Breastfeeding Women’s Attitudes Towards And Acceptance And Rejection Of COVID-19 Vaccination: Implementation Research

abstract 

Objective: There is little data on lactating women’s concerns about receiving COVID-19 vaccination during breastfeeding. This research investigated breastfeeding women’s attitudes towards and acceptance or rejection of vaccination. Materials and methods: This prospective, descriptive, implementation study was conducted in the postpartum ward of Siriraj Hospital, Bangkok, Thailand. In Phase I, 40 breastfeeding women in the postpartum ward at Siriraj Hospital who were willing to participate in the study were interviewed. Phase II comprised questionnaire development and data validation. The combined multiple choice and scaling questionnaires designed based on the results from comprehensive interviews of phase I were used in the study. The questionnaire was administered to 400 participants in Phase III. Main outcome measures: Breastfeeding women’s attitudes towards and acceptance and rejection of COVID-19 vaccination. 

cistanche benefits for men-strengthen immune system

Results: The vast majority of participants (372/400 [93.0 %]) were vaccinated predelivery. Most of the subgroup of women rejecting vaccination while breastfeeding were unsure whether too frequent vaccination would harm their unborn child (52/99 [52.5 %]; crude odds ratio [cOR], 6.50; 95 % CI, 1.47–28.68; P < 0.001). The level of immunity to the COVID-19 virus did not influence their vaccination decisions (19/99 [19.2 %]; cOR, 2.38; 95 % CI, 1.26–4.47; P < 0.001). Multivariable analysis found a significant association for women agreeing with the proposition that vaccination during pregnancy should not be performed (adjusted odds ratio [aOR], 4.83; 95 % CI, 1.41–16.57; P = 0.043). Most women who rejected vaccination knew its benefits (aOR, 31.84; 95 % CI, 7.16–141.65; P < 0.001). Conclusions: Breastfeeding women generally believe that vaccines reduce infection and disease severity. The women’s COVID-19 immunity levels did not affect their acceptance or rejection of vaccination. Some mothers rejected vaccination because of concerns about possible harm to them or their newborns.

1. Introduction 

In March 2020, the World Health Organization declared the novel coronavirus (COVID-19) outbreak a global pandemic [1]. Caused by the virus SARS-CoV-2, COVID-19 infection has clinical flu-like symptoms. Some patients may develop acute respiratory distress syndrome and pneumonia. Other systemic symptoms may be present, such as dermatological manifestations and disorders of the gastrointestinal, nervous, cardiovascular, and kidney systems [2]. Lactating women are a high-risk group for COVID-19. In the postpartum period, many ongoing physiological changes occur in response to lactation. One consequence is that mothers becoming infected with SARS-CoV-2 in this period have more severe symptoms than the general population. [3] There was a limitation of the study for how lactating women are more at risk of COVID-19 infection.

In many countries worldwide, COVID-19 vaccines play a vital role. The vaccines are classified by their technological platforms into whole-virus, subunit, viral-vector, and gene (mRNA and DNA) vaccines [4,5]. Numerous campaigns have been conducted to ensure that COVID-19 vaccinations are provided to at-risk population groups. Typically, these groups are deemed to be medical personnel; people with congenital diseases, diabetes mellitus, coronary heart disease, hypertension, or obesity; and pregnant and lactating women. The vaccine hesitation rate among pregnant and breastfeeding women was 48.4 % (95 % CI = 43.4–53.4 %).[6] There was strong resistance to vaccination among some lactating mothers in 2020 [5,7]. In 2021, the Centers for Disease Control and Prevention [8], the European Medicines Agency [9], and the Royal College of Obstetricians and Gynecologists recommended COVID-19 vaccination for breastfeeding women [5,7,8]. Vaccinating lactating women against COVID-19 remains a priority policy task. The COVID-19 vaccines currently used for lactating mothers are nonreplicating viral vector vaccines. Many institutions have confirmed the safety of these particular vaccines in the general population, and in theory, they present no risks to lactating mothers or their newborns [10–12]. Nevertheless, there are limited data on the immunity of lactating women after vaccination. Regarding women who are breastfeeding, there is currently limited data on their immunity levels after vaccination, vaccine side effects, and vaccine uptake rates during the postpartum period. This lack of data has contributed to concerns among women who are breastfeeding about the safety of COVID-19 vaccination. The Centers for Disease Control and Prevention (CDC) has created the V-safe COVID-19 Vaccine Pregnancy Registry for monitoring potential safety issues. The objective of the V-safe registry is to collect data on adverse outcomes such as miscarriage, stillbirth, and pregnancy complications. CDC’s preliminary findings present that mRNA COVID-19 vaccines administered during pregnancy are safe. However, more data are needed to inform clinical and policy decisions. [13]. However, COVID-19 continues to spread, and health authorities still see vaccination as highly beneficial. This research explored breastfeeding women’s attitudes towards and acceptance and rejection of COVID-19 vaccination. The outcomes will be relevant to national policymakers setting guidelines for the education of pregnant women and breastfeeding mothers and the planning of vaccinations for these women.

