

Vertical transmission and maternal passive immunity post-SARS-CoV-2

Since 2020, the highly contagious nature and various transmission routes of SARS-CoV-2 have rendered the pandemic interminable. Vertical transmission (VT) through the placenta and breast milk, which is frequent for certain virus types, is thought to exist for SARS-CoV-2 and is hypothesized by many researchers. Conversely, antibodies are produced to counteract the effect of viruses. Since newborns' immunologic system cannot produce proper antibodies, maternal antibodies are usually transferred from mother to infant/fetus to meet the need. This theory leads to the hypothesis of transmission of antibodies through the placenta and breast milk following SARS-CoV-2 infection or vaccination. This paper further discusses these hypotheses, considering consequences of fetus/infant harm versus benefit.

Assessment of SARS-CoV-2 neutralizing antibody titers in breastmilk from convalescent and vaccinated mothers

Breastmilk contains antibodies that could protect breastfed infants from infections. In this work, we examined if antibodies in breastmilk could neutralize SARS-CoV-2 in 84 breastmilk samples from women that were either vaccinated (Comirnaty, mRNA-1273, or ChAdOx1), infected with SARS-CoV-2, or both infected and vaccinated. The neutralization capacity of these sera was tested using pseudotyped vesicular stomatitis virus carrying either the Wuhan-Hu-1, Delta, or BA.1 Omicron spike proteins. We found that natural infection resulted in higher neutralizing titers and that neutralization correlated positively with levels of immunoglobulin A in breastmilk. In addition, significant differences in the capacity to produce neutralizing antibodies were observed between both mRNA-based vaccines and the adenovirus-vectored ChAdOx1 COVID-19 vaccine. Overall, our results indicate that breastmilk from naturally infected women or those vaccinated with mRNA-based vaccines contains SARS-CoV-2 neutralizing antibodies that could potentially provide protection to breastfed infants from infection.

Breastfeeding provides a protective hug and the benefits have outweighed the risks during the COVID-19 pandemic

Mothers have been very hesitant about breastfeeding when they have COVID-19 infection or vaccinations. Maternal milk protects neonates through its high biological value, immune factors and anti-infectious molecules and this review shows that the virus that causes COVID-19 is not transmitted through breast milk. COVID-19 vaccines induce anti-spike antibodies with neutralising capacity, and phagocytosis, and no vaccine particles or messenger ribonucleic acid have been detected in breast milk. Most drugs used for maternal COVID-19 infections are safe for breastfed infants. CONCLUSION: The clear benefits of breastfeeding by far outweigh the very low risk of infant infections from COVID-19.

Prenatal SARS-CoV-2 infection alters postpartum human milk-derived extracellular vesicles

Human milk-derived extracellular vesicles (HMEVs) are crucial functional components in breast milk, contributing to infant health and development. Maternal conditions could affect HMEV cargos; however, the impact of SARS-CoV-2 infection on HMEVs remains unknown. This study evaluated the influence of SARS-CoV-2 infection during pregnancy on postpartum HMEV molecules. Milk samples (9 prenatal SARS-CoV-2 vs. 9 controls) were retrieved from the IMPRINT birth cohort. After defatting and casein micelle disaggregation, 1 mL milk was subjected to a sequential process of centrifugation, ultrafiltration, and qEV-size exclusion chromatography. Particle and protein characterizations were performed following the MISEV2018 guidelines. EV lysates were analyzed through proteomics and miRNA sequencing, while the intact EVs were biotinylated for surfaceomic analysis. Multi-Omics was employed to predict HMEV functions associated with prenatal SARS-CoV-2 infection. Demographic data between the prenatal SARS-CoV-2 and control groups were similar. The median duration from maternal SARS-CoV-2 test positivity to milk collection was 3 months (range: 1-6 months). Transmission electron microscopy showed the cup-shaped nanoparticles. Nanoparticle tracking analysis demonstrated particle diameters of <200 nm and yields of >1e11 particles from 1 mL milk. Western immunoblots detected ALIX, CD9 and HSP70, supporting the presence of HMEVs in the isolates. Thousands of HMEV cargos and hundreds of surface proteins were identified and compared. Multi-Omics predicted that mothers with prenatal SARS-CoV-2 infection produced HMEVs with enhanced functionalities involving metabolic reprogramming and mucosal tissue development, while mitigating inflammation and lower EV transmigration potential. Our findings suggest that SARS-CoV-2 infection during pregnancy boosts mucosal site-specific functions of HMEVs, potentially protecting infants against viral infections. Further prospective studies should be pursued to reevaluate the short- and long-term benefits of breastfeeding in the post-COVID era.

The contributions of parental lactation on offspring development: It's not udder nonsense!

The Developmental Origins of Health and Disease (DOHaD) hypothesis describes how maternal stress exposures experienced during critical periods of perinatal life are linked to altered developmental trajectories in offspring. Perinatal stress also induces changes in lactogenesis, milk volume, maternal care, and the nutritive and non-nutritive components of milk, affecting short and long-term developmental outcomes in offspring. For instance, selective early life stressors shape the contents of milk, including macro/micronutrients, immune components, microbiota, enzymes, hormones, milk-derived extracellular vesicles, and milk microRNAs. In this review, we highlight the contributions of parental lactation to offspring development by examining changes in the composition of breast milk in response to three well-characterized maternal stressors: nutritive stress, immune stress, and psychological stress. We discuss recent findings in human, animal, and in vitro models, their clinical relevance, study limitations, and potential therapeutic significance to improving human health and infant survival. We also discuss the benefits of enrichment methods and support tools that can be used to improve milk quality and volume as well as related developmental outcomes in offspring. Lastly, we use evidence-based primary literature to convey that even though select maternal stressors may modulate lactation biology (by influencing milk composition) depending on the severity and length of exposure, exclusive and/or prolonged milk feeding may attenuate the negative in utero effects of early life stressors and promote healthy developmental trajectories. Overall, scientific evidence supports lactation to be protective against nutritive and immune stressors, but the benefits of lactation in response to psychological stressors need further investigation.

