Vaccination Beliefs and Attitudes of Lactating People During the SARS-CoV-2 Pandemic

Abstract

Background:

Pregnant and recently pregnant people have lower vaccination rates against SARS-CoV-2 than the general population, despite increased risk of adverse outcomes from infection. Little is known about vaccine hesitancy in this population.

Research Aim:

To characterize SARS-CoV-2 and other vaccine attitudes of lactating people who accepted the SARS-CoV-2 vaccine, describing their vaccine experiences to further contextualize their beliefs.

Methods:

A prospective cross-sectional online survey design was used. We administered the survey to 100 lactating people in Pennsylvania from April to August 2021, upon enrollment into a longitudinal study investigating SARS-CoV-2 vaccine antibodies in human milk. This survey assessed SARS-CoV-2 vaccine attitudes, vaccine counseling from providers, and vaccine decision making. Associations between vaccination timing and beliefs were analyzed by Pearson chi-square.

Results:

Of 100 respondents, all received ≥ 1 SARS-CoV-2 vaccine before or shortly after enrollment, with 44% (n = 44) vaccinated in pregnancy and 56% (n = 56) while lactating. Participants reported vaccination counseling by obstetric (n = 48; 70%) and pediatric (n = 25; 36%) providers. Thirty-two percent (n = 32) received no advice on SARS-CoV-2 vaccination from healthcare providers, while 69% (n = 69) were counseled that vaccination was safe and beneficial.

While 6% (n = 6) and 5% (n = 5) reported concerns about the safety of maternal vaccines for lactating people or their infants, respectively, 12% (n = 12) and 9% (n = 9) expressed concerns about the safety of maternal SARS-CoV-2 vaccination in particular.

Conclusions:

Despite high uptake of SARS-CoV-2 vaccine among participants, safety concerns persisted, with many reporting a lack of direct counseling from providers. Future research should investigate how variability in provider counseling affects SARS-CoV-2 vaccine uptake in perinatal populations.

Key Messages

• Pregnant and recently pregnant people have lower rates of vaccination against SARS-CoV-2 than other populations, yet little is known about their vaccine beliefs.

• Respondents believed vaccines are efficacious and important regardless of SARS-CoV-2 vaccination timing. Participants vaccinated during pregnancy were more likely to be healthcare workers and report uncomplicated pregnancies.

• Participants vaccinated during pregnancy had similar vaccine attitudes to those vaccinated while lactating, with both groups expressing concerns about vaccine side effects and safety.

Background

Pregnant and lactating people are less likely to accept SARS-CoV-2 vaccination than non-pregnant people, placing them and their infants at increased risk of SARS-CoV-2 infection (Battarbee et al., 2022; Mohan et al., 2021; Razzaghi et al., 2021). As of December 2021, researchers at the United States Centers for Disease Control and Prevention (CDC, 2021a) reported that only 40% of pregnant women in the United States were vaccinated against SARS-CoV-2, compared to 74.9% of women in the general population. This is despite evidence reported by Villar et al. (2021), in a multinational study of 2,130 pregnant patients, that those infected with SARS-CoV-2 during pregnancy were more likely to develop preeclampsia/eclampsia, require intensive care unit admission, experience preterm birth, and develop serious infections, compared to women uninfected in pregnancy. Furthermore, these investigators found that the risk of maternal mortality was 22 times higher for pregnant patients with SARS-CoV-2 than those without. Vaccination disparities persist despite robust data about the safety and efficacy of mRNA and adenovirus-based vaccines for perinatal recipients over the past 1.5 years, and universal recommendations for SARS-CoV-2 vaccination during pregnancy and lactation from national health agencies, including the U.S. CDC (2021b), the American College of Obstetricians and Gynecologists (ACOG, 2021), and the Society for Maternal Fetal Medicine (SMFM, 2021).

Perinatal vaccine uptake disparities are multifactorial. The unique relationship between maternal and infant health, both in pregnancy and while breastfeeding, complicates maternal vaccination decision-making, and the exclusion of pregnant and lactating people from initial mRNA-based vaccine trials delayed rigorous, large-scale safety data in these populations (Beigi et al., 2021; Costantine et al., 2020; Modi et al., 2021). Early in the pandemic, pregnant people had not yet been identified as high-risk for SARS-CoV-2 infection, and the absence of clear recommendations about maternal immunization from national organizations contributed to confusion about vaccine prioritization for this group. Fears based in vaccine misinformation related to fertility, safety, and efficacy, may also have compromised uptake in this population (Battarbee et al., 2022; Dudley et al., 2020; Sutton et al., 2021).

