Born into an isolating world: family-centred care for babies born to mothers with COVID-19.

Background: The benefits of facilitating breastmilk feeding and close contact between mother and neonate (family-centred care; FCC) in the perinatal period are well-established. The aim of this study was to determine how the delivery of FCC practices were impacted for neonates born to mothers with perinatal SARS-CoV-2 infection during the COVID-19 pandemic. Methods: Neonates born to mothers with confirmed SARS-CoV-2 infection during pregnancy were identified from the 'EsPnIC Covid paEdiatric NeonaTal REgistry' (EPICENTRE) multinational cohort between 10 March 2020 and 20 October 2021. The EPICENTRE cohort collected prospective data on FCC practices. Rooming-in and breastmilk feeding practice were the main outcomes, and factors influencing each were determined. Other outcomes included mother-baby physical contact prior to separation and the pattern of FCC components relative to time and local site guidelines. Findings: 692 mother-baby dyads (13 sites, 10 countries) were analysed. 27 (5%) neonates were positive for SARS-CoV-2 (14 (52%) asymptomatic). Most sites had policies that encouraged FCC during perinatal SARS-CoV-2 infection for most of the reporting period. 311 (46%) neonates roomed-in with their mother during the admission. Rooming-in increased over time from 23% in March-June 2020 to 74% in January-March 2021 (boreal season). 330 (93%) of the 369 separated neonates had no FCC physical contact with their mother prior, and 319 (86%) were asymptomatic. Maternal breastmilk was used for feeding in 354 (53%) neonates, increasing from 23% to 70% between March-June 2020 and January-March 2021. FCC was most impacted when mothers had symptomatic COVID-19 at birth. Interpretation: This is the largest report of global FCC practice during the COVID-19 pandemic to date. The COVID-19 pandemic may have impacted FCC despite low perinatal transmission rates. Fortunately, clinicians appear to have adapted to allow more FCC delivery as the COVID-19 pandemic progressed. Funding: The National Health and Medical Research Council (Australia): Grant ID 2008212 (DGT), Royal Children's Hospital Foundation: Grant ID 2019-1155 (EJP), Victorian Government Operational Infrastructure Support Program.

Sequential interventions to maintain the safety and service provisions of human milk banking in India: keeping up with the call to action in response to the COVID-19 pandemic.

BACKGROUND: WHO recommends donor milk as the next best choice if Mothers' own milk (MOM) is unavailable. At our milk bank, during the COVID 19 pandemic, we observed a steep decline in the collection of donor milk, while Pasteurised Donor human milk (PDHM) demand increased. This called for active intervention. METHODS: We employed the quasi-experimental quality improvement initiative. During September 2020 (baseline period) the team members identified modifiable bottlenecks and suggested interventions (using WhatsApp to increase follow up, telehealth and digital tools) which were implemented in October 2020 and the impact was evaluated till March 2021. The SMART aim was "to meet the demand (estimated as 15,000 ml/month) of donor milk for adjoining 80-bedded NICU". Process measures were; daily amount of donor milk collected, pasteurized donor milk disbursed to NICU, number of donors and frequency of donations. The balancing measure was that the collection of donor milk should not undermine the provision of freshly expressed MOM for babies. RESULTS: Collection of donor milk increased by 180% from baseline during the Intervention phase. This was sustained throughout the sustenance phase (November 2020 and March 2021) with an average monthly collection of 16,500 ml. Strikingly, the increased follow-up of mothers with emphasis on MOM decreased the NICU's donor milk requirement from 13,300 ml (baseline) to 12,500 ml (intervention) to 8,300 ml (sustenance). Monitoring of daily MOM used in the NICU revealed a 32% surge from 20,000 ml (baseline) to 27,000 ml (intervention) sustained at 25,000 ml per month. CONCLUSION: By improving the provisions of human milk banks, near-exclusive human milk feeding can be ensured even during the pandemic time.

Impact of the Coronavirus Disease (COVID-19) Pandemic on Neonatal Nutrition: Focus on Low- and Middle-Income Countries.

