Infants and the seasonal influenza vaccine. A global perspective on safety, effectiveness, and alternate forms of protection

A neonatal piglet model reveals interactions between nasal microbiota and influenza A virus pathogenesis

While vaccination and therapeutics for prevention/treatment of influenza are available, new strategies are needed to combat influenza disease in susceptible populations, particularly young children and newborns. Host associated microbiota play an important role in modulating the virulence of numerous pathogens, including the influenza A virus. In this study, we examined microbiome-influenza interactions in a neonatal piglet model system. The nasal microbiome of newborn piglets was longitudinally sampled before and after intranasal infection with recombinant viruses expressing hemagglutinins (HAs) derived from distinct zoonotic H1 subtypes. We found that viruses expressing different parental HAs manifested unique patterns of pathogenicity, and varied impacts on microbial community diversity. Despite these virus specific differences, a consistent microbial signature of viral infection was detected. Our results indicate that influenza A virus infection associates with the restructuring of nasal microbiome and such shifts in microbial diversity may contribute to outcomes of viral infection in neonatal piglets.

Influenza-associated respiratory illness among five cohorts of pregnant women and their young infants (0-6 months), Bangladesh, 2013-2017

Background

Pregnant women with their infants are considered at higher risk for influenza-associated complications, and the World Health Organization (WHO) recommends influenza vaccination during pregnancy to protect them, including their infants (0-6 months). There are limited data on the influenza burden among pregnant women and their infants (0-6 months), and there are no routine influenza vaccinations in Bangladesh.

Methods

Five annual cohorts (2013-2017) of pregnant women were enrolled from the eight sub-districts of Bangladesh before the influenza season (May-September); they were contacted weekly to identify new onset of influenza-like illness (ILI) (subjective or measured fever and cough) and acute respiratory illness (ARI) (at least two of these symptoms: cough, rhinorrhea, or difficulty in breathing) among their infants from birth to 6 months of age. We collected nasopharyngeal swabs from ILI and ARI cases, tested by real-time reverse transcription polymerase chain reaction (rRT-PCR) for influenza virus (including types and subtypes) and estimated influenza incidence (95% CI)/10000 pregnant women-months or infant-months, respectively.

Results

We enrolled 9020 pregnant women, followed for 26,709 pregnancy-months, and detected 1241 ILI episodes. We also followed 8963 infants for 51,518 infant-months and identified 5116 ARI episodes. Influenza positivity was 23% for ILI and 3% for ARI cases. The overall incidence (2013-2017) of influenza among pregnant women was 158.5/10000 pregnant women-months (95% CI: 141.4-177.6) and that among infants was 21.9/10000 infant-months (95% CI: 18.2-26.5).

Conclusions

Although the data was collected more than 5 years ago, as the only baseline data, our findings illustrate evidence of influenza burden among pregnant women and infants (0-6 months), which may support preventive policy decisions in Bangladesh.

External validation of the parental attitude about childhood vaccination scale

Introduction

Internal validation techniques alone do not guarantee the value of a model. This study aims to investigate the external validity of the Parental Attitude toward Childhood Vaccination (PACV) scale for assessing parents' attitude toward seasonal influenza vaccination.

Methods

Using a snowball sampling approach, an anonymous online questionnaire was distributed in two languages (English and Arabic) across seven countries. To assess the internal validity of the model, the machine learning technique of "resampling methods" was used to repeatedly select various samples collected from Egypt and refit the model for each sample. The binary logistic regression model was used to identify the main determinants of parental intention to vaccinate their children against seasonal influenza. We adopted the original model developed and used its predictors to determine parents' intention to vaccinate their children in Libya, Lebanon, Syria, Iraq, Palestine, and Sudan. The area under the curve (AUC) indicated the model's ability to distinguish events from non-events. We visually compared the observed and predicted probabilities of parents' intention to vaccinate their children using a calibration plot.