cistanche tubulosa-improve immune system

Click here to view  Cistanche Enhance Immunity products

【Ask for more】 Email:cindy.xue@wecistanche.com /  Whats App:  0086 18599088692 /  Wechat:  18599088692

2. Materials and methods 

The Ethics Committee of the Siriraj Institutional Review Board approved the protocol of this prospective, descriptive, implementation study (Si1018/2021). The work was registered at the Thai Clinical Trials Registry (TCTR20211126006). This prospective, descriptive, implementation study was conducted in the postpartum ward of Siriraj Hospital, Bangkok, Thailand, during January and April 2022. This study drew upon questionnaires. Based on a proportion of results of interest of 50 % (P = 0.5), an estimation error of 5 %, and a 95 % confidence level (type I error = 0.05; 2-sided), 385 breastfeeding mothers were calculated as needed for our survey. The investigation had 3 phases.

2.1. Phase I: Comprehensive interviews

Data on the following 4 areas were collected: 

 Breastfeeding mothers’ demographic and clinical profiles. 

 Knowledge of the mothers of COVID-19 complications that may occur while breastfeeding and their attitudes towards COVID-19 vaccination. 

 Factors influencing mothers’ acceptance or rejection of COVID-19 vaccines while breastfeeding.

 Frustrations associated with mothers’ vaccination decision-making We approached breastfeeding mothers in the postpartum ward of Siriraj Hospital, with newborns of any gestational age, to seek their agreement to participate in this research phase. To this end, the mothers were individually invited to a counseling room where the project was described. The mothers were encouraged to ask questions and were informed that they were free to withdraw at any stage if they agreed to participate. They were then given time to decide if they would enroll in the trial. In all, 40 mothers volunteered as research subjects. These women were enrolled and participated only in phase I.

Informed written consent and permission for the remainder of the session to be audio recorded were obtained from each mother. A questionnaire was then completed. It explored the mothers’ knowledge of possible COVID-19 complications while breastfeeding, attitudes towards COVID-19 vaccination, and acceptance or rejection of COVID-19 vaccines while breastfeeding. This was followed by a structured interview that investigated several aspects in depth. One aspect explored was the factors influencing a decision to have or decline COVID-19 vaccination while breastfeeding. Another aspect was any frustrations previously experienced by the mothers when deciding whether to be vaccinated while breastfeeding. In all, the questionnaire and interview took approximately 30 min. Verification of the questions to ensure data integrity was subsequently undertaken.

2.2. Phase II: Questionnaire refinement and validation

The Phase I quantitative data from the questionnaire and in-depth interviews were analyzed to ascertain their means and standard deviations. These calculations allowed refinements to be made to the written and structured interview questions. The modified questions were combined into a single written questionnaire for participant use and then tested to confirm their validity and reliability. The method for questionnaire reliability was test–retest reliability by giving the questionnaire to the same group of respondents at one month after revision. The questionnaire validity was checked by the statistician who was an expert on questionnaire construction and examined for double, confusing, and leading questions.