Purpose of Review: This review serves to account for the published literature regarding the changing impact of the COVID-19 pandemic with a focus on neonatal nutrition in low- and middle-income countries. Recent Findings: Initial national and international guidelines regarding breastfeeding were often contradictory. Lack of clear guidelines resulted in separation of mother-neonate dyads and the reliance on non-human sources of milk at institutional levels. Mothers and families were less likely to initiate and/or continue breastfeed during the pandemic due to confusion regarding guidelines, lack of support for lactation, and concern for infection transmission to their neonates. Continued research in neonatal nutrition, however, continues to support the use of breastmilk as the optimal nutritional source for neonates. Summary: Despite concerns for increased risk of COVID-19 transmission with breastfeeding, the use of breastmilk with preserved and combined mother-baby care is associated with improved neonatal nutrition.

Cytokines and Chemokines in Breastmilk of SARS-CoV-2 Infected or COVID-19 Vaccinated Mothers.

INTRODUCTION: The COVID-19 disease and anti-SARS-CoV-2 vaccination were accompanied by alterations in several inflammatory markers. The aim of our research was to check to what extent such cytokines are transferred to infants via the breastmilk of SARS-CoV-2-infected or vaccinated mothers. Thus, we wanted to check if breastfeeding is safe during SARS-CoV-2 infection or after COVID-19 mRNA-vaccination. MATERIAL AND METHOD: The Luminex Multiplexing Assay was used for quantifying 10 cytokine in the human breastmilk of SARS-CoV-2-infected or COVID-19-vaccinated mothers, compared with anti-SARS-CoV-2 IgG naïve mothers. Two milk samples were collected at 30 and 60 days either after the booster dose or afterthe onset of symptoms. A single milk sample was collected from the mothers within the control group. RESULTS: The cytokine concentrations were mostly found within the reference intervals for all mothers. The status of the vaccinated/infected mother, the age of the breastfed child, the parity of the mother and the maternal age were variation factors of the above-mentioned cytokine concentrations. The type of birth and the presence of IgG in the milk had no influence on these cytokine concentrations in milk. Furthermore, no statistically significant differences were recorded between the cytokine concentrations of the two milk samples. CONCLUSION: Our study provides data that support the safety of breastfeeding in the case of mild COVID-19 infection or after Pfizer or Moderna vaccinations.

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 pandemic-related change in racial and ethnic disparities in exclusive breastmilk feeding during the delivery hospitalization: a differences-in-differences analysis.

OBJECTIVE: Exclusive breastmilk feeding during the delivery hospitalization, a Joint Commission indicator of perinatal care quality, is associated with longer-term breastfeeding success. Marked racial and ethnic disparities in breastfeeding exclusivity and duration existed prior to COVID-19. The pandemic, accompanied by uncertainty regarding intrapartum and postpartum safety practices, may have influenced disparities in infant feeding practices. Our objective was to examine whether the first wave of the COVID-19 pandemic in New York City was associated with a change in racial and ethnic disparities in exclusive breastmilk feeding during the delivery stay. METHODS: We conducted a cross-sectional study of electronic medical records from 14,964 births in two New York City hospitals. We conducted a difference-in-differences (DID) analysis to compare Black-white, Latina-white, and Asian-white disparities in exclusive breastmilk feeding in a pandemic cohort (April 1-July 31, 2020, n=3122 deliveries) to disparities in a pre-pandemic cohort (January 1, 2019-February 28, 2020, n=11,842). We defined exclusive breastmilk feeding as receipt of only breastmilk during delivery hospitalization, regardless of route of administration. We ascertained severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection status from reverse transcription-polymerase chain reaction tests from nasopharyngeal swab at admission. For each DID model (e.g. Black-white disparity), we used covariate-adjusted log binomial regression models to estimate racial and ethnic risk differences, pandemic versus pre-pandemic cohort risk differences, and an interaction term representing the DID estimator. RESULTS: Exclusive breastmilk feeding increased from pre-pandemic to pandemic among white (40.8% to 46.6%, p<0.001) and Asian (27.9% to 35.8%, p=0.004) women, but not Black (22.6% to 25.3%, p=0.275) or Latina (20.1% to 21.4%, p=0.515) women overall. There was an increase in the Latina-white exclusive breastmilk feeding disparity associated with the pandemic (DID estimator=6.3 fewer cases per 100 births (95% CI=-10.8, -1.9)). We found decreased breastmilk feeding specifically among SARS-CoV-2 positive Latina women (20.1% pre-pandemic vs. 9.1% pandemic p=0.013), and no change in Black-white or Asian-white disparities. CONCLUSIONS: We observed a pandemic-related increase in the Latina-white disparity in exclusive breastmilk feeding, urging hospital policies and programs to increase equity in breastmilk feeding and perinatal care quality during and beyond this health emergency.