Results

A total of 430 parents were recruited from Egypt to internally validate the model, and responses from 2095 parents in the other six countries were used to externally validate the model. Multivariate regression analysis showed that the PACV score, child age (adolescence), and Coronavirus disease 2019 (COVID-19) vaccination in children were significantly associated with the intention to receive the vaccination. The AUC of the developed model was 0.845. Most of the predicted points were close to the diagonal line, demonstrating better calibration (the prediction error was 16.82%). The sensitivity and specificity of the externally validated model were 89.64 and 37.89%, respectively (AUC = 0.769).

Conclusion

The PACV showed similar calibration and discrimination across the six countries. It is transportable and can be used to assess attitudes towards influenza vaccination among parents in different countries using either the Arabic or English version of the scale.

The influence of air quality and meteorological variations on influenza A and B virus infections in a paediatric population in Singapore

INTRODUCTION

Influenza is an important cause of paediatric illness across the globe. However, information about the relationships between air pollution, meteorological variability and paediatric influenza A and B infections in tropical settings is limited.

METHODS

We analysed all daily reports of influenza A and B infections in children <5 years old obtained from the largest specialist women and children's hospital in Singapore. In separate negative binomial regression models, we assessed the dependence of paediatric influenza A and B infections on air quality and meteorological variability, using multivariable fractional polynomial modelling and adjusting for time-varying confounders.

RESULTS

Approximately 80% of 7329 laboratory-confirmed reports were caused by influenza A. We observed positive associations between sulphur dioxide (SO₂) exposure and the subsequent risk of infection with both influenza types. We observed evidence of a harvesting effect of SO₂ on Influenza A but not Influenza B. Ambient temperature was associated with a decline in influenza A reports (Relative Risk at lag 5 [RR_lag5]: 0.949, 95% CI: 0.916-0.983). Rainfall was positively associated with a subsequent increase in influenza A reports (RR_lag3: 1.044, 95% CI: 1.017-1.071). Nitrogen dioxide (NO₂) concentration was positively associated with influenza B reports (RR_lag5: 1.015, 95% CI: 1.005-1.025). There was a non-linear association between CO and influenza B reports. Absolute humidity increased the ensuing risk of influenza B (RR_lag5: 4.799, 95% CI: 2.277-10.118). Influenza A and B infections displayed dissimilar but predictable within-year seasonal patterns.

CONCLUSIONS

We observed different independent associations between air quality and meteorological variability with paediatric influenza A and B infections. Anticipated seasonal infection peaks and variations in air quality and meteorological parameters can inform the timing of community measures aimed at reducing influenza infection risk.

Influenza subtype-specific maternal antibodies protect offspring against infection but inhibit vaccine-induced immunity and protection in mice

Following influenza A virus (IAV) infection or vaccination during pregnancy, maternal antibodies are transferred to offspring in utero and during lactation. The age and sex of offspring may differentially impact the transfer and effects of maternal immunity on offspring. To evaluate the effects of maternal IAV infection on immunity in offspring, we intranasally inoculated pregnant mice with sublethal doses of mouse-adapted (ma) H1N1, maH3N2, or media (mock) at embryonic day 10. In offspring of IAV-infected dams, maternal subtype-specific antibodies peaked at postnatal day (PND) 23, remained detectable through PND 50, and were undetectable by PND 105 in both sexes. When offspring were challenged with homologous IAV at PND 23, both male and female offspring had greater clearance of pulmonary virus and less morbidity and mortality than offspring from mock-inoculated dams. Inactivated influenza vaccination (IIV) against homologous IAV at PND 23 caused lower vaccine-induced antibody responses and protection following live virus challenge in offspring from IAV than mock-infected dams, with this effect being more pronounced among female than male offspring. At PND 105, there was no impact of maternal infection status, but vaccination induced greater antibody responses and protection against challenge in female than male offspring of both IAV-infected and mock-inoculated dams. To determine if maternal antibody or infection interfered with vaccine-induced immunity and protection in early life, offspring were vaccinated and challenged against a heterosubtypic IAV (i.e., different IAV group than dam) at PND 23 or 105. Heterosubtypic IAV maternal immunity did not affect antibody responses after IIV or protection after live IAV challenge of vaccinated offspring at either age. Subtype-specific maternal IAV antibodies, therefore, provide protection independent of offspring sex but interfere with vaccine-induced immunity and protection in offspring with more pronounced effects among females than males.