2.3. Phase III: Questionnaire administration

Different groups of breastfeeding women were asked about the convenience of responding to the questionnaires. They can refuse to complete the questionnaire if they feel uncomfortable or embarrassed to answer them. They still received the standard care following the guidelines of post-partum care at Siriraj Hospital. Throughout the period of questionnaire retrieving, about 10 % of people refused to participate in the study. The willing volunteers will be recruited until they complete a total of 400 cases. Four hundred patients in the postpartum ward completed the revised, validated questionnaire.

cistanche tubulosa-improve immune system

2.4. Statistical analysis

For demographic data, descriptive statistics were used. Categorical data are summarised as numbers (percentages). Analyses were conducted with version 18 of PASW Statistics for Windows (SPSS Inc, Chicago, IL, USA).

3. Results

The average age of the participants was 30.9 [15–43] years, with the vast majority being Buddhist (387 cases [96.7 %]) and married (387 cases [96.7 %]). Just over half the participants were educated to a bachelor’s degree level or higher (211 cases [52.8 %]), and almost half (162 cases [40.5 %]) earned between 15,000 and 30,000 Baht/month. Most people received social security benefits (226 cases [56.5 %]). The majority received a COVID-19 vaccination before delivery (372 cases [93.0 %]), with approximately half receiving 2 vaccine doses (189 cases [47.2 %]; Table 1). A third of the respondents (36 cases [36.0 %]) contracted COVID-19 before their pregnancy (Table 1).

Approximately 50 % of the respondents agreed that COVID-19 is a potentially dangerous disease and indicated that if they learned of a way to reduce the risk of infection while breastfeeding, they would seek it immediately. However, over 50.0 % were unsure about the safety of COVID-19 vaccines: they thought the vaccines might harm them or their newborns and increase the risk of neonatal death (Fig. 1). Over half of the women expressed concern about the type and the number of vaccinations needed, and 47.8 % preferred to be able to select the type of vaccine that would be administered. Approximately 50 % of the respondents indicated that social media had influenced their vaccination decisions. Two-thirds (63.5 %) were unsure whether vaccines given during breastfeeding would increase the immunity of their newborn. Slightly more than half of the mothers thought that overly frequent vaccinations might harm them (54.0 %) or their newborns (57.8 %). Nearly two thirds of the women (60.8 %) opined that knowing their level of immunity to COVID-19 would affect their decision to be vaccinated while breastfeeding (Fig. 1).

Of the mothers who accepted the proposition of having a COVID-19 vaccination while breastfeeding, 60.8 % indicated that they were unsure about its safety, expressing concern that the vaccines might harm their newborn child. In addition, 51.8 % of the mothers stated that they would need to consult others before deciding whether to get vaccinated (Fig. 2). For the mothers who rejected the proposition of having a COVID-19 vaccination while breastfeeding, 47.5 % were unsure that the vaccines could prevent infection in breastfeeding women. Moreover, 52.5 % reported being concerned that the vaccines might cause disabilities or abnormalities in their newborns (Fig. 2).

Table 1 Demographic data of breastfeeding women who responded to the questionnaire.

More than 70 % of the breastfeeding women indicated that the core factors influencing their vaccination decisions were the following: 

 the severity of COVID-19 illness 

 the reduction in infection and disease severity resulting from vaccination and the potential harm to newborns caused by COVID-19 vaccines (Table 2).

From our study, 93 % of lactating women had been vaccinated at least 1 dose before delivery. (Table 1) About 40 % of them still hesitated or refused injection because they were concerned about the safety of the newborns and wanted to know the immunity level after the previous vaccination. (Table 2). More than 60 % of the women reported that being required to have vaccination certification greatly influenced their work and daily life (65.0 %). Approximately two thirds (63.3 %) stated that social media information about the dangers of vaccination or the death of pregnant women influenced their vaccination decisions. Additionally, more than 70 % of the women reported that their vaccination decisions were affected by the type and number of vaccinations and their levels of COVID-19 immunity (Fig. 3).