Detection of SARS-CoV-2 IgA and IgG in human milk and breastfeeding infant stool 6 months after maternal COVID-19 vaccination

OBJECTIVE

Assess presence, durability, and neutralization capacity of SARS-CoV-2-specific antibodies in breastfeeding infants' stool, mother's plasma and milk following maternal vaccination.

DESIGN

Thirty-seven mothers and 25 infants were enrolled between December 2020 and November 2021 for this prospective observational study. All mothers were vaccinated during lactation except three, which were vaccinated during pregnancy. Milk, maternal plasma, and infants' stool was collected pre-vaccination and at periods up to 6 months following COVID-19 vaccine series initiation/completion. SARS-CoV-2 antibody levels and their neutralization capacities were assessed.

RESULTS

SARS-CoV-2-specific IgA and IgG levels were higher in infant stool post-maternal vaccination amongst milk-fed compared to controls. Maternal SARS-CoV-2-specific IgA and IgG concentrations decreased over 6 months post-vaccination but remained higher than pre-vaccination levels. We observed improved neutralization capacity in milk and plasma after COVID-19 vaccination.

CONCLUSIONS

The presence of SARS-CoV-2-specific antibodies in infant stool following maternal vaccination offers further evidence of the lasting transfer of these antibodies through breastfeeding.

Anti-SARS-CoV-2 Immunoglobulins in Human Milk after Coronavirus Disease or Vaccination-Time Frame and Duration of Detection in Human Milk and Factors That Affect Their Titers: A Systematic Review

Human milk (HM) of mothers infected with or vaccinated against SARS-CoV-2 contains specific immunoglobulins, which may protect their offspring against infection or severe disease. The time frame and duration after infection or vaccination, during which these immunoglobulins are detected in HM, as well as the major factors that influence their levels, have not been fully elucidated. This systematic review aimed to collect the existing literature and describe the immune response, specifically regarding the immunoglobulins in HM after COVID-19 disease or vaccination in non-immune women. We conducted a systematic search of PubMed and Scopus databases to identify studies published up until 19 March 2023. In total, 975 articles were screened, and out of which 75 were identified as being relevant and were finally included in this review. Infection by SARS-CoV-2 virus primarily induces an IgA immune response in HM, while vaccination predominantly elevates IgG levels. These immunoglobulins give HM a neutralizing capacity against SARS-CoV-2, highlighting the importance of breastfeeding during the pandemic. The mode of immune acquisition (infection or vaccination) and immunoglobulin levels in maternal serum are factors that seem to influence immunoglobulin levels in HM. Further studies are required to determine the impact of other factors, such as infection severity, lactation period, parity, maternal age and BMI on immunoglobulin level in HM.

Social Support for Breastfeeding Practice During the COVID-19 Second Wave in Thailand: A Cross-Sectional Study

BACKGROUND

Since December 2020, the second wave of COVID-19 in Thailand has had a considerable impact, and mothers have struggled to receive breastfeeding support in hospitals. In this situation, there has been limited research that addresses social support for breastfeeding and the influences of support in determining breastfeeding outcomes.

RESEARCH AIMS

(1) To describe the influence of COVID-19 on social support for breastfeeding and breastfeeding practices in the Thai context, and (2) to examine breastfeeding duration with different levels of social support from families and healthcare providers.

METHOD

This descriptive, cross-sectional online survey design was part of a larger multi-methods project about breastfeeding behaviors and experiences among postpartum mothers during the COVID-19 pandemic. Online questionnaires were administered from August to November 2021 to participants (N = 390) who were from three provinces in Thailand and had given birth 6-12 months prior to the survey.

RESULTS

Exclusive breastfeeding for 6 months was observed in less than half of the participants (n = 146, 37.4%). Perceptions of breastfeeding support were generally high overall among both family (Mdn = 45, IQR = 7) and healthcare providers (Mdn = 43, IQR = 7). Participants who perceived more breastfeeding support from families than the median had significantly longer exclusive breastfeeding durations than those who perceived less breastfeeding support than the median (z = -2.246, p = .025). The same pattern was present for breastfeeding support from healthcare providers (z = -2.380, p = 0.017).

CONCLUSIONS

While the exclusive breastfeeding rate was better than the pre-pandemic rate, successful breastfeeding was more common when participants perceived that they had received breastfeeding support. Policymakers should execute breastfeeding support systems along with COVID-19 management.

Immunisation against COVID-19 in Pregnancy and of Women Planning Pregnancy

Following reports of the first human SARS-CoV2 infection in December 2019 from Wuhan Province, China, there was such rapid spread that by March 2021, the World Health Organization (WHO) had declared a pandemic. Over 6.5 million people have died from this infection worldwide, although this is most likely an underestimate. Until vaccines became available, mortality and severe morbidity were costly in terms of life lost as well as the cost of supporting the severely and acutely ill. Vaccination changed the landscape, and following worldwide adoption, life has gradually been returning to normal. The speed of production of the vaccines was unprecedented and undoubtedly ushered in a new era in the science of fighting infections. The developed vaccines were on the already known platforms for vaccine delivery: inactivated virus, virus vector, virus-like particles (VLP) subunit, DNA and mRNA. The mRNA platform was used for the first time to deliver vaccines to humans. An understanding of these platforms and the pros and cons of each are important for clinicians who are often challenged by the recipients on the advantages and risks of these vaccines. These vaccines have so far and reassuringly been shown to be safe in reproduction (with no effect on gametes) and pregnancy (not associated with congenital malformations). However, safety remains paramount and continuing vigilance is critical, especially against rare fatal complications such as vaccine-induced thrombocytopenia and myocarditis. Finally, the waning immunity months after vaccination means repeated immunisation is likely to be ongoing, but just how often and how many such revaccinations should be recommended remains uncertain. Research into other vaccines and alternate delivery methods should continue as this infection is likely to be around for a long time.