Despite the increased morbidity and mortality from SARS-CoV-2 infection in pregnant and recently pregnant people, SARS-CoV-2 vaccine attitudes of lactating parents have rarely been examined in the United States. Identification of patient-centered concerns can lead to improved uptake of therapies, including vaccination (Epstein & Street, 2011; ; Shon & Wells, 2020). Thus, we sought to define the patient-oriented barriers and motivations for maternal vaccination during the SARS-CoV-2 pandemic. We aimed to characterize SARS-CoV-2 and other vaccine attitudes of lactating people who accepted the SARS-CoV-2 vaccine, describing their vaccine experiences to further contextualize their beliefs.

Methods

Research Design

A prospective cross-sectional online survey design was used. This was part of a longitudinal cohort study examining SARS-CoV-2 antibodies in human milk. We aimed to capture the vaccine beliefs and factors influencing recent vaccination decisions of participants in this unique sample who were early accepters of SARS-CoV-2 vaccines, using survey methodology to collect data within a short period of time and thus minimize changes in vaccine attitudes due to the evolving nature of the pandemic. The parent study, entitled “Natural History Study to Describe SARS-CoV2 Vaccine Antibodies in Breastmilk” was approved by the University of Pittsburgh Institutional Review Board on April 7, 2021 (STUDY21010154).

Setting and Relevant Context

The catchment area for enrollment encompassed the U.S. city of Pittsburgh, Pennsylvania and surrounding suburban areas, mainly within Allegheny County. Allegheny County is home to 1.2 million people. The county’s population is 80% white (13% Black or African American), has a median income of $62,320, and 95% of the adult population have a high school education or higher (43% have a bachelor’s degree or higher; United States Census Bureau, 2022).

As of May 2022, 72% of eligible Allegheny County residents (5 years and older) were fully vaccinated against SARS-CoV-2, with 81% partially vaccinated, and 55.6% of eligible residents (12 years and older) had received at least one booster. Comparatively, as of August 2021 (end of the survey period), 62% of eligible residents were fully vaccinated and 67% were partially vaccinated (Allegheny County Health Department [ACHD], 2022b). In 2019, 82% of mothers who had live births in Allegheny County initiated breastfeeding—slightly below the national average of 84% (CDC, 2021c; Pennsylvania Department of Health [PDoH], 2021). The Maternity Practices in Infant Nutrition and Care (mPINC) is a national survey of birthing hospitals measuring breastfeeding supportive practices. In 2020, the mPINC score for Pennsylvania was 80, equal to the contemporary U.S. national average score (CDC, 2021d).

Sample

Participants were adults 18 years or older who were lactating, vaccinated against SARS-CoV-2 or considering vaccination, and willing to donate at least one sample of their expressed milk. In the study site, pregnant people became eligible for vaccine in January 2021 and lactating people became eligible in April 2021. Participants could be vaccinated with any SARS-CoV-2 vaccine, and vaccination before enrollment was not required. Exclusion criteria included unwillingness to provide a milk sample, not lactating at enrollment, or having received intravenous immune globulin (IVIG), chemotherapy, blood transfusions, or immunosuppressive medications in the previous 6 months.

Participants were recruited through flyers at a large academic delivery hospital, an online research participant registry, and referrals by clinicians in local lactation clinics. No compensation was provided. The sample size was determined by the longitudinal parent study, in which investigators determined that a convenience sample of 100 participants was sufficient to detect differences of 30% in antibody response and demographics among groups receiving different SARS-CoV-2 vaccines, with 80% power and alpha equal to 0.05. Of 132 people screened, 101 participants enrolled in the parent study after eligibility screening, and 100 completed the vaccine attitude survey (Figure 1).

Figure 1.

Flow Diagram of Surveyed Participants.

Measurement

We used “breastfeeding” terminology in the survey development and throughout this paper as an umbrella term encompassing direct breast and provision of one’s own milk to one’s child by any means (e.g., bottle). We acknowledge that parents fed their children by many different methods and use variable terminology to describe it.

