Pregnant women's attitudes toward influenza vaccination while breastfeeding

Assessment of human milk samples obtained pre and post-influenza vaccination reveals a poor boosting of seasonally-relevant, hemagglutinin-specific antibodies

Introduction

Influenza (flu) vaccination prevented over 100,000 hospitalizations and 7000 deaths from flu over the 2019-2020 season in the USA. Infants <6 months are the most likely to die from flu, though flu vaccines are only licensed for infants >6 months old. Therefore, it is recommended that flu vaccination occur during pregnancy, as this reduces severe complications; however, vaccination rates are suboptimal, and vaccination is also recommended postpartum. For breast/chest-fed infants, the vaccine is believed to elicit protective and robust seasonally-specific milk antibody (Ab). Few comprehensive studies exist examining Ab responses in milk after vaccination, with none measuring secretory Ab (sAb). Determining whether sAbs are elicited is critical, as this Ab class is highly stable in milk and mucosae.

Methods

In the present study, our aim was to determine to what extent specific Ab titers in the milk of lactating people were boosted after seasonal influenza vaccination. Over the 2019-2020 and 2020-2021 seasons, milk was obtained pre- and post-vaccination and assessed for specific IgA, IgG, and sAb against relevant hemagglutinin (HA) antigens by a Luminex immunoassay.

Results

IgA and sAb were not found to be significantly boosted, while only IgG titers against B/Phuket/3073/2013, included in vaccines since 2015, exhibited an increase. Across the 7 immunogens examined, as many as 54% of samples exhibited no sAb boost. No significant differences for IgA, sAb, or IgG boosting were measured between seasonally-matched versus mismatched milk groups, indicating boosting was not seasonally-specific. No correlations between IgA and sAb increases were found for 6/8 HA antigens. No boost in IgG- or IgA-mediated neutralization post vaccination was observed.

Discussion

This study highlights the critical need to redesign influenza vaccines with the lactating population in mind, wherein the aim should be to elicit a potent seasonally-specific sAb response in milk. As such, this population must be included in clinical studies.

Written Briefing and Oral Counseling Increase the Willingness to Receive the SARS-CoV-2 Vaccination among Women in Puerperium: A Qualitative Prospective Cohort Study

(1) Background: Vaccination rates for severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) are low in Austria. International obstetric societies recommend the SARS-CoV-2 mRNA vaccination for women in puerperium. (2) Methods: A prospective two-stage cohort study was conducted at the Medical University of Vienna between October 2022 and December 2022. Firstly, women in puerperium were assigned to the evaluation group (step 1), and secondly, another cohort of unvaccinated women were randomly assigned to study group A (written briefing) or B (written and oral briefing) (step 2). We evaluated the vaccination status among women in the evaluation group and the willingness to receive the vaccination in all three cohorts. (3) Results: We included 217 women in puerperium (evaluation: n = 69, A: n = 68; B: n = 80). In the evaluation group, 66.7% (n = 46/69) of the women were unvaccinated. A total of 45.7% (21/46) of the unvaccinated women categorically declined the SARS-CoV-2 vaccination. A total of 26.5% (n = 18/68) of women in study group A, and 43.8% (n = 35/80) of women in study group B expressed their willingness to receive the vaccination (p = 0.029). There were no differences in willingness to receive the vaccination between different age strata of women in study groups A and B. (D) Conclusion: Our qualitative data demonstrate a benefit from oral counseling in addition to written briefing in order to increase the willingness to receive the vaccination among women in puerperium.

Association Between Influenza Vaccination During Pregnancy and Breastfeeding Duration

Background: Prenatal vaccination and breastfeeding are both health promotional behaviors. The benefits of breastfeeding are widely investigated and well established, as well as the effectivity and the safety of the influenza vaccination. This study aimed to investigate the association between the prenatal health behavior of influenza vaccination and breastfeeding duration for at least 3 months in the United States. Methods: A secondary data analysis was conducted using 2016-2019 Pregnancy Risk Assessment and Monitoring System data consisting of 83,976 postpartum women. Results: Overall, 68.3% (n = 57,269) breastfed for at least 3 months and 56.6% (n = 48,834) received the influenza vaccine during pregnancy. Women who did not receive the influenza vaccine during pregnancy were significantly less likely to breastfeed compared with women who received the vaccine during pregnancy (64.5% versus 71.1%; p < 0.001). Significant covariates associated with ≥3-month breastfeeding duration included maternal sociodemographic factors, infant factors, maternal health factors, and prenatal health behaviors. In the multivariable logistic regression analyses, the odds of breastfeeding at least 3 months were significantly lower in women who did not receive the influenza vaccine during pregnancy compared with those who were vaccinated (odds ratio, 0.92; 95% confidence interval, 0.88-0.98; p = 0.005). Discussion: Findings from this large, nationally representative sample of U.S. mothers indicate an association between the health-promotional behaviors of prenatal influenza vaccination and breastfeeding duration postpartum. Recommendations and education by health care providers should include a focus on maternal health behaviors to support positive maternal-infant health outcomes including reduced risk of infection and extended breastfeeding duration.

