Protecting pregnant people & infants against influenza: A landscape review of influenza vaccine hesitancy during pregnancy and strategies for vaccine promotion

ABSTRACT

Before COVID-19, influenza vaccines were the most widely recommended vaccine during pregnancy worldwide. In response to immunization during pregnancy, maternal antibodies offer protection against potentially life-threatening disease in both pregnant people and their infants up to six months of age. Despite this, influenza vaccine hesitancy is common, with few countries reporting immunization rates in pregnant people above 50%. In this review, we highlight individual, institutional, and social factors associated with influenza vaccine hesitancy during pregnancy. In addition, we present an overview of the evidence evaluating interventions to address influenza vaccine hesitancy during pregnancy. While some studies have indicated promising results, no single intervention has consistently effectively increased influenza vaccine uptake during pregnancy. Using a social-ecological model of health framework, future strategies addressing multiple levels of vaccine hesitancy will be needed to realize the potential health benefits of prenatal immunization programs.

Plain Language Summary

Pregnant people are a high priority group for influenza vaccination annually. Although vaccination can protect both mother and infant, vaccination rates are suboptimal during pregnancy. Previous research has suggested reasons for suboptimal vaccination rates, including concerns about the safety of vaccination during pregnancy and limited access to, and awareness of, influenza vaccines during pregnancy. Studies that have attempted to increase influenza vaccination rates during pregnancy have mostly shown no effect – with some exceptions. Public health professionals need to reevaluate strategies for improving vaccination rates during pregnancy.

KEYWORDS:

• Influenza vaccine
• maternal immunization
• pregnancy
• vaccine hesitancy
• immunization barriers
• prenatal vaccination
• vaccine promotion

Introduction

Influenza illness causes a significant global burden of disease, contributing to over five million hospitalizations and up to 645,000 deaths annually.^1,2 Population groups where the risk of hospitalization is greatest include older adults, individuals with predisposing medical conditions, certain racial and ethnic minority groups, pregnant people, and infants <6 months old. Pregnancy is a risk factor for severe influenza infection, with pregnant people at a seven-fold increase in the risk of influenza-associated hospital admissions compared to the non-pregnant population.³ This increased susceptibility to severe illness is particularly observable during influenza pandemics.^4,5 For example, although pregnant people account for just 1% of the U.S. population, they accounted for 5% of deaths in the U.S. during the 2009 influenza A/H1N1 pandemic.⁴ Influenza infection during pregnancy impacts both maternal and fetal health.⁶ In addition to an increased risk of maternal health complications, a recent prospective cohort study of three middle-income countries found that prenatal influenza infection was linked with a 10-fold increase in the risk of stillbirth, and was associated with lower birthweight compared to no maternal infection.⁷

Infants <6 months old are also at higher risk of severe influenza compared to other population groups, and the burden of influenza disproportionately affects infants <6 months old compared to older children. Between 4 and 15% of children under the age of five years require medical care for laboratory-confirmed influenza during the influenza season. Hospitalization rates range from 0.4 to 1.0 per 1,000 children under the age of five years;^8,9 Rates of influenza hospitalization are more than three-fold higher among infants <6 months old compared to infants 2–4 years old,⁸ and pediatric influenza-associated deaths are highest among infants <6 months old.¹⁰ Globally, 16% of influenza-associated deaths occur in children <5 years of age, predominantly among infants <6 months old.² Because six months of age is the earliest that effective influenza vaccines can be administered, primary immunization is not possible for infants <6 months old, leaving them susceptible to potentially life-threatening influenza infections (Figure 1).

Figure 1. Direct and indirect health impacts of influenza on infants <6 months of age.

*Predominantly documented during the 2009 influenza A/H1N1 pandemic.