Demographics and health history

Sociodemographic data including employment status, educational attainment, race/ethnicity, and marital status were collected on a baseline demographic survey created for the parent study. Participants were also asked for health information, including history of SARS-CoV-2, influenza, and Tdap vaccinations in pregnancy, obstetric and infant health history, history of SARS-CoV-2 infection, and timing and side effects from SARS-CoV-2 vaccination.

Vaccine influences

Multiple-choice questions on an investigator-created vaccine attitudes survey assessed if healthcare professionals had provided recommendations about maternal SARS-CoV-2 vaccination, then branching logic was used to ascertain vaccine advice received. Respondents ranked the importance of various medical influences on vaccine decision making (e.g., advice from obstetric providers), on a scale of 1 to 5. Participants also ranked the importance of different social figures or groups, including family and local healthcare organizations, on their vaccine choices.

Vaccine attitudes

Vaccine attitude questions were adapted from published surveys on maternal influenza, Tdap, and pertussis vaccines (Dudley et al., 2020; Li et al., 2020; Van Buynder et al., 2019; Vulpe & Rughiniş, 2021). Twenty-eight 5-point Likert scale statements assessed: (1) general vaccine attitudes, (2) SARS-CoV-2 risk perception, and (3) SARS-CoV-2 vaccine attitudes. Attitudinal constructs assessed concerns regarding vaccine safety, efficacy, and importance, as well as vaccine acceptance in the respondent’s social circle. SARS-CoV-2 risk perception statements assessed the participant’s concern about themself and their infant contracting SARS-CoV-2. SARS-CoV-2 vaccine attitude statements explored participants’ confidence in the safety and efficacy of SARS-CoV-2 vaccines, and whether or not they felt they had adequate information and agency to make vaccination decisions.

All questions were reviewed for clarity and appropriateness by one obstetrician, two pediatricians specializing in maternal–fetal health and infectious disease, and one nursing faculty with expertise in lactation and behavioral research. To minimize question order bias, we first asked about general demographic information, then recent vaccine decision making, and finally personal vaccine attitudes. We used Likert scales for attitudinal constructs with both vaccine-acceptant and vaccine-hesitant phrasing to avoid acquiescence and desirability biases. Cronbach’s alpha coefficient was calculated for the 11-item vaccine influences subscale (α = 0.86) and the 28 vaccine attitudes subscale (α = 0.87). For the full survey, see the online Supplemental Materials.

Data Collection

The survey was administered online between April and August 2021. Interested participants were provided with a QR code or a web-link to a secure web application (REDCap) for eligibility screening. As the parent study was IRB-approved for a waiver to document informed consent, those who passed eligibility screening were asked to review the waiver and acknowledge their consent with a checkmark. Upon enrollment, consenting participants were directed to survey questions on REDCap to protect the data confidentiality.

Data Analysis

We computed descriptive statistics for all survey variables. We used binomial logistic regression to assess associations between the primary outcome variable, timing of maternal SARS-CoV-2 vaccination dichotomized as in pregnancy or lactation, and the following five dichotomized characteristics: advanced maternal age (35 years and older), multiparity, pregnancy complications (gestational hypertension, preeclampsia, gestational diabetes, and other self-reported issues), employment in healthcare, and prior SARS-CoV-2 infection or quarantine. Bonferroni correction was used for an adjusted alpha of 0.01. Any percentages reported were calculated using valid responses only, with denominators reported when response rate was less than 100%.

For the attitude and belief statements, Likert scale responses were dichotomized as vaccine acceptant or vaccine hesitant due to clustering of responses. For example, given the statement, “Vaccines can cause the disease against which they are designed to protect,” participants who answered: “strongly agree,” “agree,” or “neither agree nor disagree” were coded as vaccine hesitant, while those who answered “disagree” or “strongly disagree” were coded as vaccine acceptant. Items using reverse scoring were grouped in the opposite way, such that “strongly agree” and “agree” were coded vaccine acceptant, and other responses vaccine hesitant. Survey items with greater than 10% difference in vaccine acceptance between the two groups (vaccinated while pregnant or lactating) were selected for further analysis with Pearson chi-square tests for independence using Bonferroni correction for multiple comparisons. All analysis was performed in Stata/SE (Version 16.1).

