BackgroundData regarding symptoms in the lactating mother-infant dyad and their immune response to COVID-19 mRNA vaccination during lactation are needed to inform vaccination guidelines.MethodsFrom a prospective cohort of 50 lactating individuals who received mRNA-based vaccines for COVID-19 (mRNA-1273 and BNT162b2), blood and milk samples were collected prior to first vaccination dose, immediately prior to 2nd dose, and 4-10 weeks after 2nd dose. Symptoms in mother and infant were assessed by detailed questionnaires. Anti-SARS-CoV-2 antibody levels in blood and milk were measured by Pylon 3D automated immunoassay and ELISA. In addition, vaccine-related PEGylated proteins in milk were measured by ELISA. Blood samples were collected from a subset of infants whose mothers received the vaccine during lactation (4-15 weeks after mothers’ 2nd dose).ResultsNo severe maternal or infant adverse events were reported in this cohort. Two mothers and two infants were diagnosed with COVID-19 during the study period before achieving full immune response. PEGylated proteins were not found at significant levels in milk after vaccination. After vaccination, levels of anti-SARS-CoV-2 IgG and IgM significantly increased in maternal plasma and there was significant transfer of anti-SARS-CoV-2-Receptor Binding Domain (anti-RBD) IgA and IgG antibodies to milk. Milk IgA levels after the 2nd dose were negatively associated with infant age. Anti-SARS-CoV-2 IgG antibodies were not detected in the plasma of infants whose mothers were vaccinated during lactation.ConclusionsCOVID-19 mRNA vaccines generate robust immune responses in plasma and milk of lactating individuals without severe adverse events reported.

Importance: Data regarding efficacy and safety of anti-COVID-19 mRNA vaccines during lactation is needed to address vaccination guidelines, ease vaccine hesitancy concerns, and inform public health strategies for this population. Objective: To determine whether anti-COVID-19 mRNA-based vaccines administered during lactation illicit an immune response or the transfer of anti-SARS-CoV2 antibodies into human milk. Design: Plasma and milk samples were collected from a prospective cohort of lactating individuals who received the mRNA-based vaccines for COVID-19 and from individuals who recovered from COVID-19 infection. Setting: Ambulatory or during postpartum hospitalization. Participants: We report results from lactating participants who received the mRNA-1273 (Moderna, n=9) or the BNT162b2 (Pfizer, n=14) vaccine or recovered from natural SARS-CoV-2 infection (n=3). Interventions and Exposures: Anti-COVID-19 mRNA vaccination (BNT-162b2 and mRNA-1273) or natural SARS-CoV-2 infection. Main Outcome(s) and Measure(s): Plasma and milk samples were collected from lactating individuals before first vaccine dose, on the day of the second dose, and 4 weeks after the second dose. Maternal plasma was evaluated for vaccine-derived IgM and IgG antibodies. Human milk was evaluated by ELISA for vaccine-induced IgA antibodies specific for SARS-CoV-2. Results: Twenty-three lactating individuals were recruited for this study. Levels of IgG and IgM were significantly increased in plasma samples on the day of the second vaccine dose (post vaccine 1), when compared to pre-vaccine samples. In addition, plasma IgG levels 4 weeks after second vaccine dose were significantly higher than plasma IgG levels pre-vaccine or on the day of the second dose. In addition, our results show transfer of anti-SARS-CoV2-Receptor Binding Domain (RBD) IgA antibodies to human milk, 3-4 weeks after each dose of the COVID-19 mRNA vaccines (BNT-162b2 and mRNA-1273). The levels of anti-SARS-CoV2-RBD IgA antibody in milk of vaccinated individuals were not significantly different from levels among participants who experienced SARS-CoV-2 infection. Conclusions and Relevance: Administration of anti-COVID-19 mRNA vaccines during lactation leads to increased anti-SARS-CoV2 IgM and IgG levels in the plasma of lactating mothers and increased anti-SARS-CoV2-RBD IgA levels in human milk. Lactating women who receive the vaccine should continue breastfeeding their infant human milk to allow continuing transfer of anti-SARS-CoV-2 IgA antibodies to the neonate. Additional studies are needed to evaluate the effect of these vaccines on lactation outcomes and infant health.

