Global Perspectives on Immunization During Pregnancy and Priorities for Future Research and Development: An International Consensus Statement

Predictors of maternal pertussis vaccination acceptance among pregnant women in Norway

Maternal vaccination against pertussis is safe and provides effective protection against pertussis for the newborn, but the vaccine coverage rate remains generally low. Norway is currently planning for introduction of routine maternal pertussis vaccination. To assess maternal pertussis vaccination acceptance among pregnant Norwegian women, we surveyed women at 20-40 weeks gestation in 2019. Among the 1,148 pregnant women participating in this cross-sectional study, 73.8% reported they would accept pertussis vaccination during pregnancy if it was recommended, 6.9% would not accept and 19.2% were undecided. Predictors for low likelihood of accepting pertussis vaccination during pregnancy included low confidence in health authorities and in maternal pertussis vaccination safety and effectiveness, low awareness and adherence to influenza vaccination during pregnancy, and low awareness of pertussis vaccination. The major reasons reported for not accepting or being undecided about maternal pertussis vaccination were lack of information on vaccine safety for both mother and child. Most women reported that they would consult their general practitioner or a midwife for information if they were offered maternal pertussis vaccination. General practitioners and midwives were also regarded as the most trustworthy sources of information if the women were in doubt about accepting vaccination. We conclude that information addressing safety concerns and raising awareness about maternal pertussis vaccination could increase acceptance of maternal pertussis vaccination. Our findings highlight the pivotal role of the antenatal and primary health care services in providing such information to pregnant women.

The current state of pertussis vaccination in pregnancy around the world, with recommendations for improved care: Consensus statements from the Global Pertussis Initiative

Bordetella pertussis, which causes a respiratory disease known as pertussis ("whooping cough") remains an important global challenge, with the incidence in pertussis cases increasing in recent years. Newborns and infants are at increased risk for severe morbidity and mortality from this bacterium. Vaccination in pregnancy has become an important strategy to both passively transfer immunity as well as prevent infection in pregnant persons, who are a major source of newborn infection, thus attempting to decrease the impact of this serious disease. It is considered safe for the pregnant person, the developing fetus, and the infant, and during the first 3 months of life it has been shown to be highly effective in preventing pertussis. There are a variety of strategies, recommendations, and adherence rates associated with pertussis vaccination in pregnancy around the world. We summarize the 2021 Global Pertussis Initiative Annual Meeting that reviewed the current global status of pertussis vaccination in pregnancy and remaining medical and scientific questions, with a focus on vaccination challenges and strategies for obstetric and gynecologic healthcare providers.

Vaccination: Adherence and Hesitancy among Pregnant Women for COVID-19, Pertussis, and Influenza Vaccines

In the realm of antenatal care, vaccinations serve as a cornerstone, crucial for safeguarding the health of both the mother and the fetus, while also extending protection to the newborn against communicable diseases. Nevertheless, vaccine adherence among pregnant women remains very low. The aim of our study was to evaluate the uptake of vaccines (influence, pertussis, and COVID-19) among women during pregnancy and to understand pregnant women's knowledge of vaccines and the diseases they protect against. The purpose was to investigate the reasons why pregnant women chose not to be vaccinated and to develop effective strategies for informing them about the importance of vaccination for both maternal and fetal safety. A prospective observational study was conducted in the Department of Obstetrics and Gynaecology, "Ospedale Santa Maria della Misericordia" in Udine, from 1 December 2021 to 30 June 2022. During this period, a self-completed paper questionnaire was administered to women at the end of pregnancy or during the puerperium. A total of 161 questionnaires were collected. Higher educational level was found to be significantly associated with influenza vaccination uptake (p = 0.037, OR = 2.18, 95% CI 1.05-4.51). Similarly, for pertussis vaccination, adherence was mainly associated with higher educational level (p = 0.014, OR = 2.83, 95% CI 1.24-6.47), but also with Italian nationality (p = 0.003, OR = 3.36, 95% CI 1.56-8.43) and pregnancy attended by a midwife or private gynecologist (p = 0.028, OR = 0.39, 95% CI 0.17-0.90). Regarding the COVID-19 vaccine, the only factor positively influencing uptake was Italian nationality (p = 0.044, OR = 2.66, 95% CI 1.03-6.91). Women's fear that vaccines would endanger the fetus appeared to be the most important reason for refusing vaccinations. Simultaneously, patients also exhibited a desire to receive more information about maternal vaccination, particularly from their general physician or gynecologist. For this reason, it is imperative to enhance maternal vaccination counselling, making it a routine step in prenatal care from the first antenatal visit until the postpartum period.

Interventional study to improve pertussis and influenza vaccination uptake in pregnant women

OBJECTIVES

Pertussis and influenza are endemic infections and associated with relevant morbidity and mortality in newborns and young infants. The Swiss Federal Office of Public Health has recommended influenza vaccination since 2011 and pertussis vaccination in pregnancy (ViP) since 2013 and expanded to repetition in each pregnancy since 2017. ViP is safe and effective in preventing severe diseases, but implementation is a challenge. We hypothesized that the proportion of women receiving ViP is persistently low despite existing national recommendations. Our primary objective was to compare the proportion of pertussis and influenza vaccine recommendations for and its acceptance by pregnant women before and after an information campaign tailored to obstetricians. Secondly, we aimed to identify reasons for missing or declining ViP.

STUDY DESIGN

We conducted a prospective, single-center, single-arm implementation study in the maternity ward at the University Women's Hospital Basel. We performed standardized interviews with women hospitalized for postpartum care before (October to December 2019, Phase 1, n = 262) and after an information campaign (October to December 2020, Phase 2, n = 233) and compared categorical variables using chi-squared or Fisher's exact test and continuous variables using Whitney Mann U test.

RESULTS

We found no significant differences in the proportion of recommendation for pertussis ViP (80 % vs. 84 %, p = 0.25) and implementation (76 % vs. 78 %, p = 0.63) between Phase 1 and 2. Main reasons for missing or declining vaccinations were lack of recommendation (62.8 %) and safety concerns regarding the unborn child (17.7 %). In contrast, the proportion of recommendation for influenza ViP (45 % vs. 63 %, p < 0.001) and implementation (29 % vs. 43 %, p < 0.001) increased significantly.

CONCLUSION

Proactive recommendations by obstetricians play a key role in the implementation of ViP but is still insufficient in our setting. We believe that future efforts should aim to explore possible hurdles that impede recommendations by obstetricians for ViP. The focus should be on the needs and experiences of obstetricians in private practice, but also other health care professionals involved in care of pregnant women. Local campaigns do not seem effective enough, therefore national campaigns with new strategies are desirable.

Burden of Respiratory Syncytial Virus-Associated Acute Respiratory Infections During Pregnancy

BACKGROUND

With the licensure of maternal respiratory syncytial virus (RSV) vaccines in Europe and the United States, data are needed to better characterize the burden of RSV-associated acute respiratory infections (ARI) in pregnancy. The current study aimed to determine among pregnant individuals the proportion of ARI testing positive for RSV and the RSV incidence rate, RSV-associated hospitalizations, deaths, and perinatal outcomes.

METHODS

We conducted a systematic review, following PRISMA 2020 guidelines, using 5 databases (Medline, Embase, Global Health, Web of Science, and Global Index Medicus), and including additional unpublished data. Pregnant individuals with ARI who had respiratory samples tested for RSV were included. We used a random-effects meta-analysis to generate overall proportions and rate estimates across studies.

RESULTS

Eleven studies with pregnant individuals recruited between 2010 and 2022 were identified, most of which recruited pregnant individuals in community, inpatient and outpatient settings. Among 8126 pregnant individuals, the proportion with ARI that tested positive for RSV ranged from 0.9% to 10.7%, with a meta-estimate of 3.4% (95% confidence interval [CI], 1.9%-54%). The pooled incidence rate of RSV among pregnant individuals was 26.0 (95% CI, 15.8-36.2) per 1000 person-years. RSV hospitalization rates reported in 2 studies were 2.4 and 3.0 per 1000 person-years. In 5 studies that ascertained RSV-associated deaths among 4708 pregnant individuals, no deaths were reported. Three studies comparing RSV-positive and RSV-negative pregnant individuals found no difference in the odds of miscarriage, stillbirth, low birth weight, and small size for gestational age. RSV-positive pregnant individuals had higher odds of preterm delivery (odds ratio, 3.6 [95% CI, 1.3-10.3]).

CONCLUSIONS

Data on RSV-associated hospitalization rates are limited, but available estimates are lower than those reported in older adults and young children. As countries debate whether to include RSV vaccines in maternal vaccination programs, which are primarily intended to protect infants, this information could be useful in shaping vaccine policy decisions.