Racial/Ethnic Disparities in Maternal Vaccine Knowledge, Attitudes, and Intentions

OBJECTIVES

Although disparities in maternal vaccine acceptance among racial/ethnic groups are well documented, the reasons for these disparities are unclear. The objective of this study was to describe differences in pregnant women's knowledge, attitudes, beliefs, intentions, and trust regarding maternal and infant vaccines by race/ethnicity.

METHODS

We collected survey data from 1862 pregnant women from diverse prenatal care practices in Georgia and Colorado from June 2017 through July 2018. We performed multiple logistic regressions to determine differences in intentions, knowledge, attitudes, beliefs, and trust by race/ethnicity and calculated odds ratios (ORs) and 95% CIs.

RESULTS

Compared with White women, Black and Hispanic women were less confident in vaccine safety and efficacy and less likely to perceive risk of acquiring vaccine-preventable diseases, report provaccine social norms, indicate having enough vaccine knowledge, and trust vaccine information from health care providers and public health authorities. Black women were the least confident in the safety of the maternal influenza vaccine (OR = 0.37; 95% CI, 0.27-0.49); maternal tetanus, diphtheria, and acellular pertussis vaccine (OR = 0.37; 95% CI, 0.27-0.52); and infant vaccines overall (OR = 0.40; 95% CI, 0.28-0.58), and were least likely to intend to receive both maternal vaccines (OR = 0.35; 95% CI, 0.27-0.47) or all infant vaccines on time (OR = 0.45; 95% CI, 0.34-0.61) as compared with White women.

CONCLUSIONS

Understanding differences in behavioral constructs integral to vaccine decision making among women of different races/ethnicities can lead to tailored interventions to improve vaccine acceptance.

Randomized trial comparing the safety and antibody responses to live attenuated versus inactivated influenza vaccine when administered to breastfeeding women

BACKGROUND

Live attenuated influenza vaccine (LAIV) and inactivated influenza vaccine (IIV) are both licensed for administration to nursing mothers. Little is known about the potential for transmission of LAIV viruses from the mother to the infant and the comparative breast milk antibody responses to LAIV and IIV.

METHODS

We performed a randomized, double-blind study comparing the immunogenicity of LAIV to IIV when administered to nursing mothers. The safety of LAIV to IIV in women and their infants was also compared. Women received LAIV + intramuscular placebo, or IIV + intranasal placebo on Day 0. Breast milk and nasal swabs (from women and infants) were collected on Days 0, 2, and 8 for detection of LAIV. Breast milk and serum antibody responses were measured at Days 0 and 28. The primary hypothesis was that LAIV would provide superior induction of breast milk IgA responses to influenza as compared to IIV when administered to nursing mothers.

RESULTS

Breast milk IgG, breast milk IgA (H1N1 only), serum hemagglutination inhibition (HAI), and serum IgG responses were significantly higher following administration of IIV compared to LAIV. Receipt of either LAIV or IIV was safe in women and their infants. One (1%) LAIV recipient transmitted vaccine virus to her infant who remained well. No influenza virus was detected in breast milk.

CONCLUSIONS

Breast milk and serum antibody responses were higher for IIV compared to LAIV. LAIV and IIV were safe for nursing women but there was one (1%) possible transmission of LAIV to an infant. This study suggests that IIV may be the preferred vaccine for nursing mothers.

Barriers of Influenza Vaccination Intention and Behavior - A Systematic Review of Influenza Vaccine Hesitancy, 2005 - 2016

BACKGROUND

Influenza vaccine hesitancy is a significant threat to global efforts to reduce the burden of seasonal and pandemic influenza. Potential barriers of influenza vaccination need to be identified to inform interventions to raise awareness, influenza vaccine acceptance and uptake.

OBJECTIVE

This review aims to (1) identify relevant studies and extract individual barriers of seasonal and pandemic influenza vaccination for risk groups and the general public; and (2) map knowledge gaps in understanding influenza vaccine hesitancy to derive directions for further research and inform interventions in this area.

METHODS

Thirteen databases covering the areas of Medicine, Bioscience, Psychology, Sociology and Public Health were searched for peer-reviewed articles published between the years 2005 and 2016. Following the PRISMA approach, 470 articles were selected and analyzed for significant barriers to influenza vaccine uptake or intention. The barriers for different risk groups and flu types were clustered according to a conceptual framework based on the Theory of Planned Behavior and discussed using the 4C model of reasons for non-vaccination.

RESULTS

Most studies were conducted in the American and European region. Health care personnel (HCP) and the general public were the most studied populations, while parental decisions for children at high risk were under-represented. This study also identifies understudied concepts. A lack of confidence, inconvenience, calculation and complacency were identified to different extents as barriers to influenza vaccine uptake in risk groups.

CONCLUSION

Many different psychological, contextual, sociodemographic and physical barriers that are specific to certain risk groups were identified. While most sociodemographic and physical variables may be significantly related to influenza vaccine hesitancy, they cannot be used to explain its emergence or intensity. Psychological determinants were meaningfully related to uptake and should therefore be measured in a valid and comparable way. A compendium of measurements for future use is suggested as supporting information.