Human Milk Extracellular Vesicles: A Biological System with Clinical Implications.

The consumption of human milk by a breastfeeding infant is associated with positive health outcomes, including lower risk of diarrheal disease, respiratory disease, otitis media, and in later life, less risk of chronic disease. These benefits may be mediated by antibodies, glycoproteins, glycolipids, oligosaccharides, and leukocytes. More recently, human milk extracellular vesicles (hMEVs) have been identified. HMEVs contain functional cargos, i.e., miRNAs and proteins, that may transmit information from the mother to promote infant growth and development. Maternal health conditions can influence hMEV composition. This review summarizes hMEV biogenesis and functional contents, reviews the functional evidence of hMEVs in the maternal-infant health relationship, and discusses challenges and opportunities in hMEV research.

Severe Acute Respiratory Syndrome Coronavirus 2 Infection Versus Vaccination in Pregnancy: Implications for Maternal and Infant Immunity.

BACKGROUND: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection has been associated with adverse maternal and neonatal outcomes, yet uptake of SARS-CoV-2 vaccines during pregnancy and lactation has been slow. As a result, millions of pregnant and lactating women and their infants remain susceptible to the virus. METHODS: We measured spike-specific immunoglobulin G (anti-S IgG) and immunoglobulin A (anti-S IgA) in serum and breastmilk (BM) samples from 3 prospective mother-infant cohorts recruited in 2 academic medical centers. The primary aim was to determine the impact of maternal SARS-CoV-2 immunization vs infection and their timing on systemic and mucosal immunity. RESULTS: The study included 28 mothers infected with SARS-CoV-2 in late pregnancy (INF), 11 uninfected mothers who received 2 doses of the BNT162b2 vaccine in the latter half of pregnancy (VAX-P), and 12 uninfected mothers who received 2 doses of BNT162b2 during lactation. VAX dyads had significantly higher serum anti-S IgG compared to INF dyads (P < .0001), whereas INF mothers had higher BM:serum anti-S IgA ratios compared to VAX mothers (P = .0001). Median IgG placental transfer ratios were significantly higher in VAX-P compared to INF mothers (P < .0001). There was a significant positive correlation between maternal and neonatal serum anti-S IgG after vaccination (r = 0.68, P = .013), but not infection. CONCLUSIONS: BNT161b2 vaccination in late pregnancy or lactation enhances systemic immunity through serum anti-S immunoglobulin, while SARS-CoV-2 infection induces mucosal over systemic immunity more efficiently through BM immunoglobulin production. Next-generation vaccines boosting mucosal immunity could provide additional protection to the mother-infant dyad. Future studies should focus on identifying the optimal timing of primary and/or booster maternal vaccination for maximal benefit.

Proteomic Analysis of Human Milk Reveals Nutritional and Immune Benefits in the Colostrum from Mothers with COVID-19.

Despite the well-known benefits of breastfeeding and the World Health Organization's breastfeeding recommendations for COVID-19 infected mothers, whether these mothers should be encouraged to breastfeed is under debate due to concern about the risk of virus transmission and lack of evidence of breastmilk's protective effects against the virus. Here, we provide a molecular basis for the breastfeeding recommendation through mass spectrometry (MS)-based proteomics and glycosylation analysis of immune-related proteins in both colostrum and mature breastmilk collected from COVID-19 patients and healthy donors. The total protein amounts in the COVID-19 colostrum group were significantly higher than in the control group. While casein proteins in COVID-19 colostrum exhibited significantly lower abundances, immune-related proteins, especially whey proteins with antiviral properties against SARS-CoV-2, were upregulated. These proteins were detected with unique site-specific glycan structures and improved glycosylation diversity that are beneficial for recognizing epitopes and blocking viral entry. Such adaptive differences in milk from COVID-19 mothers tended to fade in mature milk from the same mothers one month postpartum. These results suggest that feeding infants colostrum from COVID-19 mothers confers both nutritional and immune benefits, and provide molecular-level insights that aid breastmilk feeding decisions in cases of active infection.