ImportanceLongitudinal data on COVID-19 messenger RNA (mRNA) vaccine reactogenicity and immunogenicity in pregnancy and for the mother-infant dyad are needed.ObjectiveTo examine COVID-19 mRNA vaccine reactogenicity and immunogenicity in pregnancy and observe longitudinal maternal and infant outcomes.Design, Setting, and ParticipantsThis prospective cohort study of pregnant individuals enrolled in the COVID-19 Vaccination in Pregnancy and Lactation study from December 1, 2020, through December 31, 2021, with follow-up through March 31, 2022, was conducted at a large academic medical center in an urban metropolitan area in California. Pregnant individuals receiving COVID-19 mRNA vaccines (mRNA-1273 [Moderna] and BNT162b2 [Pfizer-BioNTech]) were eligible. Of 81 participants enrolled, 5 were excluded after enrollment: 1 terminated pregnancy, 1 received the third vaccine dose prior to delivery, and 3 delivered prior to completing the initial vaccine series.ExposureCOVID-19 mRNA vaccination at any time during pregnancy.Main Outcomes and MeasuresThe primary outcomes were vaccine response as measured by blood Immunoglobulin G (IgG) titers after each vaccine dose and self-reported postvaccination symptoms. Patients’ IgG titers were measured in cord blood and in infant blood at intervals up to 1 year of life; IgG and IgA titers were measured in maternal milk. Clinical outcomes were collected from medical records.ResultsOf 76 pregnant individuals included in final analyses (median [IQR] maternal age, 35 [29-41] years; 51 [67.1%] White; 28 [36.8%] primigravid; 37 [48.7%] nulliparous), 42 (55.3%) received BNT162b2 and 34 (44.7%) received mRNA-1237. There were no significant differences in maternal characteristics between the 2 vaccine groups. Systemic symptoms were more common after receipt of the second vaccine dose than after the first dose (42 of 59 [71.2%] vs 26 of 59 [44.1%]; P = .007) and after mRNA-1237 than after BNT162b2 (25 of 27 [92.6%] vs 17 of 32 53.1%; P = .001). Systemic symptoms were associated with 65.6% higher median IgG titers than no symptoms after the second vaccine dose (median [IQR], 2596 [1840-4455] vs 1568 [1114-4518] RFU; P = .007); mean cord titers in individuals with local or systemic symptoms were 6.3-fold higher than in individuals without symptoms. Vaccination in all trimesters elicited a robust maternal IgG response. The IgG transfer ratio was highest among individuals vaccinated in the second trimester. Anti-SARS-CoV-2 IgG was detectable in cord blood regardless of vaccination trimester. In milk, IgG and IgA titers remained above the positive cutoff for at least 5-6 months after birth, and infants of mothers vaccinated in the second and third trimesters had positive IgG titers for at least 5 to 6 months of life. There were no vaccine-attributable adverse perinatal outcomes.Conclusions and RelevanceThe findings of this cohort study suggest that mRNA COVID-19 vaccination in pregnancy provokes a robust IgG response for the mother-infant dyad for approximately 6 months after birth. Postvaccination symptoms may indicate a more robust immune response, without adverse maternal, fetal, or neonatal outcomes.

Climate change is accelerating the intensity and frequency of wildfires globally. Understanding how wildfire smoke (WS) may lead to adverse pregnancy outcomes and alterations in placental function via biological mechanisms is critical to mitigate the harms of exposure. We aim to review the literature surrounding WS, placental biology, biological mechanisms underlying adverse pregnancy outcomes as well as interventions and strategies to avoid WS exposure in pregnancy. This review includes epidemiologic and experimental laboratory-based studies of WS, air pollution, particulate matter (PM), and other chemicals related to combustion in relation to obstetric outcomes and placental biology. We summarized the available clinical, animal, and placental studies with WS and other combustion products such as tobacco, diesel, and wood smoke. Additionally, we reviewed current recommendations for prevention of WS exposure. We found that there is limited data specific to WS; however, studies on air pollution and other combustion sources suggest a link to inflammation, oxidative stress, endocrine disruption, DNA damage, telomere shortening, epigenetic changes, as well as metabolic, vascular, and endothelial dysregulation in the maternal-fetal unit. These alterations in placental biology contribute to adverse obstetric outcomes that disproportionally affect the most vulnerable. Limiting time outdoors, wearing N95 respirator face masks and using high quality indoor air filters during wildfire events reduces exposure to related environmental exposures and may mitigate morbidities attributable to WS.

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