Immunization of preterm infants: current evidence and future strategies to individualized approaches

Preterm infants are at particularly high risk for infectious diseases. As this vulnerability extends beyond the neonatal period into childhood and adolescence, preterm infants benefit greatly from infection-preventive measures such as immunizations. However, there is an ongoing discussion about vaccine safety and efficacy due to preterm infants' distinct immunological features. A significant proportion of infants remains un- or under-immunized when discharged from primary hospital stay. Educating health care professionals and parents, promoting maternal immunization and evaluating the potential of new vaccination tools are important means to reduce the overall burden from infectious diseases in preterm infants. In this narrative review, we summarize the current knowledge about vaccinations in premature infants. We discuss the specificities of early life immunity and memory function, including the role of polyreactive B cells, restricted B cell receptor diversity and heterologous immunity mediated by a cross-reactive T cell repertoire. Recently, mechanistic studies indicated that tissue-resident memory (Trm) cell populations including T cells, B cells and macrophages are already established in the fetus. Their role in human early life immunity, however, is not yet understood. Tissue-resident memory T cells, for example, are diminished in airway tissues in neonates as compared to older children or adults. Hence, the ability to make specific recall responses after secondary infectious stimulus is hampered, a phenomenon that is transcriptionally regulated by enhanced expression of T-bet. Furthermore, the microbiome establishment is a dominant factor to shape resident immunity at mucosal surfaces, but it is often disturbed in the context of preterm birth. The proposed function of Trm T cells to remember benign interactions with the microbiome might therefore be reduced which would contribute to an increased risk for sustained inflammation. An improved understanding of Trm interactions may determine novel targets of vaccination, e.g., modulation of T-bet responses and facilitate more individualized approaches to protect preterm babies in the future.

Influenza hospitalizations in Australian children 2010-2019: The impact of medical comorbidities on outcomes, vaccine coverage, and effectiveness

BACKGROUND

Children with comorbidities are at greater risk of severe influenza outcomes compared with healthy children. In Australia, influenza vaccination was funded for those with comorbidities from 2010 and all children aged <5 years from 2018. Influenza vaccine coverage remains inadequate in children with and without comorbidities.

METHODS

Children ≤16 years admitted with acute respiratory illness and tested for influenza at sentinel hospitals were evaluated (2010-2019). Multivariable regression was used to identify predictors of severe outcomes. Vaccine effectiveness was estimated using the modified incidence density test-negative design.

RESULTS

Overall, 6057 influenza-confirmed hospitalized cases and 3974 test-negative controls were included. Influenza A was the predominant type (68.7%). Comorbidities were present in 40.8% of cases. Children with comorbidities were at increased odds of ICU admission, respiratory support, longer hospitalizations, and mortality. Specific comorbidities including neurological and cardiac conditions increasingly predisposed children to severe outcomes. Influenza vaccine coverage in influenza negative children with and without comorbidities was low (33.5% and 17.9%, respectively). Coverage improved following introduction of universal influenza vaccine programs for children <5 years. Similar vaccine effectiveness was demonstrated in children with (55% [95% confidence interval (CI): 45; 63%]) and without comorbidities (57% [(95%CI: 44; 67%]).

CONCLUSIONS

Comorbidities were present in 40.8% of influenza-confirmed admissions and were associated with more severe outcomes. Children with comorbidities were more likely experience severe influenza with ICU admission, mechanical ventilation, and in-hospital morality. Despite demonstrated vaccine effectiveness in those with and without comorbidities, vaccine coverage was suboptimal. Interventions to increase vaccination are expected to reduce severe influenza outcomes.