Prenatal Maternal Immunization for Infant Protection: A Review of the Vaccines Recommended, Infant Immunity and Future Research Directions

Prenatal maternal immunization is an effective tool to protect mothers and infants from poor health outcomes due to infectious diseases. We provide an overview of the rationale for the use of prenatal vaccines, discuss the immunologic environment of the maternal-fetal interface including the impact of maternal vaccines prenatally and subsequently on the infant's immune response, and review vaccines currently recommended in pregnancy and landscape for the future of maternal vaccination. This review aims to provide an understanding of the recent history and progress made in the field and highlight the importance of continued research and development into new vaccines for pregnant populations.

Maternal pertussis immunization and the blunting of routine vaccine effectiveness: a meta-analysis and modeling study

A key goal of pertussis control is to protect infants too young to be vaccinated, the age group most vulnerable to this highly contagious respiratory infection. In the last decade, maternal immunization has been deployed in many countries, successfully reducing pertussis in this age group. Because of immunological blunting, however, this strategy may erode the effectiveness of primary vaccination at later ages. Here, we systematically reviewed the literature on the relative risk (RR) of pertussis after primary immunization of infants born to vaccinated vs. unvaccinated mothers. The four studies identified had ≤6 years of follow-up and large statistical uncertainty (meta-analysis weighted mean RR: 0.71, 95% CI: 0.38-1.32). To interpret this evidence, we designed a new mathematical model with explicit blunting mechanisms and evaluated maternal immunization's short- and long-term impact on pertussis transmission dynamics. We show that transient dynamics can mask blunting for at least a decade after rolling out maternal immunization. Hence, the current epidemiological evidence may be insufficient to rule out modest reductions in the effectiveness of primary vaccination. Irrespective of this potential collateral cost, we predict that maternal immunization will remain effective at protecting unvaccinated newborns, supporting current public health recommendations.

Characteristics of Respiratory Syncytial Virus Infections in Children in the Post-COVID Seasons: A Northern Italy Hospital Experience

BACKGROUND

Public health measures for COVID-19 mitigation influenced the circulation of Respiratory Syncytial Virus (RSV) during the 2020-2021 winter season. In the following autumn, an unprecedented resurgence of RSV occurred. Our study monitored RSV pediatric infections one and two years after the relaxation of containment measures for the COVID-19 pandemic.

METHODS

We analyzed diagnostic molecular data for SARS-CoV-2, flu, and RSV infections and clinical data from children with respiratory symptoms referring to our hospital during the 2021-2022 and 2022-2023 seasons.

RESULTS

In the 2021-2022 season, the number of RSV-affected children was very high, especially for babies <1 year. The outbreak appeared in a shorter interval of time, with a high clinical severity. In the 2022-23 season, a reduced number of infected pediatric patients were detected, with a similar hospitalization rate (46% vs. 40%), and RSV accounted for 12% of the infections. Coinfections were observed in age <2 years. In RSV patients, symptoms were similar across the two seasons.

CONCLUSIONS

The clinical presentation of RSV in the two post-COVID seasons suggests that the pathophysiology of the virus did not change across these two years. Further studies are needed to continuously monitor RSV to support an effective prevention strategy.

Factors Associated With Influenza Vaccination During Pregnancy: A Real-World Evidence-Based Study

Pregnant women are at increased risk of influenza-related complications. However, the rate of influenza vaccination among pregnant women in Taiwan is low. By analyzing real-world data in this study, we investigated the factors associated with influenza vaccination during pregnancy in Taiwan. This study was a cross-sectional study. We collected real-world data from 2 databases in Taiwan: the Birth Certificate Database and the National Health Insurance Research Database. The study population was pregnant between October 2014 and December 2016 in Taiwan. The multivariate logistic regression was performed to identify factors associated with influenza vaccination, including maternal sociodemographics, trimester, comorbidities, and health-care utilization. The vaccination rate of among pregnant women was 8.2%. Factors significantly associated with a high likelihood of influenza vaccination were age between 30 and 34 years (odds ratio [OR]: 1.14; 95% confidence interval [CI]: 1.10-1.19), second trimester (OR: 1.80; 95% CI: 1.75-1.85), income equal to or exceeding NT$ 38 201 (OR: 1.92; 95% CI: 1.86-1.99), hypertension (OR: 1.16; 95% CI: 1.05-1.29), cardiovascular disease (OR: 1.29; 95% CI: 1.17-1.42), autoimmune disease (OR: 1.47; 95% CI: 1.38-1.58), and chronic pulmonary disease (OR: 1.24; 95% CI: 1.18-1.31). A low level of urbanization, at least 1 hospitalization in the previous year, and the presence of pregnancy complications (eg, gestational diabetes, preeclampsia, and placenta previa) were associated with a lower likelihood rate of influenza vaccination. The influenza vaccination rate among pregnant women in Taiwan was low. Age, gestational age, income level, urbanization level, hypertension, cardiovascular disease, autoimmune disease, chronic pulmonary disease, and pregnancy complications may be associated with influenza vaccination among pregnant women.

Vaccine safety surveillance in Kenya using GAIA standards: A feasibility assessment of existing national and subnational research and program systems

BACKGROUND

Active surveillance systems for monitoring vaccine safety among pregnant women address some of the limitations of a current passive surveillance approach utilized in low- and middle-income countries (LMIC). However, few active surveillance systems in LMIC exist. Our study assessed the feasibility of utilizing three existing data collection systems in Kenya for active surveillance of maternal immunization and to assess the applicability of Global Alignment of Immunization Safety Assessment in pregnancy (GAIA) case definitions that were initially developed for clinical trials within these systems.

METHODS

We assessed applicability of GAIA case definition for maternal Tetanus Toxoid exposure, stillbirth, low birth weight, small for gestational age, Neonatal Invasive Blood Stream Infection (NIBSI), prematurity and neonatal death in two routine web-based health information systems (Kenya EMR and DHIS-2), and a web-based population-based pregnancy research platform (ANCOV1) in Kenya.

RESULTS

All three HIS were capable of reporting selected outcomes to varying degrees of GAIA certainty. The ANCOV platform was the most robust in collecting and collating clinical data for effective maternal pharmacovigilance. The utilization of facility- and district-aggregated data limits the usefulness of DHIS-2 in pharmacovigilance as currently operationalized. While the Kenya EMR contained individual level data and meets the key considerations for effective pharmacovigilance, it was used primarily for HIV care and treatment records in a small proportion of health facilities and would require additional resources to expand to all antenatal care facilities and to link maternal and infant records.

DISCUSSION

Population-based research studies may offer a responsive short-term option for implementing maternal vaccine pharmacovigilance in LMICs. However, the foundation exists for long-term capacity building within the national health electronic data systems to provide this critical service as well as ensure participation of the country in international studies on maternal vaccine safety.

Safety and Clinical Benefits of Adacel® and Adacel®-Polio Vaccination in Pregnancy: A Structured Literature Review

Vaccination in pregnancy using a tetanus toxoid, reduced dose diphtheria toxoid, and reduced dose acellular pertussis (Tdap) vaccine is important for prevention of severe pertussis disease in young infants. The objectives of this systematic literature review were to search for original research studies evaluating the vaccine effectiveness, immunogenicity, and safety of Adacel®/Adacel-Polio® used during pregnancy to prevent pertussis disease in young infants. Medical databases used included EMBASE, BIOSIS Previews, and Chemical Abstracts, with search terms related to pregnancy, vaccines/immunization, safety, pertussis, effectiveness/efficacy, and immune response; other potentially eligible reports were included where applicable. Search results were restricted to literature published from 1 January 1995 to 26 July 2021. A total of 2021 articles and 4 other reports were identified for primary review. A total of 49 publications qualified for inclusion after primary and secondary reviews. Effectiveness studies of Adacel or Adacel-Polio given in pregnancy consistently showed high levels of protection from pertussis disease in the newborn (vaccine effectiveness: 91-93%). In immunogenicity studies, the response in pregnant women was consistent with that of non-pregnant women. Infants of mothers vaccinated with Adacel or Adacel-Polio in pregnancy had higher anti-pertussis antibody levels at birth and at 2 months of age compared to infants born to women vaccinated with comparator vaccines, placebo, or those not vaccinated during pregnancy. There was evidence of a slightly decreased response to primary pertussis vaccination in infants of mothers vaccinated with Adacel or Adacel-Polio, but this was not thought to be clinically significant. In safety studies, Adacel or Adacel-Polio vaccination was well tolerated by pregnant woman and not associated with pregnancy, postpartum, or neonatal complications. In conclusion, Adacel or Adacel-Polio vaccination in pregnancy is highly effective in protecting young infants from pertussis disease, with a favorable safety profile for both pregnant women and their infants.

Vaccine Hesitancy Phenomenon Evolution during Pregnancy over High-Risk Epidemiological Periods-"Repetitio Est Mater Studiorum"

(1) Background: The recent epidemiological events were high-stress level generators for humanity, particularly for pregnant women, influencing their attitude, behavior, and decisions regarding vaccination during pregnancy or regarding their future child. The aim of this study was to analyze the anti-pertussis vaccination decision-shaping factors in pregnant women during two epidemiological periods: the measles epidemic and the COVID-19 pandemic. (2) Methods: Two groups of pregnant women were invited to be part of a medical education program, having as the main theme the infectious disease risks and their prevention through vaccination. Before launching the program, participants received a 12-item questionnaire. From a total number of 362 pregnant women enrolled in the study, 182 participated in 2019, and 180 participated in 2022. (3) Results: The socio-demographic data revealed that the age of pregnant women participating in medical education programs increased in 2022 by 1.7 years (p < 0.01). In vitro fertilization was reported in a significantly higher proportion (20% in 2022 vs 9.8% in 2019, p < 0.01). Participation in community-initiated educational programs almost doubled during the pandemic time from 18.7% in 2019 to 33.9% in 2022 (p < 0.01). Pertussis vaccine acceptancy (VA) dropped from 85% in 2019 to 44.4% in 2022 (p < 0.01) (4) Conclusions: In this study, we reported fast-growing vaccine hesitancy and severe declared vaccine reluctance. The results of this complex long-term study, which evaluated pregnant women over several years, showed a five-fold increase in the percentage of pregnant women who disagreed with personal pertussis vaccination. This draws attention to the risks of pertussis epidemic outbreaks in pregnant women and their future infants in the first couple of months of life before the initiation of vaccination.

Impact of maternal whole-cell or acellular pertussis primary immunization on neonatal immune response

With the introduction of pertussis immunization for pregnant women in many countries, there has been renewed interest in the impact of whole-cell pertussis vaccine (wP) versus acellular vaccine (aP) on disease control, particularly regarding the best approach for priming. To gather evidence on this topic, we analyzed the impact of aP or wP priming on aP vaccination during pregnancy (aPpreg) in mice. Two-mother vaccination schemes were employed (wP-wP-aPpreg and aP-aP-aPpreg), and the immune response in the mothers and their offspring, as well as the protection of the offspring against Bordetella pertussis challenge, were assessed. Pertussis toxin (PTx)-specific IgG responses were detected in mothers after both the second and third doses, with higher titers after the third dose, regardless of the vaccination schedule. However, a significant reduction in PTx-IgG levels was observed after 22 weeks post aPpreg immunization in mothers with the aP-aP-aPpreg scheme but not in the wP-wP-aPpreg immunized mothers. The aP-aP-aPpreg schedule triggered a murine antibody response mainly to a Th2-profile, while wP-wP-aPpreg induced a Th1/Th2 mixed profile. Both immunization schemes administered to the mothers protected the offspring against pertussis, but the wP-wP-aPpreg vaccination conferred offspring protection in all pregnancies at least up to 20 weeks after receiving the aPpreg-dose. In contrast, the immunity induced by aP-aP-aPpreg began to decline in births that occurred 18 weeks after receiving the aPpreg dose. For the aP-aP-aPpreg scheme, pups born from gestations furthest from aPpreg (+22 weeks) had lower PTx-specific IgG levels than those born closer to the application of the dose during pregnancy. In contrast, for pups born to wP-wP-aPpreg vaccinated mothers, the PTx-specific IgG levels were maintained over time, even for those born at the longest time studied (+22 weeks). It is noteworthy that only the pups born from mothers with aP-aP-aPpreg and receiving a neonatal dose of either aP or wP were more susceptible to B. pertussis infection than mice with only maternal immunity, suggesting interference with the induced immunity (p<0.05). However, it should be noted that mice with maternal immunity, whether vaccinated or not with neonatal doses, are better protected against colonization with B. pertussis than mice without maternal immunity but vaccinated with aP or wP.

Impact of pregnancy on polyfunctional IgG and memory B cell responses to Tdap immunization

BACKGROUND

Maternal pertussis immunization using Tdap vaccine is recommended in many countries to protect newborns from severe post-natal infection. Immunological changes during pregnancy may influence the response to vaccines. The quality of IgG and memory B cell responses to Tdap immunization in pregnant women has not yet been described.

METHODS

The impact of pregnancy on the response to Tdap vaccination was assessed by comparing humoral immune responses in 42 pregnant and 39 non-pregnant women. The levels of serum pertussis antigens and tetanus toxoid-specific IgG, IgG subclasses, IgG Fc-mediated effector functions, as well as memory B cell frequencies were assessed before and at several time points after vaccination.

RESULTS

Tdap immunization induced similar levels of pertussis and tetanus-specific IgG and IgG subclasses in pregnant and non-pregnant women. Pregnant women produced IgG promoting complement deposition, and neutrophils and macrophages phagocytosis at levels comparable to non-pregnant women. They were also able to expand pertussis and tetanus-specific memory B cells at similar frequencies as non-pregnant women, suggesting equivalent "boostability". Higher levels of vaccine-specific IgG, IgG subclasses, and IgG Fc-mediated effector functions were detected in cord blood as compared to maternal blood, indicating efficient transport across the placenta.

CONCLUSIONS

This study demonstrates that pregnancy does not affect the quality of effector IgG and memory B cell responses to Tdap immunization and that polyfunctional IgG are efficiently transferred across the placenta.

REGISTRY'S URL AND THE TRIAL'S REGISTRATION NUMBER

ClinicalTrials.Gov (NCT03519373).

Vaccine hesitancy in pregnant Women: A narrative review

Pregnant women are often at higher risk for morbidity and mortality due to contracting vaccine-preventable diseases that result in adverse pregnancy outcomes such as spontaneous abortion, preterm births, and congenital fetal defects. For example, health care provider recommendation is correlated with maternal acceptance of influenza vaccination, however, up to 33 % of pregnant women remain unvaccinated irrespective of provider recommendation. Vaccine hesitancy is a multifactorial problem that both the medical and public health systems need to address synergistically. Vaccine education should incorporate balanced perspectives to deliver vaccine education. This narrative review addresses four questions: 1) what are the primary concerns of pregnant women that lead them to be hesitant about receiving vaccinations; 2) to what extent does the source (e.g. provider, friend, family) of vaccine advice and information influence a pregnant person's decision to accept a vaccine; 3) how does the delivery method of vaccine education influence their decision; 4) how can categorizing patients into four distinct groups based on their opinions and behavior regarding vaccines be used to improve provider-patient communication and increase vaccine acceptance. Results from the literature show that the three most common reasons for vaccine hesitancy include: i.) fear of side effects or adverse events; ii.) lack of confidence in vaccine safety; iii.) low perception of being at high risk of infection during pregnancy and/or not having previously received the vaccination when not pregnant. We conclude that vaccine hesitancy is dynamic therefore people do not always hold a static level of vaccine hesitancy. People may move between a continuum of vaccine hesitancy for a multifactorial reasons. A framework, characterized by levels of vaccine hesitancy before and during pregnancy, was constructed to help providers find balance between promoting individual health and public health while providing vaccine education.

Bivalent Prefusion F Vaccine in Pregnancy to Prevent RSV Illness in Infants

BACKGROUND

Whether vaccination during pregnancy could reduce the burden of respiratory syncytial virus (RSV)-associated lower respiratory tract illness in newborns and infants is uncertain.

METHODS

In this phase 3, double-blind trial conducted in 18 countries, we randomly assigned, in a 1:1 ratio, pregnant women at 24 through 36 weeks' gestation to receive a single intramuscular injection of 120 μg of a bivalent RSV prefusion F protein-based (RSVpreF) vaccine or placebo. The two primary efficacy end points were medically attended severe RSV-associated lower respiratory tract illness and medically attended RSV-associated lower respiratory tract illness in infants within 90, 120, 150, and 180 days after birth. A lower boundary of the confidence interval for vaccine efficacy (99.5% confidence interval [CI] at 90 days; 97.58% CI at later intervals) greater than 20% was considered to meet the success criterion for vaccine efficacy with respect to the primary end points.

RESULTS

At this prespecified interim analysis, the success criterion for vaccine efficacy was met with respect to one primary end point. Overall, 3682 maternal participants received vaccine and 3676 received placebo; 3570 and 3558 infants, respectively, were evaluated. Medically attended severe lower respiratory tract illness occurred within 90 days after birth in 6 infants of women in the vaccine group and 33 infants of women in the placebo group (vaccine efficacy, 81.8%; 99.5% CI, 40.6 to 96.3); 19 cases and 62 cases, respectively, occurred within 180 days after birth (vaccine efficacy, 69.4%; 97.58% CI, 44.3 to 84.1). Medically attended RSV-associated lower respiratory tract illness occurred within 90 days after birth in 24 infants of women in the vaccine group and 56 infants of women in the placebo group (vaccine efficacy, 57.1%; 99.5% CI, 14.7 to 79.8); these results did not meet the statistical success criterion. No safety signals were detected in maternal participants or in infants and toddlers up to 24 months of age. The incidences of adverse events reported within 1 month after injection or within 1 month after birth were similar in the vaccine group (13.8% of women and 37.1% of infants) and the placebo group (13.1% and 34.5%, respectively).

CONCLUSIONS

RSVpreF vaccine administered during pregnancy was effective against medically attended severe RSV-associated lower respiratory tract illness in infants, and no safety concerns were identified. (Funded by Pfizer; MATISSE ClinicalTrials.gov number, NCT04424316.).

Prenatal tetanus-diphtheria-acellular pertussis vaccine effectiveness at preventing infant pertussis

OBJECTIVE

To evaluate the effectiveness of the tetanus, diphtheria, and acellular pertussis (Tdap) vaccine containing five pertussis components (Tdap5; Adacel®, Sanofi) when given during pregnancy at preventing pertussis in infants less than 2 months of age.

METHODS

The US Centers for Disease Control and Prevention (CDC), in collaboration with the Emerging Infections Program (EIP) Network, undertook a case-control study evaluating the effectiveness of Tdap vaccination in pregnancy against pertussis in infants less than 2 months of age based on data collected by the EIP Network from 2011 through 2014. The dataset from the CDC/EIP Network study was used to conduct this product-specific vaccine effectiveness analysis of Tdap5 vaccination in pregnancy to prevent disease in young infants. The main outcome of interest was vaccine effectiveness in infants whose pregnant parents were vaccinated with Tdap5 between 27 and 36 weeks' gestation, in accordance with the ideal timing for Tdap vaccination in pregnancy recommended by the US Advisory Committee on Immunization Practices. Odd ratios (ORs) and 95 % confidence intervals (CIs) were estimated using conditional logistic regression, and vaccine effectiveness was calculated as (1-OR) × 100 %.

RESULTS

There were 160 infant pertussis cases and 302 matched controls included in this Tdap5-specific study. Tdap5 effectiveness in preventing pertussis in infants whose pregnant parents were vaccinated between 27 and 36 weeks' gestation was 92.5 % (95 % CI, 38.5 %-99.1 %). Effectiveness of Tdap5 against pertussis-related hospitalization in infants whose pregnant parents were vaccinated between 27 and 36 weeks' gestation could not be calculated due to lack of discordance among matched cases and controls. Vaccination of the parents after pregnancy or less than 14 days before delivery did not protect infants from pertussis.

CONCLUSIONS

Tdap5 vaccination in pregnancy between 27 and 36 weeks' gestation is highly effective at protecting young infants from pertussis.

STUDY REGISTRATION

ClinicalTrials.gov, NCT05040802.

Metagenomics next-generation sequencing assists in the diagnosis of infant pertussis encephalopathy: A case report

RATIONALE

Pertussis is an acute respiratory infection that often occurs in the pediatric population, especially in infants under 3 months old. Bordetella pertussis is the causative agent of pertussis, which can lead to pneumonia, encephalopathy, and pulmonary hypertension, causing death in severe cases. Therefore, an accurate and comprehensive diagnosis of the pathogen is essential for effective treatment.

PATIENT CONCERNS

We report a case of 2-month-old male infant admitted to the pediatric intensive care unit of West China Second University due to hoarse cough for 7 days, accompanied by a crowing-like echo, fever and listlessness, occasional nonprojectile vomiting with anorexia, shortness of breath, accelerated heart rate, cyanosis of the lips, and convulsions. B pertussis was identified by metagenomic next-generation sequencing in blood and cerebrospinal fluid and polymerase chain reaction assay using blood.

DIAGNOSES

The infant was diagnosed with pertussis.

INTERVENTIONS

Intravenous infusion of erythromycin (50 mg/kg/d) for anti-infection and dexamethasone for alleviating intracranial inflammatory reaction were given.

OUTCOMES

The patient was eventually recovered and discharged.

LESSONS

This case report emphasized the importance of metagenomic next-generation sequencing using cerebrospinal fluid and blood for early diagnosis of pertussis-associated encephalopathy.

The perinatal health challenges of emerging and re-emerging infectious diseases: A narrative review

The world has seen numerous infectious disease outbreaks in the past decade. In many cases these outbreaks have had considerable perinatal health consequences including increased risk of preterm delivery (e.g., influenza, measles, and COVID-19), and the delivery of low birth weight or small for gestational age babies (e.g., influenza, COVID-19). Furthermore, severe perinatal outcomes including perinatal and infant death are a known consequence of multiple infectious diseases (e.g., Ebola virus disease, Zika virus disease, pertussis, and measles). In addition to vaccination during pregnancy (where possible), pregnant women, are provided some level of protection from the adverse effects of infection through community-level application of evidence-based transmission-control methods. This review demonstrates that it takes almost 2 years for the perinatal impacts of an infectious disease outbreak to be reported. However, many infectious disease outbreaks between 2010 and 2020 have no associated pregnancy data reported in the scientific literature, or pregnancy data is reported in the form of case-studies only. This lack of systematic data collection and reporting has a negative impact on our understanding of these diseases and the implications they may have for pregnant women and their unborn infants. Monitoring perinatal health is an essential aspect of national and global healthcare strategies as perinatal life has a critical impact on early life mortality as well as possible effects on later life health. The unpredictable nature of emerging infections and the potential for adverse perinatal outcomes necessitate that we thoroughly assess pregnancy and perinatal health implications of disease outbreaks and their public health interventions in tandem with outbreak response efforts. Disease surveillance programs should incorporate perinatal health monitoring and health systems around the world should endeavor to continuously collect perinatal health data in order to quickly update pregnancy care protocols as needed.

Research priorities for maternal and perinatal health clinical trials and methods used to identify them: A systematic review

OBJECTIVE

Research prioritisation helps to target research resources to the most pressing health and healthcare needs of a population. This systematic review aimed to report research priorities in maternal and perinatal health and to assess the methods that were used to identify them.

METHODS

A systematic review was undertaken. Projects that aimed to identify research priorities that were considered to be amenable to clinical trials research were eligible for inclusion. The search, limited to the last decade and publications in English, included MEDLINE, EMBASE, CINHAL, relevant Cochrane priority lists, Cochrane Priority Setting Methods Group homepage, James Lind Alliance homepage, Joanna Brigg's register, PROSPERO register, reference lists of all included articles, grey literature, and the websites of relevant professional bodies, until 13 October 2020. The methods used for prioritisation were appraised using the Reporting Guideline for Priority Setting of Health Research (REPRISE).

FINDINGS

From the 62 included projects, 757 research priorities of relevance to maternal and perinatal health were identified. The most common priorities related to healthcare systems and services, pregnancy care and complications, and newborn care and complications. The least common priorities related to preconception and postpartum health, maternal mental health, contraception and pregnancy termination, and fetal medicine and surveillance. The most commonly used prioritisation methods were Delphi (20, 32%), Child Health Nutrition Research Initiative (17, 27%) and the James Lind Alliance (10, 16%). The fourteen projects (23%) that reported on at least 80% of the items included in the REPRISE guideline all used an established research prioritisation method.

CONCLUSIONS

There are a large number of diverse research priorities in maternal and perinatal health that are amenable to future clinical trials research. These have been identified by a variety of research prioritisation methods.

Contrast Agents during Pregnancy: Pros and Cons When Really Needed

Many clinical conditions require radiological diagnostic exams based on the emission of different kinds of energy and the use of contrast agents, such as computerized tomography (CT), positron emission tomography (PET), magnetic resonance (MR), ultrasound (US), and X-ray imaging. Pregnant patients who should be submitted for diagnostic examinations with contrast agents represent a group of patients with whom it is necessary to consider both maternal and fetal effects. Radiological examinations use different types of contrast media, the most used and studied are represented by iodinate contrast agents, gadolinium, fluorodeoxyglucose, gastrographin, bariumsulfate, and nanobubbles used in contrast-enhanced ultrasound (CEUS). The present paper reports the available data about each contrast agent and its effect related to the mother and fetus. This review aims to clarify the clinical practices to follow in cases where a radiodiagnostic examination with a contrast medium is indicated to be performed on a pregnant patient.