Results

Characteristics of the Sample

Of the 100 respondents, 99 had received ≥ 1 SARS-CoV-2 vaccine before survey completion, and one received a vaccination within 2 weeks of completion. Overall, 44% (n = 44) were vaccinated in pregnancy and 56% (n = 56) were vaccinated while lactating (Table 1). Of those vaccinated while lactating, 42 delivered prior to the SARS-CoV-2 vaccine becoming available to high-risk individuals in December 2020 and would not have been able to receive vaccination in pregnancy. Most participants identified as white, married, college educated, and employed full-time, regardless of vaccine timing. Almost all reported vaccination against influenza in the 2020–2021 season (92%, n = 92) and Tdap during pregnancy (93%, n = 93).

Table 1.

Timing of Maternal SARS-Cov-2 Vaccination and Respondent Characteristics (N = 100).

Variable	Total	Vaccinated While Pregnant	Vaccinated While BF
		(n = 44)	(n = 56)
	n (%)	n (%)	n (%)
Ethnicity
White	91 (91)	43 (98)	48 (86)
Black	1 (1)	0 (0)	1 (2)
Asian	6 (6)	1 (2)	5 (9)
Other	2 (2)	0 (0)	2 (4)
Marital Status
Married	94 (94)	40 (91)	54 (96)
Domestic partner	3 (3)	3 (7)	0 (0)
Other	3 (3)	1 (2)	2 (4)
Age
Under 35 years	59 (59)	31 (70)	28 (50)
35 years and older	41 (41)	13 (30)	28 (50)
Education a
Some college	2 (2)	1 (2)	1 (2)
Undergraduate degree	36 (37)	9 (20)	27 (48)
Graduate/professional degree	62 (62)	34 (77)	28 (50)
Employment Status
Unemployed	10 (10)	3 (7)	7 (13)
Part-time employment	11 (11)	5 (11)	6 (11)
Full-time employment	73 (73)	35 (80)	38 (68)
Other	6 (6)	1 (2)	5 (9)
Employment Type
Healthcare b	42 (42)	24 (55)	18 (32)
Non-healthcare	58 (58)	20 (45)	38 (68)
Number of Children
1	42 (42)	15 (34)	27 (48)
>1	58 (58)	29 (66)	29 (52)
Pregnancy complications c
Yes	31 (33)	8 (18)	33 (59)
No	69 (68)	36 (82)	23 (41)
Flu Vaccine (2020–2021 Season) d
Yes	92 (92)	40 (91)	52 (93)
No	7 (7)	4 (9)	3 (5)
Don’t know/remember	1 (1)	0 (0)	1 (2)
Tdap Vaccine (in most recent pregnancy)
Yes	93 (93)	43 (98)	50 (89)
No	4 (4)	1 (2)	3 (5)
Don’t know/remember	3 (3)	0 (0)	3 (5)
Prior SARS-CoV-2 infection (self) e	5 (5)	1 (2)	4 (7)
Prior SARS-CoV-2 quarantine f	16 (16)	8 (18)	8 (14)
SARS-CoV-2 vaccine
Moderna	42 (43)	22 (52)	20 (36)
Pfizer	52 (53)	20 (48)	32 (57)
Johnson & Johnson/Janssen	4 (4)	0 (0)	4 (7)

Note. BF = breastfeeding. Missing data: SARS-CoV-2 vaccine type = 2.

^aUndergraduate degree includes Bachelor’s or Associate’s degree; graduate or professional degree includes Master’s degree or doctorate.

^bIncludes direct care providers (e.g. physicians, registered nurses) and other non-provider roles (e.g. Medicaid auditor).

^cComplications in most recent pregnancy, including gestational hypertension, preeclampsia, gestational diabetes, and other self-reported health issues (e.g. chorioamnionitis/preterm labor, placenta previa, uterine growth restriction).

^dOf 92 recipients of the 2020–2021 flu vaccine, 63% (n = 58) were vaccinated against flu in pregnancy, 23% (n = 21) were vaccinated in lactation, and 14% (n = 13) could not recall flu vaccine timing.

^eInfection confirmed by nose swab.

^fPrior quarantine due to known SARS-CoV-2 exposure.

SARS-CoV-2 Vaccination Experience

Forty-three percent (n = 43) received the Moderna vaccine, 53% Pfizer (n = 53), and 4% (n = 4) Johnson & Johnson/Janssen. Fifty-two percent (n = 52) experienced symptoms after the first dose of vaccine, and 65% (n = 65) after the second dose. No participants reported moderate or severe vaccine side effects. The most common side effects after any SARS-CoV-2 vaccine were sore arm (n = 72, 72%) and fatigue (n = 67, 67%); symptoms were similar between pregnant and lactating people (Figure 2).