Anti-Spike Antibodies Present in the Milk of SARS-CoV-2 Vaccinated Mothers Are Complement-Activating

Although only 0.8-1% of SARS-CoV-2 infections are in the 0-9 age-group, pneumonia is still the leading cause of infant mortality globally. Antibodies specifically directed against SARS-CoV-2 spike protein (S) are produced during severe COVID-19 manifestations. Following vaccination, specific antibodies are also detected in the milk of breastfeeding mothers. Since antibody binding to viral antigens can trigger activation of the complement classical - pathway, we investigated antibody-dependent complement activation by anti-S immunoglobulins (Igs) present in breast milk following SARS-CoV-2 vaccination. This was in view of the fact that complement could play a fundamentally protective role against SARS-CoV-2 infection in newborns. Thus, 22 vaccinated, lactating healthcare and school workers were enrolled, and a sample of serum and milk was collected from each woman. We first tested for the presence of anti-S IgG and IgA in serum and milk of breastfeeding women by ELISA. We then measured the concentration of the first subcomponents of the three complement pathways (i.e., C1q, MBL, and C3) and the ability of anti-S Igs detected in milk to activate the complement in vitro. The current study demonstrated that vaccinated mothers have anti-S IgG in serum as well as in breast milk, which is capable of activating complement and may confer a protective benefit to breastfed newborns.

Breastfeeding: crucially important, but increasingly challenged in a market-driven world

In this Series paper, we examine how mother and baby attributes at the individual level interact with breastfeeding determinants at other levels, how these interactions drive breastfeeding outcomes, and what policies and interventions are necessary to achieve optimal breastfeeding. About one in three neonates in low-income and middle-income countries receive prelacteal feeds, and only one in two neonates are put to the breast within the first hour of life. Prelacteal feeds are strongly associated with delayed initiation of breastfeeding. Self-reported insufficient milk continues to be one of the most common reasons for introducing commercial milk formula (CMF) and stopping breastfeeding. Parents and health professionals frequently misinterpret typical, unsettled baby behaviours as signs of milk insufficiency or inadequacy. In our market-driven world and in violation of the WHO International Code for Marketing of Breast-milk Substitutes, the CMF industry exploits concerns of parents about these behaviours with unfounded product claims and advertising messages. A synthesis of reviews between 2016 and 2021 and country-based case studies indicate that breastfeeding practices at a population level can be improved rapidly through multilevel and multicomponent interventions across the socioecological model and settings. Breastfeeding is not the sole responsibility of women and requires collective societal approaches that take gender inequities into consideration.

Increase in SARS-CoV-2 RBD-Specific IgA and IgG Antibodies in Human Milk From Lactating Women Following the COVID-19 Booster Vaccination

BACKGROUND

The United States Centers for Disease Control and Prevention recommended a third dose or booster of the Pfizer-BioNTech Comirnaty (BNT162b2) COVID-19 mRNA vaccine in September 2021 for high-risk individuals. Pregnant and high-risk lactating women were encouraged to receive the booster to obtain potential prolonged protection for themselves and their infants.

RESEARCH AIM

To investigate the ability of the booster vaccine to increase IgA and IgG antibodies specific to the receptor-binding domain of the SARS-CoV-2 spike protein in human milk compared to levels pre-booster.

METHODS

This was a prospective one-group study with a pretest-posttest design. Six of 12 participants were recruited prospectively. Participants were instructed to collect ≥ 2 ounces of milk in the morning at 30 days and 1-day pre-booster, and 7, 14, 21, 30, 45, and 60 days post-booster. Levels of IgA and IgG antibodies specific to the receptor-binding domain of the SARS-CoV-2 spike protein were quantified in human milk via an ELISA assay.

RESULTS

We found a significant increase in anti-receptor-binding domain-specific IgA and IgG antibodies in human milk 1-2 weeks after the Pfizer-BioNTech booster and at the study endpoint (45- and 60-days post-booster).

CONCLUSIONS

This suggests that the booster vaccination enhances SARS-CoV-2 specific immunity in human milk, which may be protective for infants.

Vaccination and treatment options for SARS-CoV2 infection affecting lactation and breastfeeding

The COVID-19 pandemic has posed considerable challenges to the health of lactating individuals. Vaccination remains one of the most important strategies for prevention of moderate to severe COVID-19 infection and is associated with protective benefits for lactating individuals and their breastfed infants with overall mild side effects. The current recommendations for COVID-19 treatment in lactating individuals includes remdesivir and dexamethasone for hospitalized patients and Paxlovid® (nirmatrelavir + ritonavir) as outpatient treatment in those with mild disease. As the pandemic continues to evolve with new COVID-19 variants, alternative therapeutic options are potentially needed, and it is critical to include lactating individuals in research to evaluate the safety and efficacy of COVID-19 treatment options in this population.

Comparing the SARS-CoV-2-specific antibody response in human milk after homologous and heterologous booster vaccinations

Human milk contains SARS-CoV-2-specific antibodies after COVID-19 vaccination. These milk antibodies decrease several months post-vaccination. Whether booster immunization restores human milk antibody levels, potentially offering prolonged passive immunity for the infant, remains unknown. In this prospective follow-up study, we investigated the longitudinal SARS-CoV-2-specific antibody response in human milk of 26 lactating women who received a COVID-19 booster dose of an mRNA-based vaccine. Moreover, we evaluated whether the booster-induced human milk antibody response differs for participants who received a similar or different vaccine type in their primary vaccination series. All participants (100%) who received a homologous booster vaccination showed SARS-CoV-2-specific immunoglobulin A (IgA) and immunoglobulin G (IgG) in their milk. Heterologous booster vaccination resulted in milk conversion for 9 (69%) and 13 (100%) participants for IgA and IgG respectively. Findings of this study indicate that both homologous and heterologous boosting schedules have the potential to enhance SARS-CoV-2-specific IgA and IgG in human milk.

