Prevention of influenza in healthy children

Mapping trends and hotspots in research on global influenza vaccine hesitancy: A bibliometric analysis

Background and Aims

Influenza is one of the most widespread respiratory infections and poses a huge burden on health care worldwide. Vaccination is key to preventing and controlling influenza. Influenza vaccine hesitancy is an important reason for the low vaccination rate. In 2019, Vaccine hesitancy was identified as one of the top 10 threats to global health by the World Health Organization. However, there remains a glaring scarcity of bibliometric research in that regard. This study sought to identify research hotspots and future development trends on influenza vaccine hesitation and provide a new perspective and reference for future research.

Methods

We retrieved publications on global influenza vaccine hesitancy from the Web of Science Core Collection database, Scopus, and PubMed databases from inception to 2022. This study used VOSviewer and CiteSpace for visualization analysis.

Results

Influenza vaccine hesitancy-related publications increased rapidly from 2012 and peaked in 2022. One hundred and nine countries contributed to influenza vaccine hesitation research, and the United States ranked first with 541 articles and 7161 citations. Vaccines-Basel was the journal with the largest number of published studies on influenza vaccine hesitations. MacDonald was the most frequently cited author. The most popular research topics on influenza vaccine hesitancy were (1) determinants of influenza vaccination in specific populations, such as healthcare workers, children, pregnant women, and so on; (2) influenza and COVID-19 vaccine hesitancy during the COVID-19 pandemic.

Conclusions

The trend in the number of annual publications related to influenza vaccine hesitancy indicating the COVID-19 pandemic will prompt researchers to increase their attention to influenza vaccine hesitancy. With healthcare workers as the key, reducing vaccine hesitancy and improving vaccine acceptance in high-risk groups will be the research direction in the next few years.

Association between handwashing and gargling education for children and prevention of respiratory tract infections: a longitudinal Japanese children population-based study

PURPOSE

A longitudinal study was conducted to examine the effects of handwashing and gargling education for children on the prevention of respiratory tract infections (RTIs) in children in Japan.

METHODS

The study included 38,554 children born in 2010 who were enrolled in a longitudinal study. Information on children's hygiene education regarding handwashing and gargling was collected in a survey at the age of 3.5 years. Based on parents' reports of doctors' diagnoses, airway infections and influenza events in the 12-month duration before the survey were evaluated for RTIs at the ages of 4.5 and 9 years. Poisson regression with robust variance was performed to examine the effects of hygiene education on RTIs prevention. The supplementary analysis was stratified by household income.

RESULTS

Children were categorized into different groups: 38% in the handwashing and gargling group, 29% in the handwashing group, 0.1% in the gargling group, and 9.7% in the no-education group. Exclusions were made for non-respondent children (23%) and those in the gargling group. Hygiene education was associated with decreased influenza at the age of 4.5 years in the handwashing (adjusted RR [aRR] = 0.8; 95% CI, 0.8-0.9) and handwashing and gargling groups (aRR = 0.8; 95% CI, 0.8-0.9) compared with no education. However, no preventive effects on airway infections at the age of 4.5 and 9, influenza at the age of 9, or hospitalization between the ages of 3.5 and 9 years were detected. Handwashing and gargling could significantly prevent influenza in low-income households (aRR = 0.7; 95% CI, 0.6-0.8).     Conclusions: Gargling education was widespread and mostly combined with handwashing education in Japan. Hygiene education significantly affected prevention of influenza infections at the age of 4.5 years, especially in low-income households.

WHAT IS KNOWN

• Previous intervention studies showed handwashing and gargling are effective in preventing respiratory tract infections.

WHAT IS NEW

• We conducted a longitudinal study on handwashing and gargling education in Japanese children and found that handwashing and gargling were widely practiced together. • Handwashing and gargling education were related to a reduction in influenza, particularly in low-income households.

The Value(s) of Vaccination: Building the Scientific Evidence According to a Value-Based Healthcare Approach

Objectives

To provide a new value-based immunization approach collating the available scientific evidence on the topic.