Figure 2.

Symptoms Reported After any Maternal SARS-CoV-2 Vaccination (N = 100).

Note. Cohorts were vaccinated against SARS-CoV-2 in pregnancy (n = 44) or while lactating (n = 56). Of those vaccinated in pregnancy, one received the first SARS-CoV-2 vaccine in the first trimester, 22 in the second trimester, 13 in the third trimester, two could not recall, and six did not respond.

Motivations to Vaccinate

Ninety-six percent (n = 88/92) of respondents identified their child’s health in their top three priorities during SARS-CoV-2 vaccine decision making, with 63% (n = 58/92) naming it their most important consideration (Figure 3). Seventy-three percent (n = 65/89) ranked their own health as a top three priority, 9% of whom reported personal health as their top priority. Nearly all (n = 94/98, 96%) respondents ranked the opinions of their friends and family in their bottom three priorities when making vaccination decisions.

Figure 3.

Most and Least Important Factors to Maternal Vaccine Decision Making (N = 99).^a

Note. Prompt: “Please rate the following factors in order of importance to your decision making around getting the COVID-19 vaccine during pregnancy or while lactating/breastfeeding, 1 = least important, 6 = most important.” Responses were dichotomized into each participant’s most important priorities (ranked 4–6) and least important priorities (ranked 1–3).

^aWhile 99 participants responded to the prompt overall, some abstained from ranking certain factors, with the response rate ranging from 88–97 participants for each individual factor.

Influences on Vaccination Decision Making

Table 2 displays advice participants received about SARS-CoV-2 vaccination, as well as medical or social influences on vaccine decision making. Thirty-two percent (n = 32) received no advice from healthcare providers on SARS-CoV-2 vaccination while pregnant or breastfeeding. Obstetric and pediatric providers, including physicians, physician’s assistants, and nurse practitioners, were most frequently identified as “important” or “very important” sources of advice for SARS-CoV-2 decision making (n = 90/99, 91% and n = 84/99, 85%, respectively). Respondents most frequently identified their spouses or partners (n = 66, 67%) and federal health organizations (n = 82, 83%) as important or very important non-medical influences on vaccination decisions.

Table 2.

Advice and Influences on Vaccine Decision Making (N = 100).

Question	n (%)
1. What advice have healthcare providers given you about being vaccinated for COVID-19 while BF or lactating?
None	32 (32)
That vaccination was safe, likely safe, or could benefit me/my baby while BF	69 (69)
That it was unclear if vaccination was safe for me/my baby while BF	7 (7)
That vaccination was risky or potentially unsafe for me/my baby while BF	1 (1)
2. If given advice, which of the following healthcare providers gave you advice or information on maternal COVID-19 vaccination while BF or lactating?
PCP (primary care provider)	11 (16)
Obstetric provider (pregnancy doctor or practitioner)	48 (70)
Pediatric provider	25 (36)
Nurse	4 (6)
Other healthcare provider	11 (16)
3. If given advice, what were healthcare provider(s) final recommendation(s) to you about being vaccinated for COVID-19 while you are BF or lactating?
Vaccination as soon as possible, regardless of pregnancy/breastfeeding status	37 (54)
Vaccination because of potential benefit to infant (e.g. passive immunity through placenta/human milk)	29 (42)
No recommendation given (information only)	18 (26)
Other	5 (7)
4. People or organizations ranked “important” or “very important” to decision making around getting the COVID-19 vaccine during pregnancy or while BF
Healthcare providers
PCP (primary care provider)	54 (55)
Obstetric provider (pregnancy doctor/practitioner)	90 (91)
Postpartum nurse	43 (44)
Pediatric provider	84 (85)
Pediatric nurse	50 (51)
Other healthcare provider	34 (35)
Social influences
Spouse/partner	66 (67)
Family and friends	20 (20)
Federal or other major health organizations (e.g., WHO)	82 (83)
Local or community healthcare organizations (e.g., county health dept.)	58 (59)

Note. BF = breastfeeding, WHO = World Health Organization. Two participants reported being advised to seek vaccination during pregnancy, and three participants reported previous vaccination during pregnancy. Questions 1–3 are select-all-that-apply items. Question 4 includes 5-point Likert scale items (1 = not at all important, 2 = not important, 3 = neutral, 4 = important, 5 = very important). Missing values: Question 2 = 31; Question 3 = 31; Question 4 Healthcare providers: PCP = 2, obstetric provider = 1, postpartum nurse = 2, pediatric provider = 1, pediatric nurse = 2, other = 2; Question 4 social influences: Spouse/partner = 1, family/friends = 2, federal/major organizations = 1, local/community organizations = 1.

