COVID-19 mRNA vaccine and antibody response in lactating women: a prospective cohort study.

BACKGROUND: Immunological protection via breastfeeding is well known. The immunological profile of human milk changes during lactation. No clinical trials have been conducted in lactating women with the newest mRNA vaccines against SARS- CoV-2. A Few studies have shown the presence of antibodies in breastmilk after vaccination. The aim of this work is to study possible antibodies transfer via breastmilk and also the immunological characteristics of lactating women compared to non-lactating women, after using the BNT162b2 Pfizer vaccine. METHODS: This is a prospective cohort study with a convenience homogenous sample of 24 healthcare workers (14 lactating and 10 non-lactating women) enrolled at the time of COVID-19 vaccination. Clinical data was registered in a questionnaire. Titers of SARS-CoV-2 spike IgG, IgA and IgM were quantified in post vaccination blood and human milk. Antibody quantification was performed by an in-house ELISA to SARS-CoV-2 trimeric spike protein. RESULTS: All women showed immunity after vaccination with positive antibodies for IgM, IgA and IgG antibodies. The dominant serum antibody response was IgG. Modest levels of antibodies in breastmilk of lactating mothers were observed in this study, especially IgG in 42.9%. There was a moderate association between higher titers of IgG and a longer duration of breastfeeding (R= 0.55, p=0.041). CONCLUSIONS: Evidence of antibody transfer in human milk after COVID-19 vaccination is scarce. The presence of antibodies in human milk is reported, but immunization through breastfeeding is still to be established.

One Year of COVID-19 in Pregnancy: A National Wide Collaborative Study.

INTRODUCTION: Even though the risk of COVID-19 in pregnancy may be increased, large-scale studies are needed to better understand the impact of the infection in this population. The aim of this study is to describe obstetric complications and the rate of vertical transmission in pregnant women with SARS-CoV-2 infection. MATERIAL AND METHODS: Detected cases of SARS-CoV-2 infection in pregnancy were registered in Portuguese hospitals by obstetricians. Epidemiological, pregnancy and childbirth data were collected. RESULTS: There were 630 positive cases in 23 Portuguese maternity hospitals, most at term (87.9%) and asymptomatic (62.9%). The most frequent maternal comorbidity was obesity. The rates of preterm birth and small-to-gestational-age were 12.1% and 9.9%, respectively. In the third trimester, 2.9% of pregnant women required respiratory support. There were eight cases (1.5%) of fetal death, including two cases of vertical transmission. There were five cases of postpartum respiratory degradation, but no maternal deaths were recorded. The caesarean section rate was higher in the first than in the second wave (68.5% vs 31.5%). RT-PCR SARS-CoV-2 positivity among newborns was 1.3%. CONCLUSION: SARS-Cov-2 infection in pregnancy may carry increased risks for both pregnant women and the fetuses. Individualized surveillance and the prophylaxis of this population with vaccination. is recommended in these cases.

Introdução: Apesar do risco da COVID-19 na gravidez poder ser acrescido, são necessários estudos em larga escala para o melhor conhecimento do impacto desta infeção nesta população. O objetivo deste estudo é descrever as complicações obstétricas e a taxa de transmissão vertical em grávidas com infeção a SARS-CoV-2. Material e Métodos: Os casos conhecidos de infeção por SARS-CoV-2 na gravidez foram registados nos hospitais portugueses por obstetras. Foram recolhidos dados epidemiológicos, da gravidez e do parto. Resultados: Registaram-se 630 casos positivos em 23 maternidades portuguesas, a maioria no termo (87,9%) e assintomática (62,9%). A comorbilidade materna mais frequente foi a obesidade. A taxa de parto pré-termo e de leves para a idade gestacional foi de 12,1% e 9,9%, respectivamente. No terceiro trimestre, 2,9% das grávidas necessitaram de suporte respiratório. Verificou-se uma taxa de 1,5% de morte fetal, incluindo dois casos de transmissão vertical. Houve cinco casos de degradação respiratória no pós-parto, mas sem mortes maternas registadas. A taxa de cesarianas foi mais elevada na primeira do que na segunda vaga (68,5% vs 31,5%). A positividade do RT-PCR SARS-CoV-2 entre os recém-nascidos foi de 1,3%. Conclusão: A infeção pelo SARS-Cov-2 na gravidez pode acarretar riscos aumentados para as grávidas e fetos. Recomenda-se uma vigilância individualizada nestes casos e a profilaxia desta população com a vacinação.

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.