Of the 99 women who rejected COVID-19 vaccination for various reasons, over two-thirds were educated with less than a bachelor’s degree (71/99 [71.7 %]; crude odds ratio [cOR], 3.93; 95 % CI, 2.40–6.45; P < 0.001). Half of the 99 women rejecting vaccination held the view that women should not be vaccinated against COVID-19 infection if they are breastfeeding (50/99 [50.5 %];] cOR, 4.62; 95 % CI, 2.18–9.78; P < 0.001). (Table 3). Most mothers were unsure about the safety of the vaccines. They expressed concern about whether the vaccines could harm them (65/99 [65.7 %]; cOR, 4.31; 95 % CI, 2.37–7.81; P < 0.001) or their newborns (56/99 [56.6 %]; cOR, 2.85; 95 % CI, 1.35–6.04; P < 0.001). Some mothers were also fearful that the vaccines might cause the death of their newborns (51/99 [51.5 %]; cOR, 1.98; 95 % CI, 1.02–3.84; P < 0.001; Table 3). Over half of the women believed that they should not be vaccinated while breastfeeding (59/99 [59.6 %]; cOR, 15.30; 95 % CI, 5.31–44.05; P < 0.001). They expressed apprehension that having too many vaccinations might harm them (65/991 [65.7 %]; cOR, 4.31; 95 % CI, 2.37–7.81; P < 0.001) or their newborns (56/99 [56.6 %]; cOR, 2.85; 95 % CI, 1.35–6.04; P < 0.001) or risked the death of their newborns (51/99 [51.5 %]; cOR, 1.98; 95 % CI, 1.02–3.84; P < 0.001; Table 3). Most of the lactating women decided to reject being vaccinated against COVID-19 while breastfeeding. This was despite their awareness of the benefits of vaccines (adjusted odds ratio [aOR], 31.84; 95 % CI, 7.16–141.65; P = 0.001; Table 4).

Fig. 1. Patient attitudes towards COVID-19 infection and vaccination

Fig. 2. The acceptance and rejection of COVID-19 vaccination, and knowledge of infection complications during breastfeeding.

Table 2 Information used to decide about having COVID-19 vaccination (can select more than one choice)

Fig. 3. Grievances about the decision to get vaccinated

4. Discussion 

The situation with the COVID-19 pandemic has improved dramatically now that most people have been vaccinated against infection. Nevertheless, there is still no global health policy recommendation that newborns should be given COVID-19 vaccinations, and lactating women are a group of concern. It has been reported that most lactating women prefer to delay vaccination until they have stopped breastfeeding, which may be up to 2 years or longer after their child’s birth [14].

Our research determined that a substantial majority of the lactating women (93 %) had been vaccinated, nearly half (47.2 %) had received at least 2 doses, and a third (36 %) had been infected with COVID-19 before delivery. The mothers realized they had a high risk of developing severe illness from COVID-19 while lactating. However, they were still hesitant about getting vaccinated because of concerns about whether the vaccines would present dangers to them or their newborns. Most of the mothers vaccinated before delivery were also apprehensive about the perceived high number of vaccinations and the type of vaccine that would be used. The mothers accepting the proposition of having a COVID-19 vaccination while breastfeeding were convinced that the vaccine would boost their newborns’ immunity via breast milk.

Newborns have an immature immune system. During their first few years, they have a degree of immunity through various antibodies that were passed on to them through the placenta before birth and breast milk after birth. However, the mechanism of transmission of antibodies that prevent COVID-19 infection via breast milk is unclear (15). If a mother is vaccinated against COVID-19 during the prenatal period, their babies may gain COVID-19 immunity through the placenta and milk. While it is known that immunoglobulin G (IgG) can be passed through the placenta, it is not yet clear whether milk-transmitted IgG can protect infants from infection with COVID-19 (15). Therefore, the immune response of breastfeeding women following COVID-19 vaccination may differ from the general population (women who are not breastfeeding).