Vaccine Attitudes

Table 3 presents participants’ responses to attitudinal constructs on vaccination. Respondents overwhelmingly believed vaccines are carefully tested, effectively prevent infectious disease, and are important for individual and community health. Almost all expressed confidence in the safety of maternal vaccines for both lactating/breastfeeding recipient (n = 94, 94%) and their infants (n = 95, 95%). However, over half believed vaccines produce serious side effects, and 29% (n = 29) and 17% (n = 17) felt unsure or agreed that vaccines can overload the recipient’s immune system or cause diseases they are designed to prevent, respectively.

Table 3.

Vaccine Acceptant Attitudes Among Participants Vaccinated Against SARS-CoV-2 While Pregnant or Lactating (N = 100).

Statement	Total	Pregnant	Lactating
		(n = 44)	(n = 56)
	n (%)	n (%)	n (%)
General vaccine statements
• Vaccines are carefully tested before being offered to the public	96 (96)	43 (98)	53 (95)
• Vaccines can cause the disease against which they are designed to protect	83 (83)	38 (87)	45 (80)
• Vaccines can produce serious side effectsa	42 (42)	23 (52)	19 (34)
• Vaccines can overload the immune systema	71 (71)	34 (77)	37 (66)
• Vaccines are effective in preventing infectious diseases	98 (98)	43 (98)	55 (98)
• It is important for everybody to have routine vaccinations	96 (96)	43 (98)	53 (95)
• Vaccination of other people is important to protect those that cannot be vaccinated (e.g., newborn children, immunosuppressed or very sick people)	99 (99)	44 (100)	55 (98)
• I am confident that recommended maternal vaccines (vaccines approved for use in pregnant and postpartum people) are safe for breastfeeding mothers	94 (94)	43 (98)	51 (91)
• I am confident that recommended maternal vaccines (vaccines approved for use in pregnant and postpartum people) are safe for breastfeeding babies	95 (95)	44 (100)	51 (91)
• I know most of the important information needed to make a decision about getting recommended maternal vaccines (e.g., seasonal flu shot) while breastfeeding	88 (88)	42 (95)	46 (82)
COVID-19 perception statements
• I worry I could get COVID-19	83 (83)	38 (86)	45 (80)
• I worry my baby could get COVID-19 after birth	92 (92)	41 (93)	51 (91)
• COVID-19 is dangerous for people who have recently given birth	64 (64)	27 (61)	37 (64)
• COVID-19 infection is dangerous for babies	80 (80)	34 (77)	46 (82)
COVID-19 vaccine statements
• COVID-19 vaccines were rigorously tested before they were approved for use	84 (84)	40 (91)	44 (79)
• I am confident that COVID-19 vaccines are safe for breastfeeding/lactating people	88 (88)	40 (91)	48 (86)
• COVID-19 vaccines can help protect me from COVID-19 infection	96 (96)	43 (98)	53 (95)
• I am confident that COVID-19 vaccines given to breastfeeding/lactating people are safe for their breastfeeding babies	91 (91)	41 (93)	50 (89)
• If I received a COVID-19 vaccine, this could help to protect my breastfeeding baby from COVID-19 infectiona	92 (92)	44 (100)	48 (86)
• It would be better for me to develop immunity to COVID-19 by getting sick/recovering than getting vaccinated	94 (94)	42 (95)	52 (94)
• It is in my control to accept or reject COVID-19 vaccination	93 (93)	42 (95)	51 (91)
• I know enough information about the COVID-19 vaccines to decide if I want to get vaccinated while breastfeeding	93 (93)	42 (95)	51 (91)

Note. The survey assessed vaccine attitudes of participants 0–31 months after being pregnant. Results indicate frequency and percent expressing vaccine acceptant attitudes, based on dichotomized Likert scale scores. ^aAttitudinal construct shows > 10% difference in vaccine acceptance based on maternal vaccine timing; included in Pearson chi-square test for independence.