Methodologic approaches in studies using real-world data (RWD) to measure pediatric safety and effectiveness of vaccines administered to pregnant women: A scoping review

OBJECTIVE

This scoping review mapped studies using real-world data (RWD) to measure pediatric safety and effectiveness of vaccines administered to pregnant women.

INTRODUCTION

In the US, two vaccines are recommended for all pregnant women to prevent illness in the infant: inactivated influenza vaccine (recommended since 2004), and the combined tetanus-diphtheria-acellular pertussis (Tdap) vaccine (recommended since 2013). This scoping review maps the studies conducted to date that address questions about pediatric safety and effectiveness of vaccines administered during pregnancy and provides a knowledge base for evaluating the use of RWD to study this issue.

METHODS

The scoping review was conducted following a published protocol. Methods included an electronic search of PubMed and Embase, screening of titles and abstracts by two reviewers, and double extraction of data for summary and synthesis. Studies that reported on pregnant women and the effectiveness or safety outcomes in their infants were included.

RESULTS

Forty-eight studies met the inclusion criteria of the scoping review protocol using RWD to assess safety or effectiveness of influenza or pertussis vaccinations administered to pregnant women with respect to pregnancy, infant or child outcomes. Detailed information about data sources, linkage of maternal and infant data, and operational definitions for gestational age were largely absent from the majority of studies raising concerns about reproducibility and validity of study findings.

CONCLUSIONS

A body of literature is available from which to plan and design future studies of vaccination in pregnant women using RWD. This is of intense importance as new vaccines, such as those for COVID-19, become available to the general population via approval or authorization without inclusion of pregnant women in the clinical trials.

Methodologic approaches in studies using real-world data to measure pediatric safety and effectiveness of vaccines administered to pregnant women: a scoping review protocol

OBJECTIVE

This scoping review aims to map studies using real-world data (RWD) to measure pediatric safety and effectiveness of vaccines administered to pregnant women.

INTRODUCTION

In the United States, two vaccines are recommended for all pregnant women to prevent illness in the infant: inactivated influenza vaccine (recommended since 2004) and the combined tetanus-diphtheria-acellular pertussis (Tdap) vaccine (recommended since 2013). Because of the ethical constraints in conducting randomized clinical trials to measure the effects on the infant, there is great interest in using electronic health care data or administrative claims data to study the effects of maternal immunization on the infant's health, and it is anticipated that such studies may be submitted to support regulatory decision-making. This scoping review will map the studies conducted to date that address these questions and provide a context for considering the regulatory issues that may arise in the future.

INCLUSION CRITERIA

Studies that report on pregnant women receiving immunization and the effectiveness or safety outcomes in their infants will be included. Study participants may be from any population or country, of any reproductive age, and with any health status. Studies will be included if they use real-world data (from electronic health records, administrative claims, pharmacy benefit records, or registries).

METHODS

An electronic search of PubMed and Embase will identify citations for screening. The search will be limited to studies published in English during the preceding 10 years. Two reviewers will screen citations in a two-step process (titles and abstracts, then full-text articles), and two reviewers will extract data for summary and synthesis.