Seasonal influenza immunization offers the best method of protection against severe disease for pregnant people and infants <6 months old. Maternal antibodies produced in response to vaccination have been shown to protect the mother from severe infection.¹¹ Because these antibodies also cross the placenta, they additionally offer passive protection for infants until six months of age.¹² Despite the benefits of influenza immunization for pregnant people and infants <6 months old, hesitancy toward influenza vaccination during pregnancy has been a long-standing, global issue for the successful implementation of influenza vaccination programs.¹³ As defined by the SAGE Working Group on Vaccine Hesitancy, vaccine hesitancy is the delay in acceptance, or refusal of vaccination, despite the availability of vaccination services.¹⁴ Despite the availability of influenza vaccines in more than 75% of high-income countries that have recommendations promoting prenatal immunization,¹⁵ influenza vaccination rates during pregnancy across multiple high-income countries have historically been suboptimal.¹⁶ In the US, only 61% of pregnant people received an influenza vaccine during the 2019–20 influenza season.¹⁷ Similarly suboptimal immunization rates are reported in other high-income countries, including the UK, Canada, and Australia.^18–20 Limited data are available to document influenza vaccination rates among pregnant people in low- and middle-income countries (LMICs). However, immunization rates in LMICs are anticipated to be low, given influenza vaccines are not included in Global Vaccine Alliance (GAVI) support and 4% of GAVI-eligible and only 26% of GAVI-ineligible LMICs have policies recommending influenza vaccination during pregnancy.¹⁵ Closing the maternal influenza vaccination gap is a global public health priority.

This review highlights the available evidence on the individual and systems-level factors associated with influenza vaccine hesitancy during pregnancy – as well as evidence to support future interventions to improve vaccination rates and improve health outcomes for mothers and infants <6 months old.

Search methodology

We searched online databases, including PubMed, Scopus, and Embase, from inception to 10 September 2022 for articles relevant to two themes: 1) influenza vaccine hesitancy during pregnancy and 2) strategies for increasing vaccine acceptance during pregnancy. Search terms to identify factors associated with influenza vaccine hesitancy included keywords related to “influenza,” “vaccine uptake,” “vaccine predictors,” “vaccine hesitancy,” and “pregnancy.” Search terms to identify interventions to increase influenza vaccine acceptance included keywords related to “influenza vaccine,” “intervention,” “strategy,” and “pregnancy.” We additionally searched clinicaltrials.gov to identify ongoing randomized controlled trials that aim to increase vaccine acceptance during pregnancy. We provide a narrative synthesis of articles and ongoing studies identified through this search.

Factors associated with prenatal vaccine hesitancy

The factors associated with influenza vaccine acceptance and hesitancy during pregnancy have been extensively evaluated, particularly following the 2009 influenza A/H1N1 pandemic. A systematic review identified key categories of factors associated with prenatal vaccine hesitancy, including vaccine access and convenience, individual and cultural values, health literacy, social influences, emotions regarding vaccination, and perceptions of vaccine risk and benefit and personal vaccination history.²¹ Guided by the Health Belief Model, these factors can be grouped into modifying factors, individual beliefs, and cues to action (Figure 2).²²

Figure 2. Health belief model outlining individual factors influencing influenza vaccine behavior.

Modifying factors

Much of the existing literature has focused on individual-level factors that modify the probability of influenza vaccination during pregnancy.^13,23,24 Studies of sociodemographic factors associated with vaccine hesitancy have identified younger age, higher parity, and being unmarried/partnered and/or unemployed. Additionally, delayed and inadequate prenatal care as well as lack of preexisting medical conditions are positively associated with influenza vaccine hesitancy during pregnancy.²³ In 2020, although 61% of pregnant people in the U.S. received an influenza vaccine, notable social and economic disparities exist. In 2020, immunization rates were lowest among pregnant people who were: Black (53%), ages 18–24 (55%), unmarried (49%), with a high-school education or less (46%), and those who were unemployed (51%), living below poverty or relying on public health insurance (48%), and living in a rural area of the U.S. (57%).¹⁷

A history of influenza vaccination is one of the strongest predictors of influenza vaccine acceptance among pregnant and non-pregnant adults.^23,25 Among pregnant people, the odds of receiving an influenza vaccine are nearly four times higher for those who have previously received an influenza vaccine.²¹ However, this behavior may not apply to immunization history outside of pregnancy. Some studies have shown that acceptance of seasonal influenza vaccine in a prior pregnancy is not associated with receipt of seasonal influenza vaccines in a future pregnancy.²¹ While much of the evidence supporting these factors have been documented in high-income countries, a recent systematic review of 11 studies reported similar factors associated with influenza vaccine hesitancy during pregnancy in low- and middle-income countries.²⁶