Serum and breastmilk SARS-CoV-2 specific antibodies following BNT162b2 vaccine: prolonged protection from SARS-CoV-2 in newborns and older children.

OBJECTIVES: Vaccination is the best strategy against COVID-19. We aimed to determine antibodies against SARS-CoV-2 in breastmilk and serum of mothers vaccinated with the mRNA vaccine. METHODS: This prospective study included 18 lactating women vaccinated with the BNT162b2 vaccine. Serum and breastmilk were collected before the first dose (T0), at the second dose (T1), 3 weeks after the second dose (T2), and 6 months after the first dose (T3). Serum anti-SARS-CoV-2 Spike (S) Immunoglobulin G (IgG) and Immunoglobulin A (IgA) were measured using a semi-quantitative enzyme-linked immunosorbent assay (ELISA) and secretory antibody (s) IgG and IgA in breastmilk using quantitative analysis. RESULTS: We detected serum anti-S IgG and IgA in all women after vaccination. Specific IgG and IgA were higher at T1, T2, and T3 compared with T0 (P <0.0001). Higher antibody levels were observed at T2 and lower values at T3 versus T2 (P = 0.007). After 6 months, all patients had serum IgG, but three of 18 (16%) had serum IgA. In breastmilk, sIgA was present at T1 and T2 and decreased after 6 months at T3 (P = 0.002). Breastmilk sIgG levels increased at T1 and T2 and peaked at T3 (P = 0.008). CONCLUSION: Secretory antibodies were transmitted through breastmilk until 6 months after anti-COVID-19 mRNA vaccination. Protection of the newborn through breastfeeding needs to be addressed.

Breastfeeding and humanitarian emergencies: the experiences of pregnant and lactating women during the earthquake in Abruzzo, Italy.

BACKGROUND: Emergencies have a great impact on infant and young child feeding. Despite the evidence, the recommended feeding practices are often not implemented in the emergency response, undermining infant and maternal health. The aim of this study was to explore the experiences of pregnant and lactating women during the earthquake emergency that occurred in L'Aquila on 6 April 2009. METHODS: The study design was qualitative descriptive. Data were collected by individual semi-structured interviews, investigating the mother's experiences of pregnancy, childbirth, breastfeeding, infant formula or complementary feeding during the emergency and the post emergency phase. Data analysis was categorical and was performed by using N-Vivo software. RESULTS: Six women who were pregnant at the time of the earthquake were interviewed in January 2010. In addition to the essential needs of pregnant and lactating women, such as those related to the emergency shelters conditions, the main findings emerged from this study were: the reconfiguration of relationships and the central role of partners and family support; the need of spaces for sharing experiences and practices with other mothers; the lack of breastfeeding support after the hospital discharge; the inappropriate donations and distribution of Breast Milk Substitutes. CONCLUSIONS: During and after L'Aquila earthquake, several aspects of infant and young child feeding did not comply with standard practices and recommendations. The response system appeared not always able to address the specific needs of pregnant and lactating women. It is urgent to develop management plans, policies and procedures and provide communication, sensitization, and training on infant and young child feeding at all levels and sectors of the emergency response.

SARS-CoV-2 infection and neonates: Evidence-based data after 18 months of the pandemic.

After 18 months of the COVID-19 pandemic, data concerning SARS-CoV-2 infection in pregnant women and their neonates are progressively taking the place of complete uncertainty. Here, we summarize updated evidence regarding several critical aspects of perinatal SARS-CoV-2 infection, including 1) vertical transmission of the virus in utero, which is possible but seems rare according to current epidemiological data; 2) how COVID-19 during pregnancy can shape maternal and neonatal outcomes, either directly or indirectly; 3) how recommendations regarding the management of infected dyads have been progressively modified in light of new scientific evidence; and 4) how maternal infection or vaccination can induce the passive protection of fetuses and neonates against the infection, through the transfer of specific antibodies before and after birth.

Adverse Effects of Infant Formula Made with Corn-Syrup Solids on the Development of Eating Behaviors in Hispanic Children.