Simultaneous Influenza Vaccination and Hymenoptera Venom Immunotherapy Is Safe

Allergen immunotherapy (AIT) is a standard treatment for venom allergy. Our purpose was to determine if the administration of both allergen and protective vaccines during one visit is safe and if such a procedure does not deteriorate the tolerance of both vaccines. As current guidelines are based on theoretical assumptions, our aim was to establish the safety and tolerance of shortening the recommended interval between vaccinations. During two influenza seasons, 44 adult patients, with a history of systemic allergic reactions after a Hymenoptera sting, underwent 58 simultaneous allergen and seasonal influenza vaccinations (study group) while in the maintenance phase of venom immunotherapy (VIT). The control group consisted of 57 healthy adults who were vaccinated against influenza only. The conditions of the patients were monitored during hospital visits, and via telecommunication methods to evaluate the safety and tolerance of the procedure. Within the study group, there were no immediate or delayed allergic reactions after vaccinations. The presence of common, adverse influenza vaccine reactions among study group patients (29%) and control group patients (32%) did not differ significantly (p = 0.841). We did not observe a difference in the frequency of various adverse reactions in either group or a dependence of previous vaccinations against influenza on the occurrence of adverse reactions. The most frequent occurrences were local adverse reactions. All adverse reactions were resolved without treatment. These findings demonstrate the safety and tolerance of an influenza vaccination and Hymenoptera venom immunotherapy administration during one visit.

Safety and immunogenicity of high doses of quadrivalent influenza vaccine in children 6 months through <18 years of age: A randomized controlled phase II dose-finding trial

Quadrivalent high-dose inactivated influenza vaccine (Fluzone® High-Dose Quadrivalent, IIV4-HD) was licensed in the USA in 2019 for adults ≥ 65 years of age. This Phase II study examined safety and immunogenicity of 3 dose formulations of IIV4-HD in healthy children. In a randomized, modified double-blind, active-controlled trial in the USA and Canada, 661 children aged 6 months through < 18 years received 1 or 2 doses intramuscularly of standard-dose quadrivalent influenza vaccine (IIV4-SD; 15 µg HA/strain), IIV4-HD at 3 dose levels (30, 45, and 60 µg HA/strain), or adjuvanted trivalent influenza vaccine (aIIV3, 7.5 µg HA/strain). Rates of unsolicited AEs were similar irrespective of dose. No treatment-related serious adverse events or deaths were reported. Reactogenicity was slightly higher for IIV4-HD than IIV4-SD, although most solicited reactions were grade 1 or 2. Hemagglutination inhibition (HAI) and seroneutralization antibody titers were measured 28-35 days after each dose. Geometric mean HAI titers increased with increasing hemagglutinin dose, especially in children 6 months through < 3 years. For IIV4-HD 60 µg, in participants 6 months through < 18 years of age, the geometric mean titer ratio (95% confidence interval) versus IIV4-SD was 1.35 (0.94, 1.94) for A/H1N1, 2.51 (1.77, 3.55) for A/H3N2, 1.60 (1.17, 2.18) for B/Victoria, and 1.51 (1.13, 2.03) for B/Yamagata. The GMT ratio (95% confidence interval) for IIV4-HD 60 µg versus IIV4-SD was highest for participants 6 months through < 3 years of age: 4.24 (2.05, 8.76) for A/H1N1, 3.14 (1.53, 6.44) for A/H3N2, 2.04 (1.10, 3.77) for B/Victoria, and 1.92 (1.08, 3.41) for B/Yamagata; similarly, seroneutralization antibody GMT ratio was highest in these participants: 170 (84.6, 340) for A/H1N1, 7.13 (4.90, 10.4) for A/H3N2, 35.8 (22.1, 58.1) for B/Victoria, and 22.7 (14.7, 35.0) for B/Yamagata. This study showed that IIV4-HD (60 µg HA/strain) provides improved immunogenicity without affecting vaccine safety in children.

Effect of educational and financial incentive-based interventions on immunization attitudes, beliefs, intentions and receipt among close contacts of pregnant women

INTRODUCTION

Cocooning, the vaccination of close contacts of a newborn, is a strategy to limit the risk of pertussis and influenza infection among vulnerable infants.

METHODS

Pregnant women in Colorado and Georgia referred close contacts to an app that provided tailored educational videos about vaccines along with a small pharmacy-based financial incentive for vaccine receipt. The primary objective of this study was to determine the feasibility of implementing this app-based cocooning intervention.

RESULTS

Two hundred seventy seven contacts were enrolled in this study. Of those who received the educational videos, 96% found them interesting, 100% found them clear to understand, 97% found them helpful, and 99% trusted them. Completion of the videos led to significant increases in influenza vaccine knowledge (p = 0.025), Tdap vaccine knowledge (p < 0.001), and intention to receive these vaccines (p = 0.046). Of the 136 participants who reported receiving influenza vaccine, 41 (30%) reported receiving it at a pharmacy, and of the 66 who reported receiving Tdap vaccine, 15 (23%) reported receiving it at a pharmacy. Of all participants, 80% reported being comfortable receiving vaccines at a pharmacy instead of a doctor's office. The provision of small pharmacy-based financial incentives combined with individually-tailored educational videos about vaccines led to 6.97 (95%CI: 2.25-21.64) times higher odds of self-reported receipt of influenza vaccine than providing small pharmacy-based financial incentives without these videos. No significant difference was found for Tdap vaccine.

CONCLUSIONS

Tailored vaccine education can positively impact vaccine knowledge and intentions among adults. An app-based referral program providing education and financial incentives for cocooning vaccination at pharmacies is feasible.

Vaccination of Term and Preterm Infants

Newborns, especially those born preterm, are at high risk for infection. Preterm birth rates appear to be increasing in most countries, with ∼15 million infants born preterm globally each year, corresponding to ∼11% of all deliveries. Importantly, the vulnerability of preterm infants to infection continues beyond the perinatal period, following them throughout childhood and adolescence, highlighting the long-lasting effects of infection on overall health and well-being. Other than access to clean drinking water and proper sewage systems, immunization is the most effective biomedical intervention to reduce early life infection. Nevertheless, a significant proportion of infants discharged on or after 2 months of age from the NICU remains unimmunized or underimmunized at that time. Despite being safe and effective, protective responses to immunization in early life are different from those in older individuals, in part because of the distinct immune system of newborns and young infants. The paradigms of the Bacille Calmette-Guérin, hepatitis B, and polio vaccines, the only immunizations currently routinely administered in the neonatal period, provide evidence that it is feasible to successfully administer vaccines via different routes of delivery; thus, production of sufficient vaccine-induced immunity leads to disease prevention in the newborn. Strategies such as maternal immunization, adjuvantation systems, leveraging trained immunity, and counseling caregivers can be used to enhance vaccine-induced specific and heterologous protection from infection and boost adherence to the recommended immunization schedule.

Feasibility and acceptability of the multi-component P3-MumBubVax antenatal intervention to promote maternal and childhood vaccination: A pilot study

BACKGROUND

Pregnancy is a critical time for vaccine decision-making, but coverage remains suboptimal for maternal influenza (45-60%) and pertussis vaccination (65-80%) in Australia. The multi-component P3-MumBubVax intervention has been designed for Australian midwives to optimise antenatal vaccine discussions and improve maternal and childhood vaccine uptake. A pilot study was conducted to assess intervention feasibility and acceptability.

METHODS

P3-MumBubVax includes components at three levels: 1. Practice ('vaccine champions'; stickers to prompt and record vaccine discussions/delivery); 2. Provider (website with vaccine communication training; learning exercise; fact sheets; links to child vaccination resources); 3. Parent (SMS reminders; website; fact sheets). Midwives and pregnant women 18-22 weeks gestation were recruited at the Royal Women's Hospital, Melbourne. Post-intervention online surveys assessed intervention feasibility, implementation, acceptability and impact on vaccine uptake.

RESULTS

Twenty-five midwives and 62 pregnant women were recruited and 19/25 midwives completed training. Surveys were returned by 18/25 midwives and 56/62 women. 14/18 midwives reported using the sticker prompts, 10/18 reported using or referring to the website, and 11/18 reported using the fact sheets. 48/56 pregnant women (86%) reported discussing influenza and 46/56 (82%) discussed pertussis vaccines with their midwives. These conversations were reported to be short (1-3 min) for 48/56 women (87%). All midwives were satisfied with the intervention and 17/18 reported feeling more confident discussing vaccines following the intervention. Women were very satisfied with SMS content (50/56; 94%) and timing (49/55; 89%), and with their vaccine discussions in general (34/56; 63%). However, 16/54 (30%) wanted more discussion about childhood vaccines. Self-reported maternal vaccine uptake was 82% (45/55) and 93% (51/55) for influenza and pertussis (baseline 2017-2018: 43% influenza, 60% pertussis) and 96% (50/52) of infants were fully vaccinated at 12 weeks.