Clinical characteristics of COVID-19 in hospitalized young infants and risk factors for disease severity

BACKGROUND

This study aimed to describe the clinical characteristics and severity of young infants hospitalized with COVID-19 and study the relationship between breastfeeding and maternal COVID-19 vaccination on the severity of COVID-19.

METHODS

A retrospective, observational study was performed among infants aged 6 months and below hospitalized for COVID-19 in a tertiary state hospital in Malaysia between February 1 and April 30, 2022. The primary outcome was "serious disease," defined as pneumonia requiring respiratory support or dehydration with warning signs. Multivariate logistic regression was used to determine independent predictors for serious disease.

RESULTS

A total of 102 infants were included in the study; 53.9% were males with a median age of 11 weeks (interquartile range: 5-20 weeks). Sixteen patients (15.7%) had pre-existing comorbidities, including preterm birth. Fever was the most common presenting symptom (82.4%), followed by cough (53.9%), and rhinorrhea (31.4%). Forty-one infants (40.2%) presented with serious disease, warranting either respiratory support or intravenous fluid therapy for dehydration. Recent maternal COVID-19 vaccination was associated with a reduced risk of serious disease on univariate analysis but was not significant after multivariate adjustment (adjusted odds ratio [aOR] 0.39; 95% CI: 0.14-1.11; p = 0.08). Exclusive breastfeeding was protective against serious COVID-19 in young infants, independent of other confounding factors (aOR 0.21, 95% CI: 0.06-0.71; p = 0.01).

CONCLUSION

COVID-19 is a serious disease with non-specific clinical manifestations in young infants. Exclusive breastfeeding could play an important protective role.

Passive transfer of COVID-19 immunoglobulin via breast milk post COVID-19 vaccination of lactating mother: case report and review of the literature

Infant response against infections depends largely on active and passive transfer of immunity through breast milk. There is plenty of data showing transplacental transfer of anti-severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) antibodies to the foetus and the presence of neutralising Ig-A and Ig-G anti-SARS-CoV-2 antibodies in the breast milk of mothers post COVID-19 vaccination. There is a paucity of research regarding the impact of COVID-19 vaccination of lactating mothers on the immune response in infant blood. The index case was delivered at 35 weeks of gestation with features of hydrops fetalis. The COVID-19 rapid antigen test and COVID-19 reverse transcription-polymerase chain reaction test were negative for the mother and neonate. The baby was investigated for sepsis, underwent double volume exchange transfusion, and was discharged on exclusive breastfeeding. SARS-CoV-2 antibody titres were tested in blood and breast milk samples 4 weeks after first and second dose of the COVID-19 vaccination of the mother. Growth, neurodevelopment and haematological parameters were monitored over time. A robust immune response was reported in the blood of infants post COVID-19 vaccination of the mother with the potential to confer passive immunity to the baby and without any serious side effects in the mother-infant dyad.

A large series of molecular and serological specimens to evaluate mother-to-child SARS-CoV-2 transmission: a prospective study from the Italian Obstetric Surveillance System

OBJECTIVES

To assay the presence of the SARS-CoV-2 genome in vaginal, rectal, and placental swabs among pregnant women and in newborn nasopharyngeal swabs and to investigate the immunological response and maternal antibody transfer through the umbilical cord blood and milk of unvaccinated mothers.

METHODS

Vaginal, rectal, and placental specimens, maternal and neonatal serum, and milk were collected from a wide cohort of pregnant Italian women with confirmed SARS-CoV-2 infection admitted to the hospital between February 25, 2020 and June 30, 2021. Samples were tested in selected reference laboratories according to a shared interlaboratory protocol.

RESULTS

Among 1086 enrolled women, the SARS-CoV-2 positive rate detected in all specimens ranged from 0.7% to 8.4%. Respectively, 45.2% of maternal sera collected during pregnancy and 39.7% of those collected at birth tested positive for immunoglobulin G, whereas 50.5% tested positive among neonates. Nasopharyngeal swabs were positive in 0.8% of the newborns, and immunoglobulin G was detected in 3.0% of the milk samples. The highest immunological response was recorded within 30 days during pregnancy and within 60 days of birth and in the neonatal population.

CONCLUSION

Vertical transmission should be considered a rare event; although, a good maternal immunological response and antibodies transfer throughout the umbilical cord blood was detected.

COVID-19 Vaccines during Pregnancy and Breastfeeding: A Systematic Review

Background: Pregnant and breastfeeding women received unclear recommendations regarding COVID-19 vaccination at the beginning of the pandemic, as they were not included in the initial clinical trials. This systematic review aims to provide an update regarding COVID-19 vaccines during pregnancy and breastfeeding. Methods: The systematic review was carried out through a literature search in Medline/Pubmed. Studies were selected if they included information regarding COVID-19 vaccination during pregnancy and breastfeeding. The PRISMA guidelines for systematic reviews were followed. Results: A total of 33 studies were included. The main adverse effect is pain at the injection site, as in the general population. Adverse effects are more frequent after the second dose, being slightly more frequent after the Moderna vaccine. COVID-19 vaccination reduces the risk of severe COVID-19 in pregnant women. Additionally, COVID-19 vaccination induces artificial active immunogenicity in the mother and natural passive immunogenicity in the child. Breastmilk straddles both immediate antibody-mediated and long-lived cellular-mediated immune protection. Regarding neonatal benefits, vaccination is associated with a larger and more stable Immunoglobulin G response, while COVID-19 Infection is associated with a rapid and long-lasting Immunoglobulin A response. Conclusions: COVID-19 vaccines are not only suggested but strongly recommended for pregnant and breastfeeding populations to protect mothers and newborns.