Because influenza vaccines are administered seasonally, vaccination is most likely to occur during pregnancies that coincide with influenza vaccine availability, typically offered several months before the start of the influenza season. Several studies have documented the influence of gestational age and calendar time on the likelihood of receiving seasonal influenza vaccination during pregnancy.^27–29 Furthermore, vaccination rates tend to be highest during the second and third trimesters, with multiple factors contributing to differences in vaccine uptake by gestational age. The observed hesitancy to vaccinate early in pregnancy has been linked with patient and provider concerns about safety for vaccination for early fetal development.^30,31 In addition, several national policies, predominantly in parts of Europe, have specifically excluded the first trimester in their recommendation of influenza vaccination during pregnancy.³² As a result, vaccination rates are lowest among those in the first trimester of pregnancy at the start of influenza vaccine campaigns.²⁷

Health literacy is another important individual factor that has been linked with influenza vaccination hesitancy during pregnancy. The odds of influenza vaccination are more than five times higher among pregnant people who have general information about the vaccine and three times higher among pregnant people who are aware of national vaccine recommendations.²¹ Surveys of pregnant people from around the world have consistently documented low awareness of influenza vaccine recommendations during pregnancy,^29–35 with one survey in China indicating awareness of vaccine recommendations was as low as 15% among pregnant patients.³⁶

Individual beliefs associated with maternal influenza vaccine hesitancy

Individual beliefs are influential in the likelihood of influenza vaccination, and some have previously suggested that individual beliefs are more influential than sociodemographic factors.³⁷ Numerous studies have documented concerns about the safety of influenza vaccination during pregnancy as one of the most influential factors driving vaccine hesitancy. Concerns about the safety of vaccines administered during pregnancy have been commonly cited by both pregnant patients and healthcare providers.^13,24,38 The odds of influenza vaccination are lower for pregnant people who believe influenza vaccine is unsafe or causes birth defects or miscarriage.²¹ Concerns about side effects of influenza vaccination in general are associated with a 2–3 fold lower odds of influenza vaccination.²¹

Perceived susceptibility to influenza, perceived severity of disease, and perceived benefits of influenza vaccination are also influential factors.³⁸ Vaccination is more common when pregnant people believe the influenza vaccine is effective, has benefits for the mother, and has benefits for their infant.²¹ Pregnant people who believe they are susceptible to seasonal influenza have nearly two-fold greater odds of influenza vaccination compared to those who do not feel they were susceptible to influenza infection.²¹ Further, pregnant people who believe that seasonal influenza can be harmful to their pregnancy or their unborn infant are nearly four times more likely to receive seasonal influenza vaccine.²¹

Cues to action

The strongest predictor of influenza vaccination during pregnancy is receipt of a recommendation from a healthcare provider.²¹ A meta-analysis of 49 studies found that the odds of influenza vaccination was 12 times higher among those who received a healthcare provider recommendation compared to those who received no recommendation.²¹ Qualitative research has indicated that the offer of vaccination by a healthcare provider during a prenatal care visit was often a key factor in the final decision to vaccinate.²¹ Recommendation by healthcare providers serves multiple roles; they are a cue to action, can improve health literacy, and be used to address concerns about vaccine safety and efficacy.