DISCUSSION

The P3-MumBubVax intervention is feasible and acceptable in the Australian public antenatal setting. Further evaluation is required to determine effectiveness.

Age inappropriate influenza vaccination in infants less than 6 months old, 2010-2018

BACKGROUND

Annual influenza vaccination is recommended for persons 6 months or older and vaccination in infants less than 6 months old is a vaccine administration error. There are limited safety studies in this population, particularly among infants less than 6 weeks old.

METHODS

We searched the U.S. Vaccine Adverse Event Reporting System (VAERS) database for reports of adverse events (AEs) following influenza vaccination in infants less than 6 months old for the 2010-2018 influenza seasons. We conducted a descriptive and qualitative analysis of reports to describe AEs and identify possible risk factors.

RESULTS

In total, 114 reports were identified; only 21 reported a specific AE. Pyrexia, irritability, crying and diarrhea were the most common symptoms. There were 12 reports involving newborns; the most common circumstance cited was confusion with the birth dose of hepatitis B vaccine. The following risk factors were identified: (1) individuals getting vaccinated together resulting in patient mix-ups; (2) healthcare provider not verifying the patient's information; (3) individual provider confusion due to similarities in vaccines' packaging and names of vaccines that sound alike.

CONCLUSIONS

Reports identified of influenza vaccination in infants less than 6 months old indicate that vaccination errors in this age group are occurring and healthcare providers who vaccinate infants should be aware of how to prevent such events. Our study adds to the existing literature by providing valuable information regarding the general absence of serious adverse events in the case of vaccination errors associated with inadvertent influenza vaccine within this population.

Factors associated with referring close contacts to an app with individually-tailored vaccine information

BACKGROUND

Infants too young to be fully vaccinated are vulnerable to potentially deadly influenza and pertussis infections. The cocooning strategy limits this risk by vaccinating those likely to interact with the infant and mother during this vulnerable time, such as close friends and family members. Distribution of accurate and accessible vaccine information through existing social networks could be an important tool in increasing vaccine confidence and coverage.

METHODS

We surveyed 1095 pregnant women from diverse prenatal care practices in Georgia and Colorado. These women were surveyed through a mobile app to assess vaccine intentions, attitudes, beliefs, norms, and levels of trust, and then presented brief individually-tailored educational videos about maternal and infant vaccines and the cocooning strategy. They were then given the opportunity to refer up to six contacts to enroll in the app and receive similar vaccine education.

RESULTS

Twenty-eight percent of these women referred at least one contact, with an average of 2.67 contacts per referring woman. Most referrals (93%) were partners, parents, siblings, relatives, or close friends. Attitudinal constructs significantly associated with increased likelihood of referring contacts included: intention to receive maternal influenza vaccine, perceived safety of maternal Tdap vaccine, perceived efficacy of maternal influenza vaccine, perceived susceptibility to and severity of influenza during pregnancy, and trust in vaccine information from the Centers for Disease Control and Prevention (CDC) and academic institutions. Uncertainty about infant vaccine intentions was associated with decreased likelihood of referring contacts.

CONCLUSIONS

Pregnant women who valued vaccination and trusted vaccine information from academic institutions were more likely to refer an educational app about vaccines than those who did not. Further research is needed to determine the potential impact of this strategy on vaccine coverage when implemented on a large scale.

TRIAL REGISTRATION

The survey informing this article was part of a randomized controlled trial funded by the National Institutes of Health [clinicaltrials.gov registration number NCT02898688].

