The non-specific effects of maternal immunization on birth outcomes: The evidence, mechanisms, and the implications.

Preterm birth (PTB) and stillbirth remain two of the most important causes of death, morbidity, and disability in childhood. Despite efforts to reduce PTB and stillbirth worldwide, rates of these adverse outcomes remain persistently elevated, independent of income setting. There is an urgent need for more effective interventions to reduce associated neonatal and early childhood morbidity and mortality. Maternal vaccines are a well-established strategy used for prevention of pathogen-specific disease in mothers and infants through transplacental antibody transfer. Beyond these pathogen-specific benefits, some studies have also identified non-specific effects (NSEs) of maternal vaccination protecting against several adverse birth outcomes, including PTB and stillbirth. This paper will review the evidence supporting the NSEs of maternal vaccination on birth outcomes, describe the possible underlying mechanisms, outline the research gaps, and summarize the significance from a global health perspective.

Protective effect of maternal immunization on birth outcomes: A data linkage study.

OBJECTIVE: To explore the impact of maternal immunization on adverse pregnancy outcomes including preterm birth (PTB) and stillbirth. METHODS: The authors performed a data linkage study for women who delivered a singleton baby between January 2017 and May 2021. They used Poisson models to estimate incidence rates of adverse pregnancy outcomes and Cox proportional hazards models to estimate hazard ratios (HRs) with 95% confidence intervals (CIs), accounting for the time-dependent nature of the exposure and adjusting for confounders. RESULTS: This study included 10 938 women who received at least one vaccine, and 4029 unvaccinated women. Influenza vaccine was associated with a significant reduction in stillbirth (adjusted HR [aHR], 0.55 [95% CI, 0.33-0.94]), but not in PTB (aHR, 0.92 [95% CI, 0.77-1.10]). Pertussis vaccine was associated with a significant reduction in PTB (aHR, 0.78 [95% CI, 0.64-0.94]) and a similar point estimate for reduction in stillbirth (aHR, 0.59 [95% CI, 0.31-1.10]), although not significant. CONCLUSION: Reductions in PTB and stillbirth associated with maternal immunization suggest possible protective effects beyond pathogen-specific protection. These findings may strengthen justification for scaling up maternal immunization in low-income settings where there remains a high burden of these adverse pregnancy outcomes.

Alignment of national COVID-19 vaccine recommendations for pregnant and lactating women.

The rapid development and roll-out of coronavirus disease 2019 (COVID-19) vaccines is providing hope for a way to control the pandemic. As pregnant and lactating women are generally excluded from clinical trials, the vaccination programme was launched without adequate safety and efficacy data for pregnant women. Yet many professional organizations have recognized the need for administration of COVID-19 vaccines in pregnancy and have issued their own set of recommendations. The lack of evidence, however, has often led to confused messaging, inconsistent language and differing recommendations across organizations, potentially contributing to delay or refusal to accept vaccination by pregnant women. We summarize those differences and recommend that leaders collaborate at a country level to produce joint recommendations. We use the example of Australia, where two professional authorities along with the government and partners in New Zealand worked towards one message, consistent language and a unified recommendation. The aim was to help health professionals and women who are planning pregnancy or who are currently pregnant or breastfeeding to make an informed decision about COVID-19 vaccination. National advisory groups for immunization, professional obstetric organizations and government bodies should be encouraged to coordinate their statements on COVID-19 vaccination for pregnant and lactating women and to use similar language and phrasing for greater clarity.

La rapidité de développement et de déploiement des vaccins contre la maladie à coronavirus 2019 (COVID-19) entretient l'espoir d'un jour pouvoir contrôler la pandémie. Étant donné que les femmes enceintes et allaitantes sont généralement exclues des essais cliniques, le programme de vaccination a été lancé en l'absence de données adéquates sur l'efficacité et l'innocuité du vaccin au sein de cette catégorie. Pourtant, de nombreuses associations professionnelles ont reconnu la nécessité de vacciner contre la COVID-19 durant la grossesse, et ont émis leurs propres recommandations. L'absence de preuves a toutefois souvent donné lieu à une communication incohérente, à un discours contradictoire et à des recommandations divergentes d'une organisation à l'autre, ce qui pourrait avoir conduit certaines femmes enceintes à retarder ou refuser la vaccination. Dans le présent document, nous exposons ces différences et exhortons les dirigeants à collaborer au niveau national pour formuler des recommandations communes. Nous utilisons l'exemple de l'Australie, où deux autorités professionnelles ont travaillé avec le gouvernement et des partenaires en Nouvelle-Zélande afin de transmettre un message unique, d'adopter un langage cohérent et de fournir des directives homogènes. L'objectif était d'aider les soignants et les femmes enceintes, allaitantes ou planifiant une grossesse à prendre une décision éclairée en matière de vaccination contre la COVID-19. Les organes consultatifs nationaux sur la vaccination, les associations professionnelles d'obstétrique et les pouvoirs publics devraient être encouragés à aligner leurs déclarations concernant la vaccination contre la COVID-19 chez les femmes enceintes et allaitantes, ainsi qu'à employer des termes et énoncés similaires pour davantage de clarté.

El rápido desarrollo y puesta en marcha de las vacunas contra el coronavirus de la enfermedad por coronavirus (COVID-19) está dando esperanzas sobre una forma de controlar la pandemia. Como las mujeres embarazadas y lactantes suelen estar excluidas de los ensayos clínicos, el programa de vacunación se puso en marcha sin datos adecuados de seguridad y eficacia para las mujeres embarazadas. Sin embargo, muchas organizaciones profesionales han reconocido la necesidad de administrar las vacunas contra la COVID-19 durante el embarazo y han emitido su propio conjunto de recomendaciones. Sin embargo, la falta de pruebas a menudo ha ocasionado mensajes confusos, un lenguaje incoherente y recomendaciones diferentes en las distintas organizaciones, lo que puede contribuir a retrasar o rechazar la vacunación de las mujeres embarazadas. Resumimos esas diferencias y recomendamos que los líderes colaboren a nivel de país para elaborar recomendaciones conjuntas. Utilizamos el ejemplo de Australia, donde dos autoridades profesionales, junto con el gobierno y los socios de Nueva Zelanda, trabajaron para lograr transmitir un único mensaje con un lenguaje coherente y una recomendación unificada. El objetivo era ayudar a los profesionales sanitarios y a las mujeres que planean un embarazo o embarazadas o en periodo de lactancia a tomar una decisión informada sobre la vacunación contra la COVID-19. Hay que animar a los grupos consultivos nacionales de inmunización, a las organizaciones profesionales de obstetricia y a los organismos gubernamentales a que coordinen sus declaraciones sobre la vacunación contra la COVID-19 para las mujeres embarazadas y lactantes y a que utilicen un lenguaje y una redacción similares para mayor claridad.

Maternal RSV vaccine development. Where to from here?

Respiratory syncytial virus (RSV) is a common cause of acute lower respiratory tract infection and is responsible for a large proportion of infant morbidity and mortality worldwide. Most RSV-related deaths occur in children under six months, and the majority of these occur in low-income settings. To date, there is no known efficacious treatment for RSV infection; hence, prevention remains an important strategy to reduce the global burden of disease. Monoclonal antibodies and vaccinations are currently the two main approaches for prevention of RSV disease. Maternal RSV vaccination is of particular interest as a strategy to protect infants during their most vulnerable period as this approach has proven highly efficacious in other vaccine-preventable conditions such as pertussis and influenza. As results from ongoing phase III clinical trials become available, important decisions will need to be made about the priority and potential implementation of RSV vaccines alongside other public health measures.