Vaccination in Pregnancy against Pertussis: A Consensus Statement on Behalf of the Global Pertussis Initiative

Infants are at high risk for severe morbidity and mortality from pertussis disease during early infancy. Vaccination against pertussis in pregnancy has emerged as the ideal strategy to protect infants during these early, vulnerable, first months of life. On 30 November and 1 December 2021, the Global Pertussis Initiative held a meeting that aimed to discuss and review the most up-to-date scientific literature supporting vaccination against pertussis in pregnancy and outstanding scientific questions. Herein, we review the current and historically published literature and summarize the findings as consensus statements on vaccination against pertussis in pregnancy on behalf of the Global Pertussis Initiative.

Protecting the Offspring, the Gift of Maternal Immunization: Current Status and Future Perspectives

Pregnancy is characterized by immunological alterations in pregnant women that permit the growth of a semi-allogenic fetus, resulting in greater susceptibility of childbearing women to infections. Furthermore, due to the immaturity of the immune system of neonates, a protection gap is present in early life, leaving neonates and infants vulnerable to infectious diseases with increased morbidity and mortality. Maternal immunization against influenza, pertussis, and, in the context of the COVID-19 pandemic, SARS-CoV-2 has been implemented in several countries, with beneficial effects on both the mother and the offspring. The main protective mechanism of vaccination during pregnancy is transplacental transfer of maternal antibodies. However, recent evidence has implied that the fetal immune system may be influenced beyond passive immunity. This review sheds light on the current status of the routinely administered vaccinations during pregnancy, focusing on the impact of maternal immunization on the priming of the fetal immune system and suggesting future perspectives for the optimization of vaccination strategies.

Vaccination in pregnancy: The role of the midwife

Midwives are the front-line workers providing maternity care for women in many countries. The role of the midwife includes providing information about, and recommendations for, maternal vaccination in pregnancy and for the baby in the postnatal period. Vaccinations recommended in pregnancy include those to prevent influenza, pertussis, tetanus and now COVID-19. Vaccinations for the newborn baby include hepatitis B. Healthcare professionals play an important role in influencing decision-making around vaccination and midwives are key in supporting vaccination uptake. Midwives are strong influencer in women's decisions around vaccination for themselves and their babies. The COVID-19 vaccination programs have shone a light on vaccination in pregnancy especially as SARS-COV-2 infection has significant adverse effects in pregnancy. COVID-19 vaccination has been shown to be safe and effective in pregnancy. Despite this, there is vaccine hesitancy from pregnant women in many countries. Midwives play a unique role in the provision of care to women and families but they need specific support and information regarding vaccination in pregnancy. Targeted education, supportive mentoring and supervision and opportunities to lead innovative ways of ensuring vaccine access is logistically easy and possible are all needed. This Commentary outlines the key vaccinations recommended in pregnancy including COVID-19 vaccination and highlights some strategies to scale-up vaccination programs in pregnancy with a particular focus on the role of midwives.

Pregnancy Status at the Time of Coronavirus Disease 2019 Vaccination and Incidence of Severe Acute Respiratory Syndrome Coronavirus 2 Infection

BACKGROUND

Pregnant women are recommended to receive coronavirus disease 2019 (COVID-19) vaccines; however, relative effectiveness of vaccination by pregnancy status is unclear.

METHODS

We compared the relative effectiveness of messenger RNA (mRNA) COVID-19 vaccines according to whether women received both doses while pregnant (n = 7412), 1 dose while pregnant (n = 3538), both doses while postpartum (n = 1856), or both doses while neither pregnant nor postpartum (n = 6687). We estimated risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection starting 14 days after the second dose using Cox regression, reporting hazard ratios (HRs) and 95% confidence intervals (CIs). Second, we examined relative effectiveness of a third (booster) dose while pregnant compared to outside pregnancy. The major circulating variant during the study period was the Delta variant.

RESULTS

Fifty-four percent of women received 2 doses of the BNT162b2 vaccine, 16% received 2 doses of the mRNA-1273 vaccine, while 30% received 1 dose of both vaccines. Compared to women who received both doses while neither pregnant nor postpartum, the adjusted HR for a positive SARS-CoV-2 polymerase chain reaction test was similar if the woman received both doses while pregnant (1.04 [95% CI, .94-1.17]), 1 dose while pregnant and 1 dose before or after pregnancy (1.03 [95% CI, .93-1.14]), or both doses while postpartum (0.99 [95% CI, .92-1.07]). The findings were similar for BNT162b2 (Pfizer-BioNTech Comirnaty) and mRNA-1273 (Moderna Spikevax), and during Delta- and Omicron-dominant periods. We observed no differences in the relative effectiveness of the booster dose according to pregnancy status.

CONCLUSIONS

We observed similar effectiveness of mRNA vaccines against SARS-CoV-2 infection among women regardless of pregnancy status at the time of vaccination.

Association of COVID-19 Vaccination During Pregnancy With Incidence of SARS-CoV-2 Infection in Infants

IMPORTANCE

Pregnant women are recommended to receive COVID-19 vaccination to reduce risk of severe COVID-19. Whether vaccination during pregnancy also provides passive protection to infants after birth remains unclear.

OBJECTIVE

To determine whether COVID-19 vaccination in pregnancy was associated with reduced risk of COVID-19 in infants up to age 4 months during COVID-19 pandemic periods dominated by Delta and Omicron variants.

DESIGN, SETTING, AND PARTICIPANTS

This nationwide, register-based cohort study included all live-born infants born in Norway between September 1, 2021, and February 28, 2022.

EXPOSURES

Maternal messenger RNA COVID-19 vaccination during second or third trimester compared with no vaccination before or during pregnancy.

MAIN OUTCOMES AND MEASURES

The risk of a positive polymerase chain reaction test result for SARS-CoV-2 during an infant's first 4 months of life by maternal vaccination status during pregnancy with either dose 2 or 3 was estimated, as stratified by periods dominated by the Delta variant (between September 1 and December 31, 2021) or Omicron variant (after January 1, 2022, to the end of follow-up on April 4, 2022). A Cox proportional hazard regression was used, adjusting for maternal age, parity, education, maternal country of birth, and county of residence.

RESULTS

Of 21 643 live-born infants, 9739 (45.0%) were born to women who received a second or third dose of a COVID-19 vaccine during pregnancy. The first 4 months of life incidence rate of a positive test for SARS-CoV-2 was 5.8 per 10 000 follow-up days. Infants of mothers vaccinated during pregnancy had a lower risk of a positive test compared with infants of unvaccinated mothers and lower risk during the Delta variant-dominated period (incidence rate, 1.2 vs 3.0 per 10 000 follow-up days; adjusted hazard ratio, 0.29; 95% CI, 0.19-0.46) compared with the Omicron period (incidence rate, 7.0 vs 10.9 per 10 000 follow-up days; adjusted hazard ratio, 0.67; 95% CI, 0.57-0.79).

CONCLUSIONS AND RELEVANCE

The results of this Norwegian population-based cohort study suggested a lower risk of a positive test for SARS-CoV-2 during the first 4 months of life among infants born to mothers who were vaccinated during pregnancy. Maternal COVID-19 vaccination may provide passive protection to young infants, for whom COVID-19 vaccines are currently not available.

The Impact of Timing of Pertussis Vaccination During Pregnancy on Infant Antibody Levels at Birth: A Multi-Country Analysis

Background

Pertussis vaccination during pregnancy is an effective strategy at reducing pertussis-related morbidity and mortality in infancy and is recommended across several countries. However, the optimal timepoint for vaccination in pregnancy to afford maximal protection to newborns is yet to be elucidated. This multi-country analysis aimed to model the impact of timing of vaccination during pregnancy on infant antibody titers at birth.

Methods

A multi-country analysis on a cohort of mother-infant pairs (n=698) vaccinated between 19.6-37.1 weeks gestation was conducted. Data taken from four parent studies on pertussis vaccination during pregnancy were modelled using natural cubic splines and linear mixed models to study the association of both gestational age at vaccination and the interval between vaccination and delivery with pertussis-specific cord blood antibody levels after pertussis vaccination during pregnancy.