Routine Childhood Vaccines Given in the First 11 Months of Life

The US Advisory Committee on Immunization Practices recommends that infants beginning at birth receive several vaccines directed against a variety of infectious diseases that currently pose threats of morbidity and mortality to infants and those around them, including the 3-dose hepatitis B (HepB) series. The first dose is due at birth. This series protects against maternal-infant transmission of the HepB virus and against exposure the rest of the infant's life. At age 2 months infants are to receive not only their second dose of HepB vaccine but also a series of vaccines directed against diphtheria, tetanus, pertussis, pneumococcus, rotavirus, poliovirus, and Haemophilus influenzae type b. At 4 months, infants are to repeat those vaccines except for the HepB vaccine. At age 6 months infants are to finish the HepB series and receive the third doses of the other vaccines received at 2 and 4 months except for the rotavirus vaccine, depending on the brand used. Also, starting at 6 months, depending on the time of year, infants are to begin a 2-dose series against influenza separated by 28 days. Each of these vaccines is due at a time when the vaccine works to protect against an immediate risk and to provide long-term protection. These vaccine-preventable diseases vary in terms of the nature of exposure, the form of the morbidity, the risk of mortality, and the ability of routine vaccination to prevent or ameliorate harm.

Seasonal influenza vaccination policies in the Eastern Mediterranean Region: Current status and the way forward

BACKGROUND

The World Health Organization recommends annual influenza vaccination, especially in high-risk groups. Little is known about the adoption and implementation of influenza vaccination policies in the Eastern Mediterranean Region.

METHODS

A survey was distributed to country representatives at the ministries of health of the 22 countries of the Region between December 2016 and February 2017 to capture data on influenza immunization policies, recommendations, and practices in place.

RESULTS

Of the 20 countries that responded to the survey, 14 reported having influenza immunization policies during the 2015/2016 influenza season. All countries with an influenza immunization policy recommended vaccination for people with chronic medical conditions, healthcare workers and pilgrims. Two of the 20 countries did not target pregnant women. Eight countries used the northern hemisphere formulation, one used the southern hemisphere formulation and nine used both. Vaccination coverage was not monitored by all countries and for all target groups. Where reported, coverage of a number of target groups (healthcare workers, children) was generally low. Data on the burden of influenza and vaccine protection are scarce in the Region.

CONCLUSIONS

Despite widespread policy recommendations on influenza vaccination, attaining high coverage rates remains a challenge in the Eastern Mediterranean Region. Tackling disparities in influenza vaccine accessibility and strengthening surveillance systems may increase influenza vaccine introduction and use.

Does Choice of Influenza Vaccine Type Change Disease Burden and Cost-Effectiveness in the United States? An Agent-Based Modeling Study

Offering a choice of influenza vaccine type may increase vaccine coverage and reduce disease burden, but it is more costly. This study calculated the public health impact and cost-effectiveness of 4 strategies: no choice, pediatric choice, adult choice, or choice for both age groups. Using agent-based modeling, individuals were simulated as they interacted with others, and influenza was tracked as it spread through a population in Washington, DC. Influenza vaccination coverage derived from data from the Centers for Disease Control and Prevention was increased by 6.5% (range, 3.25%-11.25%), reflecting changes due to vaccine choice. With moderate influenza infectivity, the number of cases averaged 1,117,285 for no choice, 1,083,126 for pediatric choice, 1,009,026 for adult choice, and 975,818 for choice for both age groups. Averted cases increased with increased coverage and were highest for the choice-for-both-age-groups strategy; adult choice also reduced cases in children. In cost-effectiveness analysis, choice for both age groups was dominant when choice increased vaccine coverage by ≥3.25%. Offering a choice of influenza vaccines, with reasonable resultant increases in coverage, decreased influenza cases by >100,000 with a favorable cost-effectiveness profile. Clinical trials testing the predictions made based on these simulation results and deliberation of policies and procedures to facilitate choice should be considered.