cistanche benefits for men-strengthen immune system

Some studies found significant secretion of SARS-CoV-2-specific IgA in human milk and plasma after SARS-CoV-2 vaccination and getting SARS-CoV-2 infection without the evidence of duration of this immune response. [16,17] The prevalence of IgA which is passive immunity in breast milk can affect the capacity to neutralize the COVID-19 virus in breastfeeding infants. [16,17]. Research on COVID-19 vaccination of breastfeeding women has examined the transmission of immunity to babies via breast milk and the immune effects of various amounts of breast milk. It was found that COVID-19 vaccination produced similar side effects in pregnant, nonpregnant, and lactating women. In particular, minimal amounts of the vaccine components and very low mRNA concentrations were found in breast milk. These findings are consequential, as low concentrations of mRNA would not be absorbed by breastfed babies’ gastrointestinal tracts [18,19].

Several studies have detected anti-SARS-CoV-2 immunoglobulin A (IgA) and IgG in breast milk for up to 8 weeks after a second COVID-19 vaccination given while breastfeeding [20,21]. Research on pertussis and influenza vaccinations given to pregnant women found serum IgA and IgG in their breast milk at levels that protected their newborns [15,22]. Data on the effects of COVID-19 vaccination on milk supply are minimal. Various studies have shown that vaccination can reduce and increase milk production, but general patterns have not yet been concluded. Only a few women reported a reduction in breast milk production after receiving a vaccination, but the reduction was temporary, with milk flow returning to normal within 1 to 3 days. Conversely, there have been some reports of increased breast milk [21,23]. In addition, a change in the color of the mother’s milk has been observed [24]. Other reported adverse reactions are drowsiness, gastrointestinal problems sleep disturbances in mothers; poor sleep in newborns; and infant rashes [25,26].

Studies on the safety and side effects of mRNA-based vaccination in breastfeeding mothers ascertained that the most common side effects are injection site pain, weakness, chills, headache, muscle and body aches, fever, and vomiting [25,26]. These side effects are identical to those found in the general population [11]. Our research revealed that the lactating women considered that the Thai government and the Thai Ministry of Health had taken insufficient action to persuade lactating women to get vaccinated.

Table 3 Univariable analysis of factors associated with COVID-19 vaccination (choose only some factors that are likely to have a relationship; P < 0.10).

Table 3 (continued)

Table 3 (continued)

Table 4 Multivariable analysis (using the forward stepwise method: multiple logistic regression of factors associated with rejected vaccination (choose only some factors that are likely to have a relationship; P < 0.10).

Inadequate vaccination promotional campaigns would result in a lack of knowledge of the critical need for vaccination among pregnant and lactating women and may contribute to their reluctance or refusal to be vaccinated while breastfeeding. Furthermore, a lack of advice from medical personnel to lactating women may be because there currently needs to be more studies on the vaccination of women who are breastfeeding. The rejection rate of COVID-19 vaccination during breastfeeding is related to scientific research about the safety of COVID-19 vaccination to increase trust and reduce the rejection rate. The Thai government should stand on the present findings which confirm the necessity of public education campaigns to improve the quality of the database on COVID-19 vaccination among breastfeeding women.

As of October 2022, 75 out of 224 countries explicitly recommend the COVID-19 vaccine for lactating women, while 93 permit breastfeeding women to receive or elect to receive the vaccine. Five countries recommend vaccination for specific groups of breastfeeding women (such as health workers or women with underlying medical conditions). Nine countries do not recommend vaccination for women who are breastfeeding. More information on the policies of the remaining 42 countries is needed [14]. Unfortunately, there is a paucity of data supporting vaccination safety during lactation. However, choosing not to breastfeed as a precautionary measure may produce undesirable physical and psychological effects on the mother and the newborn. The adverse effects would be especially apparent during the first 6 months after birth when breastfeeding is recommended by the World Health Organization [27] and the United Nations Children’s Fund [28]. Moreover, refusing vaccination in the postpartum period heightens the risk of infection and severe symptoms of COVID-19. Consequently, careful consideration should be given to the advantages and drawbacks of vaccination and the recommendation that women breastfeed during the postpartum period.

cistanche tubulosa-improve immune system

Our research found that a sizeable proportion of the mothers rejecting vaccination while breastfeeding were educated with less than a bachelor’s degree and thought that vaccination should be avoided while breastfeeding. Vigorously promoting the benefits of vaccination in protecting lactating women from the hazards of COVID-19 is imperative until conclusive data on the safety of the vaccines for lactating women and their babies are available.

5. Conclusions

Despite breastfeeding women knowing the severity of COVID-19, they tend to be skeptical about getting vaccinated while breast feeding. This attitude stems from concerns about the safety of vaccines and fears that they may be dangerous to them and their newborns. The mothers’ decisions to accept or decline vaccination while breastfeeding were not affected by their levels of immunity to COVID-19 infection.

References 

[1] World Health Organization. Who director general opening-remarks at the media briefing on Covid-19. 11 March 2020. Available at: https://www.who. int/director-general/speeches/detail/who-director-generals-opening-remarks at-the-media-briefing-on-covid-19—11-march-2020.

[2] Guan WJ, Ni ZY, Hu Y, Liang WH, Ou CQ, He JX, et al. Clinical Characteristics of Coronavirus Disease 2019 in China. N Engl J Med 2020;382(18):1708–20. 

[3] CDC. COVID-19 vaccines while pregnant or breastfeeding. Last updated January 28, 2022. accessed on 2022 Feb 11. Available from: https://www. cdc.gov/coronavirus/2019-ncov/vaccines/recommendations/pregnancy.html. 

[4] Federal government Belgium. Coronavirus COVID-19 vaccination. Available at: https://www.info-coronavirus.be/en/vaccination/. 2021. 

[5] Heinz FX, Stiasny K. Distinguishing features of current COVID-19 vaccines: knowns and unknowns of antigen presentation and modes of action. npj Vaccines 2021;6(1):104. 

[6] Bianchi FP, Stefanizzi P, Di Gioia MC, Brescia N, Lattanzio S, Tafuri S. COVID-19 vaccination hesitancy in pregnant and breastfeeding women and strategies to increase vaccination compliance: a systematic review and meta-analysis. Expert Rev Vaccines 2022;21(10):1443–54.

[7] Hare H, Womersley K. Why were breastfeeding women in the UK denied the COVID-19 vaccine? BMJ 2021;372:n4.

[8] Merewood A, Bode L, Davanzo R, Perez-Escamilla R. Breastfeeding or being vaccinated unreasonable default recommendation. Lancet 2021;397 (10274):578.

[9] European medicines agency. International cooperation align approaches regulation Covid-19 vaccines-medicines @ Www.Ema.Europa.Eu Available at: https://www.ema.europa.eu/en/news/international-cooperation alignapproaches-regulation-covid-19-vaccines-medicines. 2021.

[10] Royal College of Obstetricians & Gynaecologists. COVID-19 vaccines, pregnancy and breastfeeding @. Available at: www.rcog.org.uk. 2021. 

[11] COVID-19 Information About COVID-19 Vaccines for People Who Are Pregnant or Breastfeeding Limited Data Are Available About the Safety of COVID-19 Vaccines for People Who Are Pregnant Follow Recommendations to Prevent the Spread of COVID-19 After Vaccination. USA: CDC (2021). pp. 2019–22.; 2019. 

[12] Department of Health & Social Care UK. Joint-Committee-on vaccination and immunisation advice on priority groups for covid-19-vaccination 30 December 2020 @ Www.Gov.Uk Available at: https://www.gov.uk/government/ publications/priority-groups-for-coronavirus-covid-19-vaccination advicefrom-the-jcvi-30-december-2020/joint-committee-on-vaccination andimmunisation-advice-on-priority-groups-for-covid-19-vaccination-30- december-2020.