SARS-CoV-2 spike RBD-specific IgA and IgG antibodies in breast milk after vaccination with the protein subunit vaccine Abdala

Background

COVID-19 vaccines that trigger a strong secretory antibody response in breast milk may achieve effective passive protection of vulnerable newborns and breastfed infants of immunized mothers. The aim of this work was to investigate the presence of SARS-CoV-2 spike RBD-specific IgA and IgG antibodies in breast milk, 5 and 9 weeks after vaccination with 3 doses of the protein subunit vaccine Abdala, compared to those found in breast milk from COVID-19-recovered women, collected at least 40 days after the infection.

Methods

SARS-CoV-2 spike RBD-specific IgA and IgG antibodies were semi-quantified by indirect ELISA, using a homemade standard generated by pooling twenty breast milk samples with high absorbance values according to preliminary data. The validity of the standard curves was proved following the European Medicines Agency Guideline. Two breast milk samples from 2 unvaccinated women who had not been infected with COVID-19 were included as negative controls. Potentially neutralizing antibodies was assessed by a SARS-CoV-2 surrogate virus neutralization test.

Results

High levels of anti-RBD IgA antibodies were detected in breast milk samples 9 weeks after vaccination and anti-RBD IgG antibodies rise from the fifth to the ninth week. In the post-COVID-19 time that was evaluated, the IgG-type response was notably higher compared to both post-vaccination periods. Neutralizing antibody titers were similar in breast milk from vaccinated and COVID-19 recovered women.

Conclusions

This is the first report about the immune response in breast milk after the administration of a COVID-19 protein subunit vaccine, which could provide analogous protection to that conferred by SARS-CoV-2 infection. This implies a potential passive immunity that breastfed infants receive from their mothers vaccinated with Abdala.

Combined monitoring of IgG and IgA anti-Spike and anti-Receptor binding domain long term responses following BNT162b2 mRNA vaccination in Greek healthcare workers

Studies on the humoral response to homologous BNT162b2 mRNA-vaccination focus mainly on IgG antibody dynamics, while long-term IgA kinetics are understudied. Herein, kinetics of IgG and IgA levels against trimeric-Spike (S) and Receptor-Binding-Domain (RBD) were evaluated by in-house ELISAs in 146 two-dose vaccinated Greek healthcare workers (HCWs) in a 9-month period at six time points (up to 270 days after the first dose). The effect of a homologous booster third dose was also studied and evaluated. The peak of immune response was observed 21 days after the second dose; 100% seroconversion rate for anti-S and anti-RBD IgG, and 99.7% and 96.3% respectively for IgA. IgG antibody levels displayed higher increase compared to IgA. Declining but persistent anti-SARS-CoV-2 antibody levels were detected 9 months after vaccination; IgG and IgA anti-S levels approached those after the first dose, while a more rapid reduction rate for anti-RBD antibodies led to significantly lower levels for both classes, supporting the need for a booster dose. Indeed, a homologous booster third dose resulted in enhanced levels of anti-S of both classes, whereas anti-RBD didn't exceed the peak levels after the second dose. Previous SARS-CoV-2 infection, flu vaccination, BMI<35 and the occurrence of an adverse event upon vaccination, were associated with higher IgG antibody levels over time, which however were negatively affected by age increase and the presence of chronic diseases. Overall, after concurrently using the S and RBD target-antigens in in-house ELISAs, we report in addition to IgG, long-term persistence of IgA antibodies. Regarding antibody levels, homologous mRNA vaccination gives rise to an effective anti-viral protection up to 9 months negatively correlated to age. Considering that COVID-19 is still a matter of public concern, booster vaccine doses remain critical to vulnerable individuals.

Pandemic policies and breastfeeding: A cross-sectional study during the onset of COVID-19 in the United States

The United States is one of the few countries, and the only high-income country, that does not federally mandate protection of postpartum employment through paid postpartum maternity and family leave policies. At the onset of the COVID-19 pandemic in the U.S., stay-at-home orders were implemented nationally, creating a natural experiment in which to document the effects of de facto paid leave on infant feeding practices in the first postpartum year. The purpose of this cross-sectional, mixed-methods study was to describe infant and young child feeding intentions, practices, decision-making, and experiences during the first wave of the COVID-19 pandemic in the U.S. Quantitative and qualitative data were collected March 27-May 31, 2020 via online survey among a convenience sample of respondents, ages 18 years and older, who were currently feeding a child 2 years of age or younger, yielding 1,437 eligible responses. Nearly all (97%) respondents indicated an intention to feed their infant exclusively with human milk in the first 6 months. A majority of respondents who were breastfeeding (66%) reported no change in breastfeeding frequency after the implementation of COVID-19 stay-at-home orders. However, thirty-one percent indicated that they breastfed more frequently due to stay-at-home orders and delayed plans to wean their infant or young child. Key themes drawn from the qualitative data were: emerging knowledge and perceptions of the relationship between COVID-19 and breastfeeding, perceptions of immune factors in human milk, and the social construction of COVID-19 and infant and young child feeding perceptions and knowledge. There were immediate positive effects of stay-at-home policies on human milk feeding practices, even during a time of considerable uncertainty about the safety of breastfeeding and the transmissibility of SARS-CoV-2 via human milk, constrained access to health care services and COVID-19 testing, and no effective COVID-19 vaccines. Federally mandated paid postpartum and family leave are essential to achieving more equitable lactation outcomes.