Results

Term born infants on average achieve the highest antibody levels at birth if women are vaccinated before 31 weeks’ gestation. When considering both term and preterm deliveries, an interval of at least 7.5 weeks between vaccination and delivery is required to achieve the highest cord blood antibody levels. The models show that vaccinating earlier than these timeframes will also provide the infant with equally high antibody levels at birth.

Conclusions

Vaccinating in the second and early third trimester results in the highest antibody levels at birth. Vaccinating earlier within this window is needed to provide equal benefits to both term and preterm born infants.

Biological factors that may impair transplacental transfer of RSV antibodies: Implications for maternal immunization policy and research priorities for low- and middle-income countries

Respiratory syncytial virus (RSV) is the leading viral cause of acute lower respiratory tract infection (ALRI), including bronchiolitis and pneumonia, in infants and children worldwide. Protection against RSV is primarily antibody mediated and passively acquired RSV neutralizing antibody can protect infants from RSV ALRI. Maternal immunization is an attractive strategy for the prevention of RSV in early infancy when immune responses to active immunization may be suboptimal and most severe RSV disease and death occur. However, several biologic factors have been shown to potentially attenuate or interfere with the transfer of protective naturally acquired antibodies from mother to fetus and could therefore also reduce vaccine effectiveness through impairment of transfer of vaccine-induced antibodies. Many of these factors are prevalent in low- and middle-income countries (LMIC) which experience the greatest burden of RSV-associated mortality; more data are needed to understand these mechanisms in the context of RSV maternal immunization.

This review will focus on what is currently known about biologic conditions that may impair RSV antibody transfer, including preterm delivery, low birthweight, maternal HIV infection, placental malaria, and hypergammaglobulinemia (high levels of maternal total IgG). Key data gaps and priority areas for research are highlighted and include improved understanding of the epidemiology of hypergammaglobulinemia and the mechanisms by which it may impair antibody transfer. Key considerations for ensuring optimal vaccine effectiveness in LMICs are also discussed.

Regulatory considerations for study of infant protection through maternal immunization

Childhood Immunization is one of the critical strategies to decrease infant morbidity and mortality due to infectious diseases, but primary immunization schedules for infants in most countries start at 2 months of age. Childhood vaccines therefore begin providing adequate protection later in life, leaving infants vulnerable to infectious diseases and creating an immunity gap that results in higher morbidity and mortality among younger infants. Maternal immunization, the practice of vaccinating individuals during pregnancy, reduces the risk of infant infection primarily through the transfer of protective maternal antibodies to the fetus during late pregnancy. Although much progress has been made in public health policies to support maternal immunization research, inclusion of pregnant individuals and children in clinical trials remains challenging. This has resulted in paucity of evidence regarding safety and effectiveness of vaccines to support licensure of products intended for use during pregnancy and lactation to prevent disease in the infant. In addition, although safeguards for clinical research in pregnancy are supportive, experimental vaccines, e.g., Respiratory Syncytial Virus, are more complicated to study because data on safety, efficacy, and dosing are limited. This requires randomized controlled trials with safety monitoring for the mother, the fetus, and the infant with follow-up for at least 1 year or longer to assess long-term health outcomes that may be associated with peripartum vaccine exposure. The goal of this paper is to discuss the general regulatory considerations for clinical research to evaluate safety and effectiveness of vaccines administered during pregnancy to protect infants from disease. This could be useful to inform future vaccine trials. This discussion is not intended to provide agency guidance nor to articulate agency policy.

Intention to Receive COVID-19 Vaccine during Pregnancy: A Systematic Review and Meta-analysis

OBJECTIVE

This meta-analysis aimed to assess the level of intent to receive coronavirus disease 2019 (COVID-19) vaccination and demographical factors influencing vaccine uptake among pregnant individuals.

STUDY DESIGN

PubMed, Scopus, and archive/pre-print servers were searched up to May 22nd, 2021. Cross sectional surveys reporting the percentage of the pregnant individuals intending to get a COVID-19 vaccine were considered eligible for meta-analysis. This review was registered with PROSPERO (CRD42021254484). The primary outcome was to estimate the prevalence of COVID-19 vaccination intent among pregnant population. The secondary outcome was to evaluate the factors influencing the intention for vaccination.

RESULTS

Twelve studies sourcing data of 16,926 individuals who were identified as pregnant were eligible. The estimated intention for the receipt of COVID-19 vaccine among women who were pregnant was 47% (95% CI: 38-57%), with the lowest prevalence in Africa 19% (95% CI: 17-21%) and the highest in Oceania 48.0% (95% CI: 44.0-51.0%). Uptake of other vaccines (influenza and/or TdaP) during pregnancy was associated with higher rate of intent to receive the COVID-19 vaccine (OR = 3.03; 95% CI: 1.37-6.73; p = 0.006).

CONCLUSION

The intent to receive COVID-19 vaccine is relatively low among women who are pregnant and substantially varies based on the country of residence. In our meta-analysis, intent of women who were pregnant to receive the COVID-19 vaccine was significantly associated with the history of receiving influenza or TdaP vaccine during pregnancy. Given that in every country only a minority of gravidae have received the COVID-19 vaccine, despite known risks of maternal morbidity and mortality with no evidence of risks of vaccination, it highlights the importance of revised approaches at shared decision making and focused public health messaging by national and international advisories.

KEY POINTS

· The estimated global intention for COVID-19 vaccination among pregnant women was 47%.. · The lowest intention was in Africa and the highest in Oceania.. · These findings highlight the importance of public health messaging by by different agencies..

Epidemiology, prevention and control of pertussis in Spain: New vaccination strategies for lifelong protection

Pertussis is a highly contagious, vaccine-preventable respiratory tract infection, with high morbidity and mortality and a particularly severe effect on newborns and infants under 2 months. The first pertussis vaccines were introduced in the 1940s. Since 1980, however, the incidence of cases has risen despite the extensive vaccination programmes and antibiotic adjuvant treatments available. Transition from the use of whole-cell vaccines to acellular vaccines and the antigenic modifications of Bordetella pertussis have contributed, among other factors, to a reduction in vaccine-acquired immunity and reemergence of the disease. Today, there are still unmet needs not covered by conventional prevention measures and existing antibiotic treatments. This review aims to update the available data, and to discuss which vaccine strategies might contribute to better disease control and prevention.

Seroprevalence against Diphtheria in Pregnant Women and Newborns in Colombia: New Arguments to Promote Maternal Immunization

The tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine is recommended during pregnancy for neonatal protection against pertussis, although little is known of the protection it provides against diphtheria. The work used a cross-sectional design to estimate seroprevalence against diphtheria in 805 pregnant women with ≥37 gestation weeks and their newborns whose deliveries were attended in eight hospitals randomly chosen from a subregion of Antioquia, Colombia and to explore factors related with maternal protection. Levels of IgG antibodies were determined by using a commercial enzyme-linked immunosorbent assay test. Placental transfer of antibodies and crude and adjusted prevalence ratio (aPR) were analyzed to describe factors related with maternal protection against diphtheria. Protection against diphtheria was observed in 91.7% (95% CI 90.3–93.0) of the pregnant women and 93.1% (95% CI 91.7–94.4) of newborns, whose antibody levels were positively correlated (Spearman’s r = 0.769; p = 0.000). Maternal protection could be influenced by having been vaccinated during the current pregnancy (aPR 0.85, 95% CI: 0.82–0.93). The protective effect of vaccination during pregnancy and the efficiency of maternal antibody transfers were detected. Public health efforts should focus on increasing Tdap vaccination during each pregnancy to protect mothers and newborns against diphtheria.

Pertussis in Asia: Recent country-specific data and recommendations

The Global Pertussis Initiative (GPI) Roundtable Meeting held in 2019, which preceded the COVID-19 pandemic, focused on the incidence, surveillance, and immunization practices for pertussis in the Asian region. Participants from China, India, Indonesia, Malaysia, Pakistan, Philippines, South Korea, Taiwan, and Thailand presented country-specific information on pertussis prevalence, diagnosis, surveillance, vaccine administration and schedules, maternal and neonatal disease rates, and policies and practice of vaccination during pregnancy. In recent years, many Asian countries have seen an increase in pertussis cases, although underreporting of the disease is a concern. Currently, most Asian countries have only passive surveillance for pertussis in place. There is a need for improved surveillance to determine the disease burden and justify vaccination policies and recommendations, such as essential vaccination, boosters, and vaccination during pregnancy. Better awareness of the disease in adolescents and adults is necessary, and infant and childhood vaccination schedules need to be improved in many countries. Differences between private versus public sector vaccination schedules and between whole-cell and acellular pertussis vaccines should continue to be examined. It can be anticipated that unmet needs in the prevention and management of pertussis will continue as the COVID-19 pandemic evolves and that key recommendations highlighted in this meeting report will be of ongoing importance.

