Nutritional status of infants at six months of age following maternal influenza immunization: A randomized placebo-controlled trial in rural Nepal

Evaluating the Concept of Brain Sparing in a High Income Setting, Using Historical Records of Maternal Influenza or Syphilis Infection

INTRODUCTION

In the context of adverse in utero environments, the fetal brain might be preserved at the expense of other tissues. This trade-off, brain sparing, has not been studied in the context of maternal infection. We investigated cases of maternal syphilis in the early 20th century and influenza during the 1918-1920 pandemic, in the Swiss city of Lausanne, a relatively high-income setting. We tested the brain sparing hypothesis, that head circumference is protected at the expense of birth weight.

METHODS

A total of 8530 individual birth records from 1911 to 1922 from the University Maternity Hospital of Lausanne were used. We fitted generalized linear and additive linear models to explain how neonatal size varies under disease exposure.

RESULTS

Influenza reduced head circumference and birth weight among livebirths similarly, by -0.11 and -0.14 standard deviation (SD) units respectively. Conversely, for syphilis-exposed infants, head circumference was affected more than birth weight (-0.61 SD vs. -0.46 SD). Stillborn infants exposed to syphilis experienced a much greater reduction in head circumference (-1.92 SD) than liveborn infants. After adjustment for gestational age, these findings persisted in the case of influenza, but the effects of syphilis were reduced. Furthermore, half of syphilis-exposed infants were born before term, suggesting that lower infant size was partly mediated by shorter gestation. Nevertheless, head circumference among stillbirths exposed to syphilis was still substantially reduced, even after adjustment for gestational age (-1.26 SD).

CONCLUSION

Our findings do not support the brain sparing hypothesis. Moreover, the substantial reduction in head circumference among syphilis-exposed fetuses might help explain why a quarter of them were stillborn.

Dissecting Fc signatures of protection in neonates following maternal influenza vaccination in a placebo-controlled trial

Influenza is an important cause of illness and morbidity for infants. Seasonal influenza vaccination during pregnancy aims to provide protection to mothers, but it can also provide immunity to infants. The precise influence of maternal vaccination on immunity in infants and how vaccine-elicited antibodies provide protection in some but not all infants is incompletely understood. We comprehensively profiled the transfer of functional antibodies and defined humoral factors contributing to immunity against influenza in a clinical trial of maternal influenza vaccination. Influenza-specific antibody subclass levels, Fc ɣ receptor (FCGR) binding levels, and antibody-dependent innate immune functions were all profiled in the mothers during pregnancy and at birth, as well as in cord blood. Vaccination increased influenza-specific antibody levels, antibody binding to FCGR, and specific antibody-dependent innate immune functions in both maternal and cord blood, with FCGR binding most enhanced via vaccination. Influenza-specific FCGR binding levels were lower in cord blood of infants who subsequently developed influenza infection. Collectively these data suggest that in addition to increased antibody amounts, the selective transfer of FCGR-binding antibodies contributes to the protective immune response in infants against influenza.

A systems map of the economic considerations for vaccination: Application to hard-to-reach populations

BACKGROUND

Understanding the economics of vaccination is essential to developing immunization strategies that can be employed successfully with limited resources, especially when vaccinating populations that are hard-to-reach.

METHODS

Based on the input from interviews with 24 global experts on immunization economics, we developed a systems map of the mechanisms (i.e., necessary steps or components) involved in vaccination, and associated costs and benefits, focused at the service delivery level. We used this to identify the mechanisms that may be different for hard-to-reach populations.

RESULTS

The systems map shows different mechanisms that determine whether a person may or may not get vaccinated and the potential health and economic impacts of doing so. The map is divided into two parts: 1) the costs of vaccination, representing each of the mechanisms involved in getting vaccinated (n = 23 vaccination mechanisms), their associated direct vaccination costs (n = 18 vaccination costs), and opportunity costs (n = 5 opportunity costs), 2) the impact of vaccination, representing mechanisms after vaccine delivery (n = 13 impact mechanisms), their associated health effects (n = 10 health effects for beneficiary and others), and economic benefits (n = 13 immediate and secondary economic benefits and costs). Mechanisms that, when interrupted or delayed, can result in populations becoming hard-to-reach include getting vaccines and key stakeholders (e.g., beneficiaries/caregivers, vaccinators) to a vaccination site, as well as vaccine administration at the site.