SARS-CoV-2 specific antibody trajectories in mothers and infants over two months following maternal infection

Infants exposed to caregivers infected with SARS-CoV-2 may have heightened infection risks relative to older children due to their more intensive care and feeding needs. However, there has been limited research on COVID-19 outcomes in exposed infants beyond the neonatal period. Between June 2020 - March 2021, we conducted interviews and collected capillary dried blood spots from 46 SARS-CoV-2 infected mothers and their infants (aged 1-36 months) for up to two months following maternal infection onset (COVID+ group, 87% breastfeeding). Comparative data were also collected from 26 breastfeeding mothers with no known SARS-CoV-2 infection or exposures (breastfeeding control group), and 11 mothers who tested SARS-CoV-2 negative after experiencing symptoms or close contact exposure (COVID- group, 73% breastfeeding). Dried blood spots were assayed for anti-SARS-CoV-2 S-RBD IgG and IgA positivity and anti-SARS-CoV-2 S1 + S2 IgG concentrations. Within the COVID+ group, the mean probability of seropositivity among infant samples was lower than that of corresponding maternal samples (0.54 and 0.87, respectively, for IgG; 0.33 and 0.85, respectively, for IgA), with likelihood of infant infection positively associated with the number of maternal symptoms and other household infections reported. COVID+ mothers reported a lower incidence of COVID-19 symptoms among their infants as compared to themselves and other household adults, and infants had similar PCR positivity rates as other household children. No samples returned by COVID- mothers or their infants tested antibody positive. Among the breastfeeding control group, 44% of mothers but none of their infants tested antibody positive in at least one sample. Results support previous research demonstrating minimal risks to infants following maternal COVID-19 infection, including for breastfeeding infants.

SARS-CoV-2-Specific IgG and IgA response in maternal blood and breastmilk of vaccinated naïve and convalescent lactating participants

Background

Recent studies have shown the presence of SARS-CoV-2-specific antibodies in the milk of breastfeeding mothers vaccinated with mRNA and convalescent. However, limited information is available in lactating women receiving other vaccine platforms used in developing countries, such as the inactivated SARS-CoV-2 vaccine BBIBP-CorV (Sinopharm) and the non-replicating adenovirus vaccines Sputnik V (Gamaleya Institute) and ChAdOx1-S (Oxford AstraZeneca).

Methods

Here, we evaluated anti-SARS-CoV-2 IgG and IgA levels in both serum and milk samples using a longitudinal and a cross-sectional cohort of 208 breastfeeding vaccinated women from Argentina with or without previous SARS-CoV-2 infection.

Results

The analysis showed that IgA levels remain constant in serum and milk of breastfeeding mothers between the first and second doses of vector-based vaccines (Sputnik V and ChAdOx1-S). After the second dose, anti-spike IgA was found positive in 100% of the serum samples and in 66% of breastmilk samples. In addition, no significant differences in milk IgA levels were observed in participants receiving BBIBP-CorV, Sputnik V or ChAdOx1-S. IgG levels in milk increased after the second dose of vector-based vaccines. Paired longitudinal samples taken at 45 and 120 days after the second dose showed a decrease in milk IgG levels over time. Study of IgA levels in serum and milk of vaccinated naïve of infection and vaccinated-convalescent breastfeeding participants showed significantly higher levels in vaccinated-convalescent than in participants without previous infection.

Conclusion

This study is relevant to understand the protection against SARS-CoV-2 by passive immunity in newborns and children who are not yet eligible to receive vaccination.

COVID-19 Vaccine Acceptance during Pregnancy and Influencing Factors in South Korea

Pregnant women were excluded from vaccination against Coronavirus 2019 (COVID-19) until September 2021 in South Korea. Although vaccination for pregnant women started in October 2021, vaccine acceptance in pregnant women is yet unknown. This cross-sectional study aimed to investigate COVID-19 vaccine acceptance during pregnancy and influencing factors. An anonymous survey was distributed in obstetrics departments to all pregnant or postpartum women, during the prenatal or postpartum visit. The proportion of self-reported COVID-19 vaccination during pregnancy among 436 women was 26.6%. Pregnancy-related independent factors influencing maternal COVID-19 vaccination were “received vaccine information about from obstetrics and gynecology (OBGYN) doctors” (OR 3.41, 95% CI 2.05–5.65), “cohabitant COVID-19 vaccination” (OR 2.43, 95% CI 1.06–5.59), and “second trimester” (OR 7.35, 95% CI 1.54–35.15). In women who did not want to get vaccinated, the most common reason for COVID-19 vaccination hesitancy was concern that COVID-19 vaccine might affect the fetus (91.7%, 243/266), followed by distrust in COVID-19 vaccine effectiveness (42.6%, 113/266). This study showed that providing information about maternal COVID-19 vaccination, especially by OBGYN doctors, is crucial for increasing vaccination coverage in pregnant women. Providing updated evidence of COVID-19 vaccine efficacy and safety in pregnant women may be also helpful for increasing vaccine acceptance.

Durable antibody and effector memory T cell responses in breastmilk from women with SARS-CoV-2

Background

Given that only 25% of pregnant women elect to receive a COVID-19 vaccine, maternal SARS-CoV-2 infection remains an important route of conferring protective passive immunity to breastfed infants of mothers who are not vaccinated.

Methods

We enrolled 30 lactating participants between December 2020 and March 2021 who had a positive PCR-test and their first COVID-19 symptoms within the previous 21 days. Participants were asked to provide serial bilateral milk samples at 12 timepoints (~ every 3 days) over a period of 35 days. A second set of samples was collected at least four months after the beginning of the first set. Participants also were asked to provide their dried blood spots and infant stool samples. All samples were tested for receptor-binding domain (RBD)-specific immunoglobulin (Ig)A, IgG, and IgM. Milk samples were assessed for neutralizing ability against the spike protein and four SARS-CoV-2 variants: D614G, Alpha (B.1.1.7), Beta (B.1.351), and Gamma (P.1). Permeability of the breast epithelium was assessed by measuring the sodium to potassium ions (Na:K) in milk. Using flow cytometry, memory CD4 and CD8 T cells (CD45RO+ and CCR7+/-) and mucosal-homing CD4 and CD8 T cells (CD103+) were determined in cells from milk expressed at 35 days and at least 4 months after their first milk donation.