[13] V-safe After Vaccination Health Checker for COVID-19 Vaccine. National Center for Immunization and Respiratory Diseases (NCIRD), Division of Viral Diseases. Centers for Disease Control and Prevention. CDC 24/7: Saving lives, Protecting People. November 14, 2022. Available in: https://www. cdc.gov/coronavirus/2019-ncov/vaccines/safety/vsafe.html. 

[14] World Health Organization. COVID-19 Vaccine Policies on Lactation. Available at: https://www.comitglobal.org/explore/public-health-authorities/lactation. 2021.

[15] Atyeo C, Alter G. The multifaceted roles of breast milk antibodies. Cell 2021;184(6):1486–99. 

[16] Valcarce V, Stafford LS, Neu J, Cacho N, Parker L, Mueller M, et al. Detection of SARS-CoV-2-Specific IgA in the Human Milk of COVID-19 Vaccinated Lactating Health Care Workers. Breastfeed Med 2021;16(12):1004–9. 

[17] Fox A, Marino J, Amanat F, Oguntuyo KY, Hahn-Holbrook J, Lee B, et al. The IgA in milk induced by SARS-CoV-2 infection is comprised of mainly secretory antibody that is neutralizing and highly durable over time. PLoS One 2022;17 (3):e0249723. 

[18] Golan Y, Prahl M, Cassidy AG, Gay C, Wu AHB, Jigmeddagva U, et al. COVID-19 mRNA Vaccination in lactation: assessment of adverse events and vaccine-related antibodies in mother-infant dyads. medRxiv 2021. 

[19] Low JM, Gu Y, Ng MSF, Amin Z, Lee LY, Ng YPM, et al. Codominant IgG and IgA expression with minimal vaccine mRNA in the milk of BNT162b2 vaccinees. npj Vaccines 2021;6(1):105. 

[20] Collier AY, McMahan K, Yu J, Tostanoski LH, Aguayo R, Ansel J, et al. Immunogenicity of COVID-19 mRNA vaccines in pregnant and lactating women. JAMA 2021;325(23):2370–80.

[21] Lechosa-Muniz C, Paz-Zulueta M, Mendez-Legaza JM, Irure-Ventura J, Cuesta Gonzalez R, Calvo Montes J, et al. Induction of SARS-CoV-2-specific IgG and IgA in serum and milk with different SARS-CoV-2 vaccines in breastfeeding women: a cross-sectional study in northern Spain. Int J Environ Res Public Health 2021;18(16).

[22] Vaccination safety for breastfeeding mothers. Division of nutrition, Physical Activity, and obesity, national center for Chronic Disease Prevention and health promotion 20 Available at: https://www.cdc.gov/breastfeeding/breastfeeding specialcircumstances/vaccinations-medications-drugs/vaccinations.html. 

[23] Muyldermans J, De Weerdt L, De Brabandere L, Maertens K, Tommelein E. The Effects of COVID-19 vaccination on lactating women: a systematic review of the literature. Front Immunol 2022;13:852928.

[24] Low JM, Lee LY, Ng YPM, Zhong Y, Amin Z. Breastfeeding Mother, and Child Clinical Outcomes After COVID-19 Vaccination. J Hum Lact 2022;38(1):37–42.

[25] Golan Y, Prahl M, Cassidy AG, Gay C, Wu AHB, Jigmeddagva U, et al. COVID-19 mRNA vaccination in lactation: assessment of adverse events and vaccine-related antibodies in mother-infant dyads. Front Immunol 2021;12:777103.

[26] Bertrand K, Honerkamp-Smith G, Chambers CD. Maternal and child outcomes reported by breastfeeding women following messenger RNA COVID-19 vaccination. Breastfeed Med 2021;16(9):697–701. 

[27] World Health Organization. Infant and young child feeding. Available at: http://www.who.int/en/news-room/fact-sheets/detail/infant-and youngchild-feeding. 2021. 

[28] UNICEF. Breastfeeding And Family-Friendly Policies An Evidence Brief Breastfeeding And Family-Friendly Policies. In: An Evidence Brief M Griswold, A Palmquist. New York, USA; 2019.