CONCLUSION

Decision-makers can use this systems map to understand where steps in the vaccination process may be interrupted or weak and identify where gaps exist in the understanding of the economics of vaccination. With improved understanding of system-wide effects, this map can help decision-makers inform targeted interventions and policies to increase vaccination coverage in hard-to-reach populations.

Vitamin A Supplementation during Pregnancy Enhances Pandemic H1N1 Vaccine Response in Mothers, but Enhancement of Transplacental Antibody Transfer May Depend on When Mothers Are Vaccinated during Pregnancy

Background

In the growing embryo, the vitamin A requirement is tightly regulated. Maternal vitamin A deficiency during pregnancy may alter maternal immune function to accommodate the fetus.

Objective

Our primary objective was to determine the effect of oral vitamin A supplementation (VAS) during pregnancy and until 6 mo postpartum on pandemic H1N1-vaccine responses in mothers and their infants at 6 mo of age.

Methods

In this randomized controlled clinical trial, pregnant women (n = 112) during the second trimester (mean ± SD: 14 ± 1 wk) were assigned to receive either an oral dose of 10,000 IU vitamin A or placebo weekly until 6 mo postpartum. During the third trimester, mothers received a single dose of inactivated pandemic H1N1-influenza vaccine. Hemagglutination-inhibition (HAI) titer was measured in cord, infant, and maternal blood samples. Multivariate regressions with adjustments were used for data analysis.

Results

Seventy-six percent of women had low plasma retinol concentrations (<1.05 μmol/L) in their second trimester. VAS of mothers increased vitamin A concentrations in cord blood by 21.4% and in colostrum by 40.7%. At 6 mo postpartum, women in the vitamin A group had 38.7% higher HAI titers and a higher proportion of HAI titer of ≥1:40 of the cutoff compared with the placebo group. A total of 54.5% of infants had an HAI titer ≥1:40 at 6 mo of age, but there was no difference in HAI titer in infants between groups. Overall, HAI in cord blood did not differ between groups, but in the placebo group, cord blood HAI was negatively associated with maternal "vaccination-to-delivery intervals" (rs = -0.401; P = 0.5), and maternal VAS increased cord blood HAI 6-fold if antenatal immunization was administered ≥10 wk before delivery.

Conclusions

In a community with low vitamin A status, weekly maternal VAS during pregnancy and postpartum increases the breast-milk vitamin A concentration and enhances prenatal H1N1-vaccine responses in mothers, but the benefits of maternal VAS in transplacental antibody transfer may depend on the time of gestation when mothers were vaccinated. This trial was registered at clinicaltrials.gov as NCT00817661.

Clinician perspectives on strategies to improve patient maternal immunization acceptability in obstetrics and gynecology practice settings

Pregnancy is an ideal time to communicate with women about vaccines for themselves and their infants, yet maternal immunization rates remain suboptimal. This study aimed to identify clinic, provider, and staff-related attributes and facilitators to be utilized for a comprehensive vaccine intervention in ob-gyn clinical settings. We conducted in-depth interviews with 24 providers, both healthcare providers (e.g., physicians, nurse practitioners, midwives) and practice managers, from urban and suburban ob-gyn practices in Georgia and Colorado about their immunization attitudes, practices, and patient experiences. Qualitative analyses included Pearson correlation tests to evaluate patterns and relationships within the data to determine themes. Six major themes emerged: 1) strong provider "buy in" for maternal immunization; 2) the supporting role of clinical/interpersonal cues for vaccine promotion; 3) varying provider-patient communication approaches and its influence on maternal and pediatric uptake; 4) an urgent need for a designated office immunization champion; 5) reimbursement and practice implementation challenges; and 6) region differences in attitudes and values toward maternal immunization. Although providers expressed strong support for maternal immunization practices and offered environmental cues for vaccine promotion, practices often lacked a designated, structured role for an immunization champion equipped to manage delicate conversations with patients. The findings reflect needs for immunization champion identification, training, and support, along with best practices guidelines to improve coordination of vaccine promotion and delivery efforts in ob-gyn provider offices. Additionally, provider training on communication approaches to enhance acceptance and uptake of maternal vaccines is warranted.