Few studies have investigated the influence of infant formulas made with added corn-syrup solids on the development of child eating behaviors. We examined associations of breastmilk (BM), traditional formula (TF), and formula containing corn-syrup solids (CSSF) with changes in eating behaviors over a period of 2 years. Feeding type was assessed at 6 months in 115 mother-infant pairs. Eating behaviors were assessed at 12, 18 and 24 months. Repeated Measures ANCOVA was used to determine changes in eating behaviors over time as a function of feeding type. Food fussiness and enjoyment of food differed between the feeding groups (p < 0.05) and changed over time for CSSF and TF (p < 0.01). Food fussiness increased from 12 to 18 and 12 to 24 months for CSSF and from 12 to 24 months for TF (p < 0.01), while it remained stable for BM. Enjoyment of food decreased from 12 to 24 months for CSSF (p < 0.01), while it remained stable for TF and BM. There was an interaction between feeding type and time for food fussiness and enjoyment of food (p < 0.01). Our findings suggest that Hispanic infants consuming CSSF may develop greater food fussiness and reduced enjoyment of food in the first 2 years of life compared to BM-fed infants.

Evaluation of a breastmilk hand expression toolkit: the M.I.L.K survey study.

BACKGROUND: Breastmilk hand expression (BMHE) is recommended to promote lactation, relieve breast engorgement, and collect milk for future infant feedings. Resources to teach this skill are limited and infrequently developed in partnership with the obstetrical population. In collaboration with maternity care experts and individuals with recent breastfeeding experience, we designed a one-page toolkit that describes the process of BMHE and includes step-by-step instructions and images to illustrate the technique. This study aimed to evaluate the readability, clarity of content, layout, and informational value of this BMHE toolkit. METHODS: Individuals who intended to breastfeed, were currently breastfeeding, or had recently breastfed were electronically surveyed and completed a two-part survey that consisted of radio, multi-select, Likert scale, and open-ended questions. Part one captured sociodemographic factors, obstetrical history, and breastfeeding practices. Part two collected feedback on the BMHE toolkit. Participants were recruited electronically through social media and posters were circulated in antenatal and postnatal care settings in Ottawa, Canada between November 2020 and February 2021. RESULTS: Of the 123 participants, 117 (95.1%) had heard of hand expression prior to reviewing the toolkit and 99 (80.5%) had hand expressed before. Among the 48 participants who were no longer exclusively breastfeeding at the time of the survey, 22 (45.8%) had exclusively breastfed their infant for at least six months and 7 (14.6%) had discontinued exclusive breastfeeding within the first month. When asked about the BMHE toolkit, 118 (95.9%) participants said it was informative, 115 (93.5%) said it was easy to understand, and 114 (92.7%) said it was well laid-out. When asked about information seeking behaviours, participants indicated a preference for online resources (58.5%) and video resources (22.0%). CONCLUSIONS: The BMHE toolkit was well received by participants and the feedback was favourable overall. The survey feedback will be used to create a revised version of the toolkit that has been validated by the obstetrical patient population. Future research should focus on identifying implementation strategies to optimize the use of the toolkit and increase its effectiveness as an educational resource to teach participants correctly BMHE.

Infant and young child feeding during natural disasters: A systematic integrative literature review.

BACKGROUND: As climate change worsens, the frequency and intensity of natural disasters continues to increase. These extreme weather events particularly affect the physical and mental health of vulnerable groups such as mothers and infants. From low-income to high income countries, poorly organised disaster response can negatively impact infant and young child feeding practices. AIM: To examine challenges and supportive strategies for infant and young child feeding during natural disasters to inform further research and guide disaster recommendations and practice. METHODS: A comprehensive search strategy explored the electronic databases PubMed, CINAHL and Cochrane Library. Screening, data extraction and analysis were conducted using Covidence. Quality assessment was conducted using the Mixed Methods Appraisal Tool (MMAT). Studies were analysed using thematic analysis. FINDINGS: This review included 13 studies (4 mixed methods, 1 critical ethnography, 2 quasi-experimental studies, 4 descriptive studies, 1 qualitative study, 1 evidence gap map analysis). Breastfeeding facilitators during natural disaster contexts are privacy for breastfeeding, community and family support, adaptation of professional breastfeeding support to the local context and pre-existing breastfeeding practice. Breastfeeding challenges during natural disasters include decreased breastfeeding self-efficacy, lack of knowledge and resources and over-reliance on formula baby milks. Formula baby milk feeding challenges during natural disasters are the lack of access to resources required for hygienic formula baby milk preparation as well as the lack of availability of formula baby milk in some contexts. CONCLUSION: This systematic integrative review demonstrates that interventions which facilitate optimal infant and young child feeding in natural disaster contexts must be culturally and socially appropriate; increasing women's knowledge of optimal breastfeeding and safe formula baby milk feeding practices as well as breastfeeding self-efficacy.

