Influenza-Related Morbidity in Pregnancy: A Call for Maternal Immunization

Neonates and young children remain susceptible to many serious infectious diseases preventable through vaccination. In general, current vaccines strategies to prevent infectious diseases are unable to induce protective levels of antibodies in the first 6 months of life. Women vaccinated during pregnancy are capable of producing immunoglobulin antibodies that are transported actively to the fetus, and maternal immunization can benefit both the mother and the child. With few exceptions, maternal immunization is not a routine, because of the concerns related to the safety of this intervention. Ethical and cultural issues make the studies on maternal immunization difficult; however, in the last decade, the development of new vaccines, which are very immunogenic and safe has reactivated the discussions on maternal immunization. In this paper we present a review of the literature about maternal immunization based on MEDLINE data (1990 to 2002). The most important conclusions are: 1) there is no evidence of risk to the fetus by immunizing pregnant women with toxoids, polysaccharide, polysaccharide conjugated and inactive viral vaccines; 2) most viral attenuated vaccines are probably safe too, but data is still insufficient to demonstrate their safety; therefore these vaccines should be avoided in pregnant women; 3) in Brazil, there is a need for a maternal immunization program against tetanus. Many new candidate vaccines for maternal immunization are available, but studies should be conducted to evaluate their safety and efficacy, as well as regional priorities based on epidemiological data.

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Maternal immunization is not the same as immunization in pregnancy

Human Vaccines & Immunotherapeutics ◽

10.1080/21645515.2015.1009802 ◽

2015 ◽

Vol 11 (4) ◽

pp. 1074-1074

Author(s):

Ulrich Heininger

Keyword(s):

Maternal Immunization ◽

In Pregnancy

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Group B Streptococcus vaccination in pregnancy: Moving toward a global maternal immunization program

Vaccine ◽

10.1016/j.vaccine.2012.11.026 ◽

2013 ◽

Vol 31 ◽

pp. D46-D51 ◽

Cited By ~ 23

Author(s):

Flor M. Munoz ◽

Patricia Ferrieri

Keyword(s):

Group B Streptococcus ◽

Immunization Program ◽

Maternal Immunization ◽

Group B ◽

In Pregnancy

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Faculty Opinions recommendation of Maternal immunization earlier in pregnancy maximizes antibody transfer and expected infant seropositivity against pertussis.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.726090693.793552166 ◽

2018 ◽

Author(s):

Euan Wallace ◽

Michelle Giles

Keyword(s):

Maternal Immunization ◽

In Pregnancy

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Flu and Tdap Maternal Immunization Hesitancy in Times of COVID-19: An Italian Survey on Multiethnic Sample

Vaccines ◽

10.3390/vaccines9101107 ◽

2021 ◽

Vol 9 (10) ◽

pp. 1107

Author(s):

Anna Franca Cavaliere ◽

Simona Zaami ◽

Marta Pallottini ◽

Federica Perelli ◽

Annalisa Vidiri ◽

...

Keyword(s):

Prenatal Care ◽

Pregnant Women ◽

Vaccination Campaign ◽

First Trimester ◽

Communicable Diseases ◽

Vaccine Hesitancy ◽

Third Trimester ◽

Maternal Immunization ◽

First Trimester Of Pregnancy ◽

In Pregnancy

Background: Tdap and flu immunization in pregnancy has been proven to be both effective and safe. Despite this, the vaccination rate in pregnant women is low in Italy. The COVID-19 pandemic has focused the attention of public opinion on communicable diseases, underlining the importance of primary prevention measures such as vaccination. We conducted a survey to investigate the behavior of pregnant women during the COVID-19 pandemic regarding maternal immunization to identify the reasons for vaccine hesitancy in order to overcome them. The new challenge is COVID-19 vaccination in pregnancy, and preliminary data show hesitancy towards it. Our analysis may be useful to improve immunization in the pregnant population, including through the COVID-19 vaccine. Methods: A targeted survey was performed in Italy including 520 women who experienced in the first trimester of pregnancy, prior to the novel coronavirus spread, the 2019–2020 influenza vaccination campaign and the Tdap vaccine recommendation in the third trimester during the COVID pandemic. They represent a unique model to investigate if the new coronavirus outbreak might have changed attitudes towards vaccination in pregnancy in the same patients. Data were collected from a self-completed paper questionnaire. Descriptive statistics were calculated and percentages were compared using the chi-2 test or Fisher’s exact test. Results: We obtained data from 195 of the 520 women who gave birth during the inclusion period; 325 cases declined to participate in the survey. A total of 8.7% (17 cases) performed flu vaccination in the first trimester of pregnancy (pre-COVID era), 50.8% (99 cases) accepted Tdap immunization during their third trimester of gestation (COVID-19 pandemic) and 6.7% (13 cases) received both vaccines during pregnancy. For both the flu and Tdap shots, pregnant patients were more likely to accept the vaccines if they were recommended by a healthcare provider, whereas the main reason not to be vaccinated was the lack of such a recommendation. Conclusions: Our survey shows that the COVID-19 experience, which has raised awareness as to the role of vaccines in preventable diseases, may positively change attitudes toward immunization in pregnancy. Vaccination must be recommended to all pregnant women and organized during routine prenatal care as an important element for the prevention of communicable diseases. Vaccination hesitancy can be minimized through consistent recommendation to all pregnant women offered by obstetric staff during routine prenatal care. This approach is likely to be effective in terms of building trust in flu and Tdpa immunization among pregnant women, as well as to avoid unjustified hesitancy towards the more recent COVID-19 vaccines.