Results

Milk antibodies from SARS-CoV-2 positive participants neutralized the spike complex. Milk from 73, 90, and 53% of participants had binding reactivities to RBD-specific IgA, IgG, and IgM, respectively. In contrast to blood spots, which showed increased levels of IgG, but not IgA or IgM, the COVID-19 response in milk was associated with a robust IgA response. Twenty-seven percent of participants had increased breast-epithelium permeability, as indicated by Na:K ≥ 0.6. The percentage of CD45RO+CCR7- effector-memory T cells in the day ≥120 milk samples was significantly higher than day 35 samples (P< 0.05).

Conclusions

Antibodies in milk from participants with recent SARS-CoV-2 infection and those who recovered can neutralize the spike complex. For the first time we show that breastmilk T cells are enriched for mucosal memory T cells, further emphasizing the passive protection against SARS-CoV-2 conferred to infants via breastmilk.

Gut microbiome and breast-feeding: Implications for early immune development

Establishment of the gut microbiome during early life is a complex process with lasting implications for an individual's health. Several factors influence microbial assembly; however, breast-feeding is recognized as one of the most influential drivers of gut microbiome composition during infancy, with potential implications for function. Differences in gut microbial communities between breast-fed and formula-fed infants have been consistently observed and are hypothesized to partially mediate the relationships between breast-feeding and decreased risk for numerous communicable and noncommunicable diseases in early life. Despite decades of research on the gut microbiome of breast-fed infants, there are large scientific gaps in understanding how human milk has evolved to support microbial and immune development. This review will summarize the evidence on how breast-feeding broadly affects the composition and function of the early-life gut microbiome and discuss mechanisms by which specific human milk components shape intestinal bacterial colonization, succession, and function.

The Effects of COVID-19 Hospital Practices on Breastfeeding Initiation and Duration Postdischarge

Background: Early in the COVID-19 pandemic, many birth hospitals separated SARS-CoV-2-positive mothers from their newborn infants and advised against breastfeeding to decrease postnatal SARS-CoV-2 transmission. Information on how these practices impacted breastfeeding postdischarge is limited. Objectives: In a statewide sample of SARS-CoV-2-positive mothers, we aimed to determine the extent to which (1) mother-infant separation and (2) a lack of breastfeeding initiation in-hospital were associated with breast milk feeding postdischarge. Design/Methods: From 11 birthing hospitals in Massachusetts, we identified 187 women who tested positive for SARS-CoV-2 from 14 days before to 72 hours after delivery (March 1-July 31, 2020) and their newborn infants. We abstracted chart data from the delivery hospitalization on main exposure variables (mother-infant separation, in-hospital breast milk feeding [expressed milk feeding and/or direct breastfeeding]) and from outpatient visits until 30 days postdischarge. We evaluated associations of in-hospital practices with outcomes up to 30 days postdischarge, adjusting for confounders using multivariable logistic and linear regression. Results: Mother-infant separation in-hospital was associated with a shorter duration of any breast milk feeding (regression coefficient estimate -5.29 days, 95% confidence intervals [CI] [-8.89 to -1.69]). Direct breastfeeding in-hospital was associated with higher odds of any breast milk feeding (adjusted odds ratios [AOR] 5.68, 95% CI [1.65-23.63]) and direct breastfeeding (AOR 8.19, 95% CI [2.99-24.91]) postdischarge; results were similar for any breast milk feeding in-hospital. Conclusions: Perinatal hospital care practices implemented early in the COVID-19 pandemic, specifically mother-infant separation and prevention of breast milk feeding initiation, were associated with adverse effects on breast milk feeding outcomes assessed up to 1 month postdischarge.

Nutrition as Personalized Medicine against SARS-CoV-2 Infections: Clinical and Oncological Options with a Specific Female Groups Overview

Coronavirus disease 2019 (COVID-19) is a respiratory disease caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). It is acknowledged that vulnerable people can suffer from mortal complications of COVID-19. Therefore, strengthening the immune system particularly in the most fragile people could help to protect them from infection. First, general nutritional status and food consumption patterns of everyone affect the effectiveness of each immune system. The effects of nutrition could impact the level of intestinal and genital microbiota, the adaptive immune system, and the innate immune system. Indeed, immune system cells and mediators, which are crucial to inflammatory reaction, are in the structures of fats, carbohydrates, and proteins and are activated through vitamins (vit) and minerals. Therefore, the association of malnutrition and infection could damage the immune response, reducing the immune cells and amplifying inflammatory mediators. Both amount and type of dietary fat impact on cytokine biology, that consequently assumes a crucial role in inflammatory disease. This review explores the power of nutrition in the immune response against COVID-19 infection, since a specific diet could modify the cytokine storm during the infection phase. This can be of vital importance in the most vulnerable subjects such as pregnant women or cancer patients to whom we have deemed it necessary to dedicate personalized indications.

Human Milk Antibody Response After Combining Two Different COVID-19 Vaccines: Mix-and-Match

BACKGROUND

SARS-CoV-2-specific antibodies are secreted into human milk after women are vaccinated against COVID-19, which might protect the breastfed infant. Due to several reports of severe side-effects of the Oxford-AstraZeneca ChAdOx1 (AZD1222) vaccine against COVID-19, some lactating women followed a heterologous vaccination schedule consisting of the first dose of AZD1222 and a second dose of an mRNA-based vaccine. However, it is unclear whether this generates a significant SARS-CoV-2-specific antibody response in human milk.