Breastmilk as a Multisensory Intervention for Relieving Pain during Newborn Screening Procedures: A Randomized Control Trial.

The study aim was to explore the effects of multisensory breastmilk interventions on short-term pain of infants during newborn screening. This is a randomized controlled trial. A total of 120 newborns were recruited and assigned by randomization to one of three treatment conditions: Condition 1 = routine care (gentle touch + verbal comfort); Condition 2 = breastmilk odor + routine care; or Condition 3 = breastmilk odor + taste + routine care. Pain was scored with the Neonatal Infant Pain Scale (NIPS). Data were collected from video recordings at 1 min intervals over the 11 phases of heel sticks: phase 1, 5 min before heel stick without stimuli (baseline); phase 2 to phase 6 (during heel stick); and phase 7 to phase 11 (recovery). Generalized estimating equations compared differences in pain scores for newborns over phases among the three conditions. Compared with the routine care, provision of the odor and taste of breastmilk reduce NIPS scores during heel sticks (B = -4.36, SE = 0.45, p < 0.001 [phase6]), and during recovery (B = -3.29, SE = 0.42, p < 0.001 [phase7]). Our findings provide new data, which supports the use of multisensory interventions that include breastmilk odor and taste in combination with gentle touch and verbal comfort to relieve pain in infants undergoing newborn screening.

Comparison of SARS-CoV-2-Specific Antibodies in Human Milk after mRNA-Based COVID-19 Vaccination and Infection.

SARS-CoV-2-specific antibodies are secreted into human milk of infected or vaccinated lactating women and might provide protection to the breastfed infant against COVID-19. Differences in antibody response after these types of exposure are unknown. In this longitudinal cohort study, we compared the antibody response in human milk following SARS-CoV-2 vaccination or infection. We analyzed 448 human milk samples of 28 lactating women vaccinated with the SARS-CoV-2 vaccine BNT162b2 as well as 82 human milk samples of 18 lactating women with a prior SARS-CoV-2 infection. The levels of SARS-CoV-2-specific IgA in human milk were determined over a period of 70 days both after vaccination and infection. The amount of SARS-CoV-2-specific IgA in human milk was similar after SARS-CoV-2 vaccination and infection. After infection, the variability in IgA levels was higher than after vaccination. Two participants with detectable IgA prior to vaccination were analyzed separately and showed higher IgA levels following vaccination compared to both groups. In conclusion, breastfed infants of mothers who have been vaccinated with the BNT162b2 vaccine receive human milk with similar amounts of SARS-CoV-2-specific antibodies compared to infants of previously infected mothers.

Secretory IgA and T cells targeting SARS-CoV-2 spike protein are transferred to the breastmilk upon mRNA vaccination.

In view of the scarcity of data to guide decision making, we evaluated how BNT162b2 and mRNA-1273 vaccines affect the immune response in lactating women and the protective profile of breastmilk. Compared with controls, lactating women had a higher frequency of circulating RBD memory B cells and higher anti-RBD antibody titers but similar neutralizing capacity. We show that upon vaccination, immune transfer to breastmilk occurs through a combination of anti-spike secretory IgA (SIgA) antibodies and spike-reactive T cells. Although we found that the concentration of anti-spike IgA in breastmilk might not be sufficient to directly neutralize SARS-CoV-2, our data suggest that cumulative transfer of IgA might provide the infant with effective neutralization capacity. Our findings put forward the possibility that breastmilk might convey both immediate (through anti-spike SIgA) and long-lived (via spike-reactive T cells) immune protection to the infant. Further studies are needed to address this possibility and to determine the functional profile of spike T cells.