Perceptions of SARS-CoV-2 varied. Five participants (n = 5%) had previously been diagnosed with SARS-CoV-2, four of whom were vaccinated while lactating. While 83% (n = 83) worried about contracting SARS-CoV-2 themselves, 36% (n = 36) believed SARS-CoV-2 infection is not dangerous for people who have recently given birth. Confidence that SARS-CoV-2 vaccines were rigorously tested before being approved for public rollout was lower than for vaccines in general (84% vs. 96%), although most believed that vaccination against SARS-CoV-2 would help protect themselves (n = 96, 96%) and their children (n = 92, 92%) from infection.

Factors Associated With Vaccine Timing

Among examined baseline characteristics, vaccination during pregnancy was associated with employment in healthcare (OR = 2.53, 95% CI [1.12, 5.73]). Those vaccinated while lactating were more likely to have experienced pregnancy complications (e.g., hypertension, preeclampsia, gestational diabetes) during their most recent pregnancies (OR = 3.14, 95% CI [1.23, 7.97]) or be over 35 years old (OR = 2.38, 95% CI [1.04, 5.48]). Given a Bonferroni correction of alpha equal to 0.01, however, correlations between vaccine timing and baseline characteristics were not found to be statistically significant.

Five attitudinal constructs showed greater than 10% difference in vaccine acceptance based on the timing of maternal SARS-CoV-2 vaccination and were selected for further analysis, with an adjusted alpha of 0.01 after Bonferroni correction (Table 3). Of these, Pearson chi-square testing showed a statistically significant correlation between respondents who disagreed or doubted that a maternal SARS-CoV-2 vaccine would protect their breastfeeding infants and vaccination during lactation, rather than pregnancy (X² = 6.83, p = .01).

Discussion

In the present study we explored motivations of pregnant and lactating individuals to seek SARS-CoV-2 vaccination, the guidance they received, and their vaccine attitudes. Regardless of SARS-CoV-2 vaccination timing, most participants asserted a strong belief in the importance, efficacy, and safety of vaccines, including SARS-CoV-2 vaccines. Yet, even in this fully vaccinated cohort, some vaccine hesitancy persisted. Bivariate analysis failed to identify statistically significant sociodemographic differences between those vaccinated in pregnancy as opposed to lactation, but showed that respondents who doubted that vaccines could provide passive immune protection to their infants were more likely to be vaccinated during lactation.

Our study, like others during the pandemic, is limited by variation in disease severity and recommendations. Our study was undertaken during a time when access and recommendations for SARS-CoV-2 vaccination changed locally. In December 2020, mRNA and adenovirus vectored SARS-CoV-2 vaccines became available to healthcare workers and those with high-risk medical conditions, including pregnancy. On April 13, 2021, all Pennsylvanians aged 16 years or older became eligible for vaccination (PDoH, 2022). On April 23, 2021, the CDC officially recommended vaccination for all pregnant people in consultation with their clinician (National Center for Immunization and Respiratory Diseases, 2022). During survey administration, case positivity for SARS-CoV-2 on PCR and antigen testing ranged from 6.5% in April to 1.1% in August 2021, suggesting low prevalence, and delta and omicron variants were not circulating (ACHD, 2022a). With increased complications of adverse outcomes in pregnancy associated with the delta variant, physician counseling may have changed since our survey was administered. Regardless, the hesitation and concern displayed by our universally vaccinated sample, even during a low prevalence period without delta or omicron variants, suggests that additional guidance and patient-centered communication about maternal vaccination is needed.

The relationship between maternal and infant immunity complicates vaccination decision making for lactating people, and few investigators have directly interrogated their vaccine beliefs. Sutton et al. (2021) found that race, language, and prior influenza vaccination were determinants of SARS-CoV-2 vaccine acceptance for pregnant and lactating people. We expand on these participant demographics to weigh identified factors for vaccination acceptance. We suggest that this cohort felt motivated to protect themselves and their new infants from SARS-CoV-2 infection, whereas the opinions and health of family/friends were viewed as less influential. This suggests that counseling about maternal–child health benefits may be more effective than messaging about the benefits of maternal vaccination for community health.