MAIN ISSUE

To quantify the SARS-CoV-2-specific antibody response in human milk of two lactating women receiving a heterologous vaccination schedules: AZD1222 and mRNA-based vaccine (Pfizer-BioNTech [BNT162b2] and Moderna [mRNA-1273]).

MANAGEMENT

Both participants collected 16 samples of human milk longitudinally. SARS-CoV-2-specific Immunoglobulin A was measured using an enzyme-linked immunosorbent assay.

CONCLUSION

Based on our results, it could be suggested that heterologous vaccination with AZD1222 and an mRNA-based vaccine can elicit a significant SARS-CoV-2 specific IgA response in human milk.

Safety and protective capability of an inactivated SARS-CoV-2 vaccine on pregnancy, lactation and the growth of offspring in hACE2 mice

The mass inoculation of a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine to induce herd immunity is one of the most effective measures to fight COVID-19. The vaccination of pregnant women cannot only avoid or reduce the probability of infectious diseases, but also offers the most effective and direct protection for neonates by means of passive immunization. However, there is no randomized clinical data to ascertain whether the inactivated vaccination of pregnant women or women of childbearing age can affect conception and the fetus. We found that human angiotensin-converting enzyme 2 (hACE2) mice that were vaccinated with two doses of CoronaVac (an inactivated SARS-CoV-2 vaccine) before and during pregnancy exhibited normal weight changes and reproductive performance indices; the physical development of their offspring was also normal. Following intranasal inoculation with SARS-CoV-2, pregnant mice in the immunization group all survived; reproductive performance indices and the physical development of offspring were all normal. In contrast, mice in the non-immunization group all died before delivery. Analyses showed that inoculation of CoronaVac was safe and did not exert any significant effects on pregnancy, lactation, or the growth of offspring in hACE2 mice. Vaccination effectively protected the pregnant mice against SARS-CoV-2 infection and had no adverse effects on the growth and development of the offspring, thus suggesting that inoculation with an inactivated SARS-CoV-2 vaccine may be an effective strategy to prevent infection in pregnant women.

Effects of Vaccination Against Influenza, Pertussis, and COVID-19 on Human Milk Antibodies: Current Evidence and Implications for Health Equity

Human milk contains three antibody classes that confer mucosal immunity to the breastfed infant: secretory IgA (SIgA), secretory IgM (SIgM), and IgG. Influenza and pertussis vaccines administered during pregnancy induce pathogen specific SIgA and IgG responses in human milk that have been shown to protect the breastfed infant from these respiratory illnesses. In addition, mRNA vaccines against the SARS-CoV-2 virus administered during pregnancy and lactation induce anti-SARS-CoV-2 IgG and IgA responses in human milk. This review summarizes the immunologic benefits of influenza, pertussis, and COVID-19 vaccines conferred by human milk. Additionally, future research direction in human milk immunity and public health needs to improve lactational support are discussed.

Humoral response to anti-SARS-CoV-2 vaccine in breastfeeding mothers and mother-to-infant antibody transfer through breast milk

The magnitude of mother-to-infant transfer of anti-SARS-CoV-2 antibodies through breast milk (BM) after maternal vaccination during breastfeeding, in the absence of transplacental transfer of IgG, remains unclear. Here, we quantified anti-S and anti-RBD IgG, IgA, IgA1, and IgA2 in maternal serum, maternal saliva, BM, infant buccal swabs, and infant feces up to 90 days after the second maternal vaccine dose. BNT162b2 vaccine induced long-lasting IgG in maternal serum, but weaker mucosal antibody production, with anti-SARS-CoV-2 IgG and IgA amounts in BM between 10- and 150-fold lower compared to serum. BM IgA were exclusively of the IgA1 isotype, with no production of the mucosal-specific and protease-resistant IgA2. Accordingly, only traces of antibodies were retrieved from the feces of breastfed infants, and no IgG nor IgA were retrieved from infants' buccal swabs. Newly engineered anti-SARS-CoV-2 vaccines may be needed to stimulate the antibody production at mucosal sites such as breast milk.

Centering the Right to Health of Childbearing People in the US During the COVID-19 Pandemic

Childbearing people in the US have experienced the double burden of increased risks from infection and significant disruptions to access and quality of essential health care services during the COVID pandemic. A single person could face multiple impacts across the course of their reproductive trajectory. We highlight how failure to prioritize this population in the COVID-19 policy response have led to profound disruptions from contraception services to vaccination access, which violate foundational principles of public health, human rights and perpetuate inequities. These disruptions continued through the omicron surge, during which many health systems became overwhelmed and re-imposed earlier restrictions. We argue that an integrated pandemic response that prioritizes the healthcare needs and rights of childbearing people must be implemented to avoid deepening inequities in this and future pandemics.

Overview of Breastfeeding Under COVID-19 Pandemic

During the global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), pregnant and lactating women are at higher risk of infection. The potential of viral intrauterine transmission and vertical transmission by breastfeeding has raised wide concerns. Breastmilk is rich in nutrients that contribute to infant growth and development, and reduce the incidence rate of infant illness and death, as well as inhibit pathogens significantly, and protect infants from infection. Although it is controversial whether mothers infected with COVID-19 should continue to breastfeed, many countries and international organizations have provided recommendations and guidance for breastfeeding. This review presents the risks and benefits of breastfeeding for mothers infected with COVID-19, and the reasons for the absence of SARS-CoV-2 active virus in human milk. In addition, the antiviral mechanisms of nutrients in breastmilk, the levels of SARS-CoV-2 specific antibodies in breastmilk from COVID-19 infected mothers and vaccinated mothers are also summarized and discussed, aiming to provide some support and recommendations for both lactating mothers and infants to better deal with the COVID-19 pandemic.