Despite the strong link between a healthcare provider recommendation and influenza vaccine acceptance during pregnancy, not all providers recommend influenza vaccination to pregnant patients, and the likelihood of receiving a recommendation is dependent on calendar time, medical risk factors, sociodemographic factors, and the type of prenatal care provider.^29,39 For example, a recent study in Germany showed that between 2015 and 2018, just 20% of the pregnant individuals received a vaccine recommendation during their pregnancy. Just as individual-level factors have been linked with vaccine hesitancy, similar individual-level factors have been associated with receipt of a vaccine recommendation from a healthcare provider. Having a high-risk pregnancy, not being foreign-born, and conception in spring are each associated with a higher likelihood of receiving a healthcare provider recommendation for influenza vaccination.^29,39 Black and uninsured pregnant people are also less likely to report receipt of an influenza vaccine recommendation by a healthcare provider.^20,40

Although obstetric policymaking bodies, such as the American College of Obstetricians and Gynecologists (ACOG) and the World Health Organization (WHO) recommend influenza vaccination during pregnancy,⁴¹ some providers express hesitation in recommending influenza vaccination to pregnant patients or report challenges in administering vaccines. Historical surveys conducted between 2003 and 2006 have shown that 5–6% of U.S. obstetricians feel vaccines should not be given during pregnancy, and 50–68% do not feel influenza vaccine should be administered during the first trimester.^42,43 While support for influenza vaccination has increased among obstetricians, the proportion of prenatal care providers outside the U.S. who recommend or administer influenza vaccines to pregnant patients can be much lower (<70%).^44–46

Several institutional barriers may influence the likelihood of a healthcare provider recommendation and/or offer of vaccination. Immunization services increase demands on facilities and staffing, including vaccine purchasing, cold chain storage, and reimbursement. Challenges to vaccine ordering, supply maintenance, and storage are relatively newer challenges to obstetricians,^47,48 and these challenges have been previously linked with lower immunization rates. For example, immunization rates are lower in clinical settings that do not include adequate staffing or workload allocation to support immunization service provision.^38,49

Prenatal care providers who are not obstetricians also have an influential role in reducing influenza vaccine hesitancy among pregnant patients. Although more than 60% of pregnant people say they would have been vaccinated if a midwife or primary care provider recommended the vaccine, several studies have shown that midwives and primary care providers hesitate to recommend vaccines to pregnant patients.^50,51 Pregnant people who receive most of their prenatal care from a primary care provider or midwife are less likely to be recommended influenza vaccine compared to those receiving prenatal care from an obstetrician.³⁹ Although midwives express interest in advising pregnant patients on influenza vaccination, previous surveys in multiple countries have documented barriers, including logistical, interprofessional, and educational barriers.^52–55 Different views on which healthcare provider is responsible for offering influenza vaccination for pregnant patients have been cited by primary care providers, obstetricians and midwives.^50,51 Regardless, lack of a healthcare provider recommendation presents a missed opportunity for vaccination.

Other potential sources of cues to action include spouses/partners, family members, and pregnant peers. However, these social cues to action have been less commonly evaluated for influenza vaccine hesitancy during pregnancy. While one small qualitative study indicated that family and friends have little influence on decision to vaccinate,⁵⁶ having family and friends vaccinated against COVID-19 has been identified as a protective factor against COVID-19 vaccine hesitancy during pregnancy. The potential influence of partners, peers, family, and society on influenza vaccine hesitancy during pregnancy should be further evaluated.

Socioeconomic & regional disparities in maternal influenza immunization

Several of the individual and provider-level factors discussed impact select population groups more than others. Disparities in influenza vaccination rates are influenced by various social determinants of health (SDoH), most specifically neighborhood and built environment, economic instability, healthcare access and quality, language and literacy, and race/ethnicity and discrimination.⁵⁷ Studies have consistently shown that individuals with greater social and economic vulnerability who have publicly funded or no insurance coverage are less likely to receive influenza vaccination during pregnancy.^58–61 This may be particularly problematic in rural settings, where pregnant people rely more heavily on publicly funded prenatal care and primary care providers and more frequently experience healthcare professional shortages.^61–63 As a result, pregnant people in rural areas may experience fewer opportunities to receive vaccines, may not be recommended or offered influenza vaccine as frequently as urban-residing pregnant people, and may be less aware of vaccine recommendations – all factors positively associated with influenza vaccination during pregnancy.^39,61 These barriers can be seen in lower immunization rates observed in rural areas. For example, a recent analysis of U.S. data indicated that the absolute prevalence of influenza vaccination was 4% lower among rural-residing pregnant people compared to urban-residing pregnant people.⁶⁴