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Immunization in Pregnancy

Public Health ◽

10.1093/obo/9780199756797-0195 ◽

2019 ◽

Author(s):

Varun K. Phadke

Keyword(s):

Pregnant Women ◽

World Health ◽

Protective Effects ◽

Substantial Impact ◽

Vaccine Preventable Diseases ◽

Maternal Immunization ◽

Young Infants ◽

Syncytial Virus ◽

Expanded Program On Immunization ◽

In Pregnancy

Routine childhood immunization has had a substantial impact on pediatric morbidity and mortality globally. However, owing to suboptimal immune responses to vaccines in very young infants, immunization schedules do not begin until infants are at least two months of age (six weeks of age in countries following the World Health Organization’s (WHO) Expanded Program on Immunization [EPI] schedule). Thus, the youngest infants are unable to benefit from the protective effects of routine vaccines. These infants are also the most vulnerable to complications and death due to many vaccine-preventable diseases. Immunization in pregnancy, often referred to as maternal immunization, has emerged as a promising strategy to address this gap. This immunization strategy takes advantage of the normal transplacental transfer of antibodies from mother to fetus during pregnancy (as well as to the infant through breast milk in the postpartum period) to confer passive immunity to young infants through maternally derived vaccine-induced antibodies. In addition, because pregnant women are at higher risk of complications due to certain infectious diseases that are or may be vaccine-preventable, maternal immunization is increasingly recognized as an essential component of routine antenatal care. Widespread programmatic use of immunization in pregnancy began with the inclusion of maternal tetanus toxoid vaccination in the WHO’s Expanded Program on Immunization in the 1970s. Since then, immunization of pregnant women against influenza and pertussis has now also become routine in many countries, and vaccines against other important pathogens in infancy (e.g., respiratory syncytial virus and group B Streptococcus) that may be prioritized for use in pregnancy are in development. Indeed, with increased recognition of the substantial burden of potentially vaccine-preventable diseases in pregnant women and infants, the potential public health benefits of maternal immunization could be enormous. Maternal immunization has thus grown into a field at the leading edge of vaccinology. This article highlights research that has examined a broad range of questions pertaining to immunization in pregnancy, including the immunology of pregnancy; the epidemiology of vaccine-preventable diseases in pregnant women and young infants; the clinical efficacy and safety of vaccines currently used in pregnancy; issues related to vaccine acceptance, policy, and implementation; and maternal vaccines on the horizon.

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The Protective Role of Maternal Immunization in Early Life

Frontiers in Pediatrics ◽

10.3389/fped.2021.638871 ◽

2021 ◽

Vol 9 ◽

Author(s):

Bianca Cinicola ◽

Maria Giulia Conti ◽

Gianluca Terrin ◽

Mayla Sgrulletti ◽

Reem Elfeky ◽

...

Keyword(s):

Immune System ◽

Early Life ◽

Optimal Timing ◽

Fetal Life ◽

T Helper ◽

T Helper 1 ◽

Maternal Immunization ◽

Maternal Vaccination ◽

On The Road ◽

In Pregnancy

With birth, the newborn is transferred from a quasi-sterile environment to the outside world. At this time, the neonatal immune system is inexperienced and continuously subject to a process of development as it encounters different antigenic stimuli after birth. It is initially characterized by a bias toward T helper 2 phenotype, reduced T helper 1, and cytotoxic responses to microbial stimuli, low levels of memory, and effector T and B cells and a high production of suppressive T regulatory cells. The aim of this setting, during fetal life, is to maintain an anti-inflammatory state and immune-tolerance. Maternal antibodies are transferred during pregnancy through the placenta and, in the first weeks of life of the newborn, they represent a powerful tool for protection. Thus, optimization of vaccination in pregnancy represents an important strategy to reduce the burden of neonatal infections and sepsis. Beneficial effects of maternal immunization are universally recognized, although the optimal timing of vaccination in pregnancy remains to be defined. Interestingly, the dynamic exchange that takes place at the fetal-maternal interface allows the transfer not only of antibodies, but also of maternal antigen presenting cells, probably in order to stimulate the developing fetal immune system in a harmless way. There are still controversial effects related to maternal immunization including the so called “immunology blunting,” i.e., a dampened antibody production following infant's vaccination in those infants who received placentally transferred maternal immunity. However, clinical relevance of this phenomenon is still not clear. This review will provide an overview of the evolution of the immune system in early life and discuss the benefits of maternal vaccination. Current maternal vaccination policies and their rationale will be summarized on the road to promising approaches to enhance immunity in the neonate.

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