The optimal strategy for pertussis vaccination: a systematic review and meta-analysis of randomized control trials and real-world data

OBJECTIVE

Severe pertussis infection has been reported in infants before receiving routine immunization series. This problem could be solved by vaccinating mothers during pregnancy or children at birth. This study aimed to conduct a systematic review and meta-analysis of randomized controlled trials (RCTs) and real-world evidence to evaluate the optimal strategy for pertussis vaccination.

DATA SOURCES

PubMed, Embase, and the Cochrane Library databases were searched until December 2020.

STUDY ELIGIBILITY CRITERIA

RCTs, cohort studies, case-control studies, and case series were included if they investigated the efficacy, immunogenicity, and safety of acellular pertussis vaccine during pregnancy and at birth.

METHODS

Number of pertussis cases, severe adverse events (SAEs), and pertussis antibody concentration in infants before and after they receive routine vaccination series were extracted and random-effect model was used to pool the analyses.

RESULTS

Overall, 29 studies were included. Our meta-analysis revealed that pertussis immunization during pregnancy significantly increased the concentrations of 3 pertussis antibodies and reduced the incidence rates of infected infants below 3 months of age (odds ratio, 0.22; 95% confidence interval, 0.14-0.33). Similarly, infants vaccinated at birth had higher levels of pertussis antibody than those who were not. No significant difference in rates of severe adverse events was seen in all vaccination groups (during pregnancy [risk ratio, 1.18; 95% confidence interval, 0.76-1.82] and at birth [risk ratio, 0.72; 95% confidence interval, 0.34-1.54]).

CONCLUSION

Pertussis vaccination during pregnancy could protect infants against pertussis disease before the routine vaccination. Pertussis immunization at birth would be an alternative for infants whose mothers did not receive pertussis vaccines during pregnancy.

Improving vaccination rates in older adults and at-risk groups: focus on pertussis

Despite the implementation of effective paediatric vaccination programmes, pertussis remains a global health problem. Disease epidemiology has changed over time, shifting towards the adolescent and adult populations. In adults, the true burden of pertussis is greatly underestimated and pertussis vaccine coverage rates are suboptimal, including individuals with chronic conditions. Here, we report the outcomes of a virtual international scientific workshop to assess the evidence on the burden of pertussis in older adults and identify potential solutions to improve uptake of pertussis vaccines. In adults, pertussis is underdiagnosed in part due to atypical or milder clinical presentation and the lack of testing and case confirmation. However, contemporary epidemiological data denoted an increase in the burden of pertussis among adolescents and adults. This might be related to a variety of reasons including the waning of immunity over time, the lack of booster vaccination, and the improved diagnostic methods that led to increased recognition of the disease in adults. Pertussis sequelae can be severe in older adults, particularly those with existing chronic medical conditions, and the vulnerability of these groups is further enhanced by low pertussis vaccine coverage. Possible measures to increase vaccine uptake include strengthening and harmonisation of immunisation guidelines, healthcare professionals taking a more active role in recommending pertussis vaccination, involvement of vaccination centres and pharmacies in the vaccination process, and improving knowledge of pertussis burden and vaccine efficacy among the general population.

Global Perspectives on Immunization Against SARS-CoV-2 During Pregnancy and Priorities for Future Research: An International Consensus Paper From the World Association of Infectious Diseases and Immunological Disorders

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in pregnancy is associated with a higher risk for severe morbidity and mortality when compared with infection in non-pregnant women of childbearing age. An increasing number of countries recommend immunization against SARS-CoV-2 in pregnant women. Recent studies provide preliminary and supportive evidence on safety, immunogenicity and effectiveness of coronavirus disease 2019 (COVID-19) vaccines in pregnant women; however, important knowledge gaps remain which warrant further studies. This collaborative consensus paper provides a review of the current literature on COVID-19 vaccines in pregnant women, identifies knowledge gaps and outlines priorities for future research to optimize protection against SARS-CoV-2 in the pregnant women and their infants.

Improving uptake of vaccines in pregnancy: A service evaluation of an antenatal vaccination clinic at a tertiary hospital in the UK

Background

Vaccination against pertussis and seasonal influenza is recommended for all pregnant women in the UK. More recently COVID-19 vaccination has also been offered to women in pregnancy.

Objectives

To evaluate the uptake of vaccines in pregnant women within a midwife-led immunisation clinic and to assess factors influencing pregnant women's decisions about accepting vaccination.

Methods

Uptake of vaccines amongst pregnant women referred to a single UK centre for antenatal care between 01/01/19 and 02/10/19 was assessed. Interviews with 20 pregnant women explored views of antenatal vaccination and experiences of the vaccination service.

Findings

Amongst 4420 women, uptake was 90.6% for pertussis and 78.8% for influenza vaccines. Factors influencing vaccine-related decision-making amongst 20 interviewed women were: healthcare professional recommendation, perceived susceptibility and risk of infection, and previous experience of vaccination and vaccine-preventable disease.

Conclusions and Implications for Practice

Uptake of pertussis and influenza vaccines within a secondary care immunisation service was higher than the national or regional average. The model of vaccine delivery was associated with high levels of satisfaction. This model of vaccine delivery could be implemented elsewhere to increase vaccine uptake, and should be considered for delivery of COVID-19 vaccines in the future.

Vaccination in pregnancy against pertussis and seasonal influenza: key learnings and components from high-performing vaccine programmes in three countries: the United Kingdom, the United States and Spain

BACKGROUND

Pertussis and seasonal influenza are responsible for significant maternal, neonatal, and infant morbidity and mortality, but vaccine coverage rates (VCR) for both pertussis (administered as a tetanus, diphtheria, acellular pertussis [Tdap] vaccination) and seasonal influenza in pregnancy remain generally low. Only a small number of countries, including Spain, the United Kingdom (UK), and the United States (US), have high Tdap and seasonal influenza VCRs in pregnancy. The purpose of this study was to identify the key factors that contributed to the high VCRs observed in these countries.

METHODS

The experience from both Tdap and seasonal influenza vaccination programmes during pregnancy were documented in Spain, the UK, and the US using a three-step approach. A literature review yielded 157 publications, and a further 117 documents were selected through desk research. A published five-pillar VCR framework for influenza was amended to evaluate the specific contributing factors leading to high Tdap and seasonal influenza VCRs among pregnant women.

RESULTS

The analysis identified components that contributed to higher VCR in pregnant women across three different healthcare systems in Spain, UK, and US. The combination of several key interventions in each country led to a rapid increase in VCR that reached near-optimal levels (i.e. 75% for seasonal influenza) within a few years. As well as inclusion in national immunisation programme and vaccine reimbursement, key components that were identified included the mobilisation of health authorities, prenatal care Healthcare Professionals (HCP) and scientific societies, the inclusion of vaccination in antenatal medical guidance, the provision of educational material to HCPs, and a strong disease awareness driven by recent pertussis outbreaks in each country.

CONCLUSIONS

Although there is no simple, universal solution to improving sub-optimal VCRs, the list of components identified in this study from three countries with high-performing Tdap and seasonal influenza vaccination programmes provides a basis for public health and medical stakeholders in other countries to define strategies to successfully implement national vaccination programmes for pregnant women.

dTap vaccination uptake during pregnancy: Pregnant women-focused and health professionals-focused predictors in the Veneto Region (Italy)

BACKGROUND

Despite recommendations, the uptake of dTap maternal vaccination is still low in many countries. The reasons for this must be investigated both on the patient's and the healthcare professionals' sides.

METHODS

A record linkage study was performed linking Birth Assitance Certificates and dTap mothers' vaccination records (5183 deliveries) to describe the influence of socioeconomical and obstetrical-gynecological factors after the recommendations concerning dTap vaccination in pregnancy issued by the Italian Ministry of Health (August 2018). An interview was also administered to a subgroup of 656 new mothers on the occasion of the first vaccination of their newborns, in order to assess the dTap vaccination advice received from maternal care providers during pregnancy. A generalized linear model (binomial family, log link) was implemented to give a correct estimate of the mother's relative risk of being vaccinated.

RESULTS

Several pregnant women-focused factors are evident, but the most important ones are related to maternal care providers' practices: after mutual adjustment, the explicit advice towards dTap maternal vaccination given by the Obstetrician-Gynecologist or the Midwife is associated with a 12-fold increase in the dTap coverage.

CONCLUSIONS

Multiprofessional training is essential to make Obstetricians-Gynecologists and Midwives more confident in recommending dTaP maternal immunization.