One of the greatest disparities in influenza immunization rates reported has been by race. Black pregnant people in the U.S. consistently have the lowest rate of influenza immunization during pregnancy and are less likely to receive recommendations from healthcare providers.^40,65,66 Even after receiving a provider recommendation, influenza immunization rates among Black pregnant people are 9% lower compared to white pregnant people.¹⁷ A survey of pregnant people in two U.S. states (Georgia and Colorado) showed that Black and Latina/x pregnant people are less confident in vaccine safety and efficacy and have a lower perceived risk of disease compared to white pregnant people.⁶⁷ These observations may be influenced by medical mistrust, an issue highlighted during the COVID-19 pandemic.^68,69

In addition to disparities within countries and regions, significant global disparities exist regarding access to influenza vaccines during pregnancy. Despite global recommendations by the WHO,⁷⁰ as of 2014, only 4% of low and lower-middle-income countries who were GAVI-eligible countries, 26% of countries from low and lower-middle-income countries who were not GAVI-eligible and 50% of upper-middle-income countries had a policy recommending influenza vaccination during pregnancy.¹⁵ Among WHO Member States, 6% of Member States in the Africa region, 18% of Member States in the South-East Asian region, and 38% of Member States in the East Mediterranean region have influenza vaccine policies targeting pregnant people.¹⁵ Low rates of vaccine recommendations are likely to be driven by limited data on influenza burden, healthcare infrastructure and complex vaccine supply issues in low- and middle-income countries.⁷¹

Influence of the COVID-19 pandemic on maternal influenza vaccine hesitancy

Multiple studies have documented the disruption to childhood immunization programs resulting from the COVID-19 pandemic,^72–77 indicating that in 2020 alone, coverage of recommended childhood immunizations has declined globally by 2.7%.⁷⁸ However, fewer studies have documented the impact on adult immunization services. One UK study of 1,404 recently pregnant people found that 40% of respondents had a pregnancy vaccination appointment canceled by their provider, 21% reported difficulty accessing pregnancy vaccinations, and 45% experienced fear related to attending pregnancy vaccination appointments during the pandemic.⁷⁹ A small international survey of 48 clinicians found that more than 50% of clinicians reported challenges delivering recommended prenatal vaccines during the COVID-19 pandemic, including issues with patient access to immunization services due to social distancing and lockdown measures and fear of infection, clinical staff shortages, and vaccine supply issues.⁸⁰ Post-pandemic declines in influenza immunization have been documented in the Vaccine Safety Datalink data, with 66% of pregnant people vaccinated in the 2019–20 season, 61% in the 2020–21 season, and 52% in the 2021–22 influenza season. Despite these rates, the COVID-19 pandemic may positively influence influenza vaccine acceptance in the future. Additional surveys have shown that pregnant people report greater trust in healthcare providers in providing vaccine information after the COVID-19 pandemic.⁸¹ This may be an indication that the COVID-19 pandemic could potentially improve influenza immunization rates among pregnant people, but more research is needed.

Promoting influenza immunization during pregnancy

Influential factors driving influenza vaccine behavior during pregnancy can be addressed at multiple levels, from the individual to society. Drawing from Bronfenbrenner’s Ecological Systems Theory and the Ecological Model of Health Behaviors, the Social-Ecological Model of Health Promotion can serve as a useful framework for implementing multi-level interventions to increase influenza vaccine uptake among pregnant people. The socio-ecological model of health identifies myriad factors that influence health at five intersecting levels: (1) individual, (2) relationship/interpersonal, (3) institutional, (4) community, and (5) society (Figure 3).⁸² Examining each level of the Social-Ecological Model can help to develop targeted interventions to address vaccine hesitancy during pregnancy.

Figure 3. Social-ecological model as a framework for influenza vaccine promotion during pregnancy.

The individual-level constitutes a pregnant persons’ health status and sociodemographic factors, as well as their knowledge, skills, and attitudes regarding influenza vaccines. Interventions at this level tend to focus on education and skill-building, possibly utilizing motivational interviewing. The relationship or interpersonal-level considers the influence of formal and informal social support networks that have direct contact with the pregnant person, including spouses/partners, family, friends, and peer groups. For pregnant people, interventions at this level may target the health literacy and influence of familial and social networks and leverage the support of pregnant peers.

Moving on to systems-level factors, the institutional-level includes rules and social interactions that occur within institutions, such as schools, workplaces, and healthcare systems. Interventions at this level may address patient-provider communication, provider and staff education, and healthcare information technology (e.g., provider alerts or mHealth interventions). The community-level reflects the larger social system in which pregnant people and their relationships occur. Interventions at this level address local, regional, and federal policy, and may include health plan incentives, access to low-cost or free vaccines, and health policies that promote and support vaccination during pregnancy. Finally, the society-level reflects the macrosystem and cultural context in which pregnant people and their contacts reside, including cultural and social norms. These can directly or indirectly influence individual behavior through policies and programs promoting immunization. Interventions at this level may address social norms by developing tailored social marketing and health communication campaigns.

Data on strategies to increase influenza vaccination during pregnancy

To date, there is limited evidence outlining a consistently effective intervention to address vaccine hesitancy during pregnancy. Previous investigators have classed interventions into three groups: staff education and training, information, and education for patients, and health systems improvements,⁸³ and these interventions have predominantly targeted individual and institutional-level factors and patient-provider communication (Table 1). These interventions have offered mixed and often disappointing results, and despite the benefits of multi-component strategies, it is impossible to disentangle the effects of specific constituent strategies.^40,83,109

Table 1. Summary of strategies for increasing influenza vaccine acceptance during pregnancy^40,83.

Intervention Target	Example Interventions	Amount of Evidence	Effectiveness
Individual	Patient education^Citation84–94	+++	Modest inconsistent increase
	Message framing^Citation95,Citation96	+	No effect
	Motivational Interviewing	-	Effects not currently known in pregnancy*
Relationships	Peer support interventions (i.e., group prenatal care)^Citation97	+	Increase
	Community organization-led interventions	-	Effects not currently known in pregnancy*
Institutional	Staff education and training^Citation85–88–Citation93	++	Modest inconsistent increase
	Provider education^Citation85,Citation86	++	Increase
	Patient immunization reminders (“nudges”)^Citation87–89–Citation98–100	++	Modest inconsistent effect
	Provider alerts to discuss vaccination^Citation87–93–Citation101–104	++	Increase
	Standing orders/midwifery-led vaccination program^Citation103,Citation105,Citation106	++	Increase
	Opt-out vs. opt-in vaccination policies^Citation107	+	No effect
	Institutional vaccine “champion”^Citation85,Citation86,Citation106	+	No effect
	Interventions to increase access to vaccines at clinic/health service^Citation87,Citation88	+	Increase
	Workplace vaccination policies	-	Effects not currently known in pregnancy*
Community	Provision of low-cost or free vaccines to pregnant persons^Citation108	+	Increase
	Health policies encouraging vaccination during pregnancy^Citation108	+	Increase
	Health plan incentives	-	Effects not currently known in pregnancy*
Society	Mass media campaigns	-	Effects not currently known in pregnancy*
	Social marketing	-	Effects not currently known in pregnancy*

*Effects have been documented in general population, but to our knowledge, have not been evaluated among pregnant persons specifically.

Individual and institutional-level factors which have shown some positive effects on influenza vaccination rates include patient and provider reminders (i.e., “nudges”), midwifery-led immunization services, and patient and provider education.^83–93 Similar strategies have been evaluated for pertussis vaccine promotion during pregnancy and have been found to be effective.¹⁰⁹ For example, a randomized controlled trial of 321 pregnant people showed that patient education was effective in doubling influenza vaccination rates during pregnancy.⁸⁴