Of note, we did not include individuals who declined vaccination in our study, given that our sample was drawn from a cohort study measuring post-vaccination SARS-CoV-2 antibody titers in human milk. Previously, researchers have suggested that vaccine side effects on maternal or fetal health, lack of research, and speed of vaccine development were associated with SARS-CoV-2 non-vaccination (Sutton et al., 2021). Yet, similar themes were seen in our sample, suggesting that these concerns may be universal.

Prevalence of maternal safety concerns regarding influenza vaccination in lactation found by Gorman and Chambers (2015) was comparable to that of SARS-CoV-2 in the present study (10% vs. 12%, respectively). Our respondents’ confidence in the safety of SARS-CoV-2 vaccination for breastfeeding infants was also similar to that reported for maternal influenza vaccination in Gorman et al. and Chambers. (2015; 91% vs. 89%, respectively). Again, these similarities suggest that the safety of vaccinations for lactating recipients and their breastfed infants is a perennial concern for this population, regardless of type of infection or recency of vaccine development.

Compared to previous U.S. surveys of pregnant people’s attitudes toward influenza and Tdap vaccination in pregnancy, respondents in our cohort demonstrated more confidence in the safety of maternal vaccination and the ability of maternal vaccines to reduce the risk of infant infection (Dudley et al., 2020). The origin of these disparities remains unclear; perhaps differences stem from survey timing (lactation in our study vs. pregnancy in many others), or because SARS-CoV-2 vaccines are better understood on a population level than influenza vaccines because of the contemporary SARS-CoV-2 pandemic and the flood of related media.

The risks SARS-CoV-2 poses to maternal and infant health necessitate vaccine education as standard of care for all pregnant or recently pregnant individuals. In accordance with ACOG recommendations (Riley et al., 2020), initial SARS-CoV-2 vaccine counseling should be noted in the electronic medical record and providers should continue to offer vaccination to unvaccinated persons in subsequent visits. There is a critical need for further exploration of these attitudes to help clinicians develop counseling on SARS-CoV-2 vaccine safety that directly addresses the concerns of pregnant and recently pregnant persons.

We found that either counseling about vaccination is not routinely performed or information is not received by those taught. In our study, almost one-third of respondents received no SARS-CoV-2 vaccine guidance from a healthcare provider, and of those who did, many received information but no final recommendation about vaccination. In light of these results, we call for patient-centered education about maternal vaccination as a standard component of peripartum and pediatric care.

We have highlighted the importance of research about maternal vaccine attitudes and uptake but did not include participants who declined SARS-CoV-2 vaccination; in addition, our sample size was too small to control for additional comorbidities that increase risks infection. Future work looking at SARS-CoV-2 vaccine beliefs and attitudes in these populations across diverse regions, income and education levels, and racial/ethnic groups is warranted, as is a comparison of the maternal vaccine attitudes of breastfeeding and formula feeding parents. Given prioritization of infant health in parental vaccination decisions, continued exploration of maternal SARS-CoV-2 vaccine antibodies and passive immunity in infants may also play a key role in future vaccine education.

Limitations

The evolving nature of the SARS-CoV-2 pandemic complicated comparison to previous studies about maternal attitudes towards influenza or pertussis vaccination in pregnancy. Variability of vaccine availability based on individuals pre-existing conditions, delivery dates, and local supply chains undoubtedly influenced the timing of maternal SARS-CoV-2 vaccination and inclusion in this study. Our final sample was limited to participants willing and medically eligible for the parent study on SARS-CoV-2 antibodies in human milk. Finally, participants were solicited within the 1st year of SARS-CoV-2 vaccine rollouts and significant volunteer bias shaped our sample, leading to the overrepresentation of those with higher educational attainment and employment in healthcare, compared to local demographics. Although prior SARS-CoV-2 vaccination was not an eligibility requirement, our final sample was fully vaccinated because no unvaccinated patients volunteered for the study. No attempts were made to quantify or specifically measure breastfeeding.

Conclusions

Despite accepting vaccination against SARS-CoV-2, some lactating people have endorsed concerns about vaccine side effects and safety, with significant variability in reported vaccine education and counseling by healthcare providers. Standard of care for pregnant and recently pregnant people should include vaccine education tailored to their specific concerns vis-à-vis the effects of maternal vaccination on infant health. While the CDC recommends SARS-CoV-2 vaccination for all pregnant people, strong advocacy for vaccination during the immediate postpartum period represents another important means of increasing vaccination coverage for those who decline vaccination during pregnancy.