Transplacental Antibody Transfer of Respiratory Syncytial Virus Specific IgG in Non-Human Primate Mother-Infant Pairs

One approach to protect new-borns against respiratory syncytial virus (RSV) is to vaccinate pregnant women in the last trimester of pregnancy. The boosting of circulating antibodies which can be transferred to the foetus would offer immune protection against the virus and ultimately the disease. Since non-human primates (NHPs) have similar reproductive anatomy, physiology, and antibody architecture and kinetics to humans, we utilized this preclinical species to evaluate maternal immunization (MI) using an RSV F subunit vaccine. Three species of NHPs known for their ability to be infected with human RSV in experimental challenge studies were tested for RSV-specific antibodies. African green monkeys had the highest overall antibody levels of the old-world monkeys evaluated and they gave birth to offspring with anti-RSV titers that were proportional to their mother. These higher overall antibody levels are associated with greater durability found in their offspring. Immunization of RSV seropositive AGMs during late pregnancy boosts RSV titers, which consequentially results in significantly higher titers in the vaccinated new-borns compared to the new-borns of unvaccinated mothers. These findings, accomplished in small treatment group sizes, demonstrate a model that provides an efficient, resource sparing and translatable preclinical in vivo system for evaluating vaccine candidates for maternal immunization.

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

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.

Epidemiology of Respiratory Pathogens Among Children Hospitalized for Pneumonia in Xiamen: A Retrospective Study

OBJECTIVES

To investigate the etiology of common respiratory pathogens in children < 2 years of age hospitalized with pneumonia in Xiamen from 2014 to 2017.

METHODS

The medical records of 5581 children with pneumonia were retrospectively reviewed. Direct immunofluorescent test was used for respiratory virus testing. Bacteria were detected by conventional culture method. The results of pathogen detection at admission were analyzed as well as the clinical outcomes of children.

RESULTS

The burden of hospitalized children with pneumonia was highest among infants < 6 months old (58.2%). Respiratory syncytial virus (RSV) was the most common respiratory virus (26.0%) followed by parainfluenza (4.8%) and adenovirus (3.2%). Haemophilus influenzae was the most common bacteria detected (16.6%) followed by Moraxella catarrhalis (13.4%), Staphylococcus aureus (13.0%), Streptococcus pneumoniae (12.3%), Escherichia coli (5.1%) and Klebsiella pneumoniae (4.8%). Notably, RSV and K. pneumoniae were detected more frequently in severe pneumonia (35.0% and 10.9%) versus mild pneumonia (25.6% and 4.6%), with higher rates of ICU admissions, longer hospital stays and higher hospital costs compared to those infected with other respiratory pathogens.

CONCLUSIONS

Among children < 2 years of age hospitalized with pneumonia in Xiamen, RSV was the most common respiratory virus, while H. influenzae and S. pneumoniae remained the predominant bacterial pathogens detected. Considering the low implementation rate of vaccines against pneumococcal and Hib pneumonia in China, there is an urgent need to increase both vaccination rates to reduce pneumococcal and Hib disease burden.

Is the Immunization of Pregnant Women against COVID-19 Justified?

Maternal immunization against some infectious diseases can offer significant advantages for women, preventing maternal morbidity and mortality, or for offspring, preventing fetal disease and conferring passive immunity to neonates. Recently, clinical trials specifically to evaluate the immunogenicity, safety, and tolerability of some of the available coronavirus disease 2019 (COVID-19) vaccines in pregnant and lactating women have been planned, initiated and, in some cases, completed. This paper discusses whether the immunization of pregnant women against COVID-19 is justified and presents knowledge about the immunogenicity and safety of mRNA COVID-19 vaccines for these subjects. The results of recent studies indicate that pregnant women are at increased risk of developing severe disease compared with nonpregnant women of the same age. Studies carried out with mRNA vaccines indicate that the immunogenicity, safety and tolerability of these preventive measures in pregnant women are not different from those in nonpregnant women of the same age. Moreover, antibodies are efficiently transferred through the placenta and can be detected in breastmilk, suggesting a potential prevention of infection in the child. All these findings authorize the use of mRNA vaccines in pregnant women to protect both the mother and the child. However, further studies with larger sample size and with follow-up of the pregnant women vaccinated during different periods of pregnancy and their children are needed to better characterize the immune response of pregnant women, to define when these vaccines should be administered to obtain the best protection, and to measure vaccine efficacy against virus variants in both mothers and infants. COVID-19 vaccines based on different technological platforms cannot presently be used, and their role in pregnant women should be clarified.

Coadministration of Anti-Viral Monoclonal Antibodies With Routine Pediatric Vaccines and Implications for Nirsevimab Use: A White Paper

Routine childhood vaccinations are key for the protection of children from a variety of serious and potentially fatal diseases. Current pediatric vaccine schedules mainly cover active vaccines. Active vaccination in infants is a highly effective approach against several infectious diseases; however, thus far, for some important viral pathogens, including respiratory syncytial virus (RSV), vaccine development and license by healthcare authorities have not been accomplished. Nirsevimab is a human-derived, highly potent monoclonal antibody (mAb) with an extended half-life for RSV prophylaxis in all infants. In this manuscript, we consider the potential implications for the introduction of an anti-viral mAb, such as nirsevimab, into the routine pediatric vaccine schedule, as well as considerations for coadministration. Specifically, we present evidence on the general mechanism of action of anti-viral mAbs and experience with palivizumab, the only approved mAb for the prevention of RSV infection in preterm infants, infants with chronic lung disease of prematurity and certain infants with hemodynamically significant heart disease. Palivizumab has been used for over two decades in infants who also receive routine vaccinations without any alerts concerning the safety and efficacy of coadministration. Immunization guidelines (Advisory Committee on Immunization Practices, Joint Committee on Vaccination and Immunization, National Advisory Committee on Immunization, Centers for Disease Control and Prevention, American Academy of Pediatrics, The Association of the Scientific Medical Societies in Germany) support coadministration of palivizumab with routine pediatric vaccines, noting that immunobiologics, such as palivizumab, do not interfere with the immune response to licensed live or inactivated active vaccines. Based on the mechanism of action of the new generation of anti-viral mAbs, such as nirsevimab, which is highly specific targeting viral antigenic sites, it is unlikely that it could interfere with the immune response to other vaccines. Taken together, we anticipate that nirsevimab could be concomitantly administered to infants with routine pediatric vaccines during the same clinic visit.

SARS-CoV-2 Vaccine Willingness among Pregnant and Breastfeeding Women during the First Pandemic Wave: A Cross-Sectional Study in Switzerland

As pregnant women are at high risk of severe SARS-CoV-2 infection and COVID-19 vaccines are available in Switzerland, this study aimed to assess the willingness of Swiss pregnant and breastfeeding women to become vaccinated. Through a cross-sectional online study conducted after the first pandemic wave, vaccination practices and willingness to become vaccinated against SARS-CoV-2 if a vaccine was available were evaluated through binary, multi-choice, and open-ended questions. Factors associated with vaccine willingness were evaluated through univariable and multivariable analysis. A total of 1551 women responded to questions related to the primary outcome. Only 29.7% (153/515) of pregnant and 38.6% (400/1036) of breastfeeding women were willing to get vaccinated against SARS-CoV-2 if a vaccine had been available during the first wave. Positive predictors associated with SARS-CoV-2 vaccine acceptance were an age older than 40 years, a higher educational level, history of influenza vaccination within the previous year, having an obstetrician as the primary healthcare practitioner, and being in their third trimester of pregnancy. After the first pandemic wave, Switzerland had a low SARS-CoV-2 vaccination acceptance rate, emphasizing the need to identify and reduce barriers for immunization in pregnant and breastfeeding women, particularly among the youngest and those with a lower educational level.

Epidemiology, prevention and control of pertussis in Spain: New vaccination strategies for lifelong protection

Pertussis is a highly contagious, vaccine-preventable respiratory tract infection, with high morbidity and mortality and a particularly severe effect on newborns and infants under 2 months. The first pertussis vaccines were introduced in the 1940s. Since 1980, however, the incidence of cases has risen despite the extensive vaccination programmes and antibiotic adjuvant treatments available. Transition from the use of whole-cell vaccines to acellular vaccines and the antigenic modifications of Bordetella pertussis have contributed, among other factors, to a reduction in vaccine-acquired immunity and reemergence of the disease. Today, there are still unmet needs not covered by conventional prevention measures and existing antibiotic treatments. This review aims to update the available data, and to discuss which vaccine strategies might contribute to better disease control and prevention.