More recently, there has been work to deploy motivational interviewing interventions in clinical settings to promote prenatal immunization.⁹⁴ Motivational Interviewing (MI) is an evidence-based practice that originated from alcohol and substance-abuse counseling⁹⁵ and is increasingly used in a range of health-related behavioral interventions.^96,97 MI is a technique that aims to support decision-making by applying a person-centered collaborative approach to behavior change using open-ended questions, affirmations, reflections, and summaries (i.e., OARS) to promote self-efficacy and motivation to adopt positive health behaviors.^54,94,98,99 Although multiple experimental and quasi-experimental studies have shown MI can effectively be used to address parental vaccine hesitancy,^100–102 the effects of MI have not yet been well described in pregnant people. Several ongoing trials are currently evaluating the use of motivational interviewing to increase vaccine acceptance during pregnancy. For example, an ongoing pragmatic controlled trial in Colorado (U.S.) will train prenatal care providers to use motivational interviewing with pregnant patients.⁹⁸

Results have not consistently supported a strong effect of these individual and provider-level strategies. Despite some promise,^84,103 results from clinical trials have not consistently identified positive improvement in vaccination rates associated with patient and provider education^{85–87–104} or with immunization reminders or nudges,^105,106 with some concluding that improving patient education and awareness is likely insufficient on its own to address vaccine hesitancy.^13,40 A recent systematic review indicated that although awareness of recommended vaccines during pregnancy is associated with vaccine acceptance, awareness alone is rarely sufficient to drive vaccine behavior.²¹

Fewer studies have targeted the effects that personal relationships can have on vaccine decision-making. One recent chart review in Florida (U.S.) compared vaccination rates among patients who received prenatal care in a CenteringPregnancy approach (i.e., evidence-based group prenatal care) to those who received traditional individualized prenatal care.¹⁰⁷ The investigators observed a 24% absolute increase in influenza vaccine uptake and 12% absolute increase in pertussis vaccine uptake among CenteringPregnancy patients compared to traditional care patients.¹⁰⁷ While these results are promising and may allude to the power of peer influence on medical decision-making, this study was observational and single center, making it difficult to draw firm conclusions.

Although more recently investigators have initiated social media campaigns to address COVID-19 vaccine hesitancy during pregnancy,¹⁰⁸ to our knowledge, the effects of mass and social media campaigns on uptake of influenza vaccines among pregnant people have not yet been evaluated. In response to the COVID-19 pandemic, the One Vax Two Lives social media campaign was created to increase public access to evidence on COVID-19 vaccination during pregnancy.¹⁰⁸ Although the impact of this campaign on COVID-19 vaccination rates during pregnancy have not yet been reported, similar campaigns could be evaluated in the context of other recommended vaccines, including influenza vaccine.

As evidenced by existing data, it is unlikely that interventions solely focusing on individual-level factors or awareness alone will offer significant success. Considering this, strategies for addressing influenza vaccine hesitancy among pregnant people require reevaluation. Future studies should evaluate the effect of interventions targeting multiple levels of factors influencing influenza vaccine hesitancy during pregnancy – from individual to societal.

When considering intervention strategies, it is important to note the interplay between each level. For example, peer interventions (e.g., group prenatal care or new parent classes) leverage interpersonal relationships, but also require institutional buy-in (e.g., provider recruitment and education) and community-level supports (e.g., insurance coverage of group care) to be viable. As another example, health literacy interventions using motivational interviewing may require addressing both the institutional (e.g., staff and provider training) and individual-levels (e.g., assessing potential change in knowledge, attitudes, and skills). Looking forward, multi-component interventions which target the overlapping levels of the social ecological environment may offer more success than individual-level interventions alone in reducing influenza vaccine hesitancy during pregnancy, thereby improving health outcomes among pregnant people and infants <6 months old.

Conclusions

Pr7enatal influenza immunization has the potential to protect against severe illness in pregnant people and infants <6 months old. Despite its promise, vaccine hesitancy during pregnancy has historically hindered the health impacts of prenatal immunization, and few studies have identified interventions that can consistently increase vaccination rates during pregnancy. As a result, reconsideration of previously evaluated strategies to address influenza vaccine hesitancy during pregnancy is needed. Given the population health benefits maternal influenza immunization can offer research and investment into innovative and effective, multilevel interventions remains vital to support global maternal and infant health.

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No potential conflict of interest was reported by the authors.

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Funding

The author(s) reported that there is no funding associated with the work featured in this article.