Methods

Four value pillars (personal, allocative, technical, and societal) applied to vaccination field were investigated. A systematic literature review was performed querying three database from December 24th, 2010 to May 27th, 2020. It included studies on vaccine-preventable diseases (VPDs) that mentioned the term value in any part and which were conducted in advanced economies. An in-depth analysis was performed on studies addressing value as key element.

Results

Overall, 107 studies were considered. Approximately half of the studies addressed value as a key element but in most of cases (83.3%) only a single pillar was assessed. Furthermore, the majority of papers addressed the technical value by looking only at classical methods for economic assessment of vaccinations whereas very few dealt with societal and allocative pillars.

Conclusions

Estimating the vaccinations value is very complex, even though their usefulness is certain. The assessment of the whole value of vaccines and vaccinations is still limited to some domains and should encompass the wider impact on economic growth and societies.

Nutraceuticals in the Prevention of Viral Infections, including COVID-19, among the Pediatric Population: A Review of the Literature

In recent years, there has been a growth in scientific interest in nutraceuticals, which are those nutrients in foods that have beneficial effects on health. Nutraceuticals can be extracted, used for food supplements, or added to foods. There has long been interest in the antiviral properties of nutraceuticals, which are especially topical in the context of the ongoing COVID-19 pandemic. Therefore, the purpose of this review is to evaluate the main nutraceuticals to which antiviral roles have been attributed (either by direct action on viruses or by modulating the immune system), with a focus on the pediatric population. Furthermore, the possible applications of these substances against SARS-CoV-2 will be considered.

Evolution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as coronavirus disease 2019 (COVID-19) pandemic: A global health emergency

According to data compiled by researchers at Johns Hopkins University in Baltimore, Maryland, more than two and half million cases of coronavirus disease 2019 (COVID-19), caused by a newly discovered virus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), have been confirmed on April 20, 2020 (Nature, 2020b). Since the emergence of this infectious disease in Asia (Wuhan, China) late last year, it has been subsequently span to every continent of the world except Antarctica (Rodríguez-Morales et al., 2020). Along with a foothold in every country, the current disease pandemic is disrupting practically every aspect of life all over the world. As the outbreak are continuing to evolve, several research activities have been conducted for better understanding the origin, functions, treatments, and preventions of this novel coronavirus. This review will be a summa of the key features of novel coronavirus (nCoV), the virus causing disease 2019 and the present epidemic situation worldwide up to April 20, 2020. It is expected that this record will play an important role to take more preventive measures for overcoming the challenges faced during this current pandemic.

The Potential Health Care Costs And Resource Use Associated With COVID-19 In The United States

With the coronavirus disease 2019 (COVID-19) pandemic, one of the major concerns is the direct medical cost and resource use burden imposed on the US health care system. We developed a Monte Carlo simulation model that represented the US population and what could happen to each person who got infected. We estimated resource use and direct medical costs per symptomatic infection and at the national level, with various "attack rates" (infection rates), to understand the potential economic benefits of reducing the burden of the disease. A single symptomatic COVID-19 case could incur a median direct medical cost of $3,045 during the course of the infection alone. If 80 percent of the US population were to get infected, the result could be a median of 44.6 million hospitalizations, 10.7 million intensive care unit (ICU) admissions, 6.5 million patients requiring a ventilator, 249.5 million hospital bed days, and $654.0 billion in direct medical costs over the course of the pandemic. If 20 percent of the US population were to get infected, there could be a median of 11.2 million hospitalizations, 2.7 million ICU admissions, 1.6 million patients requiring a ventilator, 62.3 million hospital bed days, and $163.4 billion in direct medical costs over the course of the pandemic.

Seasonality of Respiratory Viral Infections

The seasonal cycle of respiratory viral diseases has been widely recognized for thousands of years, as annual epidemics of the common cold and influenza disease hit the human population like clockwork in the winter season in temperate regions. Moreover, epidemics caused by viruses such as severe acute respiratory syndrome coronavirus (SARS-CoV) and the newly emerging SARS-CoV-2 occur during the winter months. The mechanisms underlying the seasonal nature of respiratory viral infections have been examined and debated for many years. The two major contributing factors are the changes in environmental parameters and human behavior. Studies have revealed the effect of temperature and humidity on respiratory virus stability and transmission rates. More recent research highlights the importance of the environmental factors, especially temperature and humidity, in modulating host intrinsic, innate, and adaptive immune responses to viral infections in the respiratory tract. Here we review evidence of how outdoor and indoor climates are linked to the seasonality of viral respiratory infections. We further discuss determinants of host response in the seasonality of respiratory viruses by highlighting recent studies in the field.

Influenza vaccine effectiveness against influenza-associated hospitalization in children: A systematic review and meta-analysis

Vaccination remains the most effective way to prevent influenza infection, albeit vaccine effectiveness (VE) varies by year. Compared to other age groups, children and elderly adults have the highest risk of developing influenza-related complications and requiring hospitalization. During the last years, "test negative design" (TND) studies have been implemented in order to estimate influenza VE. The aim of this systematic review and meta-analysis was to summarize the findings of TND studies reporting influenza VE against laboratory-confirmed influenza-related hospitalization in children aged 6 months to 17 years. We searched the PubMed and Embase databases and identified 2615 non-duplicate studies that required detailed review. Among them, 28 met our inclusion criteria and we performed a random-effects meta-analysis using adjusted VE estimates. In our primary analysis, influenza vaccine offered significant protection against any type influenza-related hospitalization (57.48%; 95% CI 49.46-65.49). When we examined influenza VE per type and strain, VE was higher against H1N1 (74.07%; 95% CI: 54.85-93.30) and influenza B (50.87%; 95% CI: 41.75-59.98), and moderate against H3N2 (40.77%; 95% CI: 25.65-55.89). Notably, influenza vaccination offered higher protection in children who were fully vaccinated (61.79%; 95% CI: 54.45-69.13), compared to those who were partially vaccinated (33.91%; 95% CI: 21.12 - 46.69). Also, influenza VE was high in children less than 5 years old (61.71%; 95% CI: 49.29-74.12) as well as in children 6-17 years old (54.37%; 95% CI: 35.14-73.60). In conclusion, in the pediatric population, influenza vaccination offered significant protection against influenza-related hospitalization and complete annual vaccination should be encouraged.

Child Influenza Vaccination and Adult Work Loss: Reduced Sick Leave Use Only in Adults With Paid Sick Leave

INTRODUCTION

Children are a population of interest for influenza. They are at increased risk for severe influenza, comprise a substantial portion of influenza morbidity, and significantly contribute to its transmission in the household and subsequent parental work loss. The association between influenza vaccination and work loss prevention, however, has rarely been studied, and the sparse existing literature has very limited generalizability to U.S. adults, thus requiring better characterization.

METHODS

Using pooled National Health Interview Survey data (2013-2015, analyses conducted in 2018) nationally representative of working U.S. adults with household children (n=23,014), zero-inflated negative binomial regression examined the association of child influenza vaccination (exposure) with sick days (outcome) stratified by paid sick leave (no: n=10,741, yes: n=12,273).

RESULTS

Child influenza vaccination was associated with significantly lower sick day usage, but only among adults with paid sick leave (prevalence rate ratio=0.79, 95% CI=0.67, 0.93), equating to average annual sick days of 4.07 vs 3.29 in adults with unvaccinated versus vaccinated household children (difference=0.78 fewer days annually).

CONCLUSIONS

Influenza vaccination of children is associated with reduced sick leave in household adults, helping to keep the workforce healthy and reduce influenza's costly annual economic burden. This only occurred among adults with paid sick leave, however, which is distributed inequitably by income, education, gender, occupation, and race/ethnicity. Health in All Policies considers downstream health effects of social and economic policy; the failure of federal policy to ensure paid sick leave likely contributes to propagating influenza and health inequities.

Evaluation of the field-protective effectiveness of seasonal influenza vaccine among Korean children aged < 5 years during the 2014-2015 and 2015-2016 influenza seasons: a cohort study

BACKGROUND

A field effectiveness evaluation of the influenza vaccine among children younger than five years is important due to the high burden of influenza in this age group. The epidemiology of influenza virus changes rapidly each year. Moreover, the development of a new type of influenza vaccine is accelerating, necessitating a new field effectiveness evaluation.

METHODS

This multi-center, open-label cohort study was conducted in the northern part of Seoul from December 2014 to May 2015 and in Gyeong-gi Province from December 2015 to May 2016. The cohort comprised an influenza vaccinated group and non-vaccinated group. During the influenza seasons, we conducted influenza rapid tests and polymerase chain reaction assays for individuals with suspected influenza and checked for the presence of influenza virus. We calculated the influenza vaccine effectiveness by comparing the incidence rates of influenza between the vaccinated and non-vaccinated groups.

RESULTS

During the 2014-2015 season, the field effectiveness of the influenza vaccine was 38.4%. In particular, the vaccine effectiveness against type A influenza virus was 50.7%. During the 2015-2016 season, the vaccine effectiveness reached 23.8% and the vaccine effectiveness against type A influenza virus was 48.5%. The vaccine effectiveness against influenza B virus was markedly reduced in both seasons.

CONCLUSION

The influenza vaccine was supposed to be effective against influenza A, but may have a limited effectiveness against influenza B among Korean children aged < 5 years.

Live attenuated influenza vaccine for children

For many years, the UK seasonal influenza vaccination programme has been offered to people at higher risk from the complications of influenza infection, including those aged over 65 years and anyone aged over 6 months who is in a clinical risk group.¹ In 2012, the Joint Committee on Vaccination and Immunisation (JCVI) recommended extending seasonal influenza vaccination to children aged 2-16 years who are not in a clinical risk group.² In contrast to the vaccination programme for adults, which uses an injectable inactivated influenza vaccine, children are being offered a live attenuated influenza vaccine (LAIV) that is administered intranasally.² Here, we consider the evidence for the use of the intranasal influenza vaccine for children who are not in a clinical risk group.

Preventive Effects of Vitamin D on Seasonal Influenza A in Infants: A Multicenter, Randomized, Open, Controlled Clinical Trial

OBJECTIVES

This study aimed to evaluate the clinical efficacy and safety of vitamin D for preventing influenza A in 400 infants in a multicenter, randomized, open, controlled clinical trial.

METHODS

The infants were randomized into low-dose and high-dose vitamin D groups, and serum calcium, inorganic phosphorus and 25-hydroxyvitamin D levels were detected thrice in 4 months. Infants infected with influenza A were monitored for symptoms including fever, cough and wheezing. Pathogen levels and safety of vitamin D treatment were also evaluated.

RESULTS

Of 121 cases in total, 78 and 43 cases of influenza A infection occurred in the low-dose and high-dose vitamin D groups, respectively. There was a significant difference between the groups (χ = 14.6324, P = 0.0001). Among the cases of influenza infection, the median durations for fever, cough and wheezing were shorter in the high-dose vitamin D group than in the low-dose vitamin D group. The viral loads showed a downward trend in both groups and were significantly different between the groups at the second and third detections. Additionally, the incidences of adverse events and severe adverse events were very low and not significantly different between the 2 groups.

CONCLUSION

High-dose vitamin D (1200 IU) is suitable for the prevention of seasonal influenza as evidenced by rapid relief from symptoms, rapid decrease in viral loads and disease recovery. In addition, high-dose vitamin D is probably safe for infants.

Increasing Complexity of Vaccine Development

Vaccines already developed have been enormously successful. However, the development of future vaccines requires solution of a number of immunologic problems, including pathogen variability, short effector memory, evoking functional responses, and identification of antigens that generate protective responses. In addition, different populations may respond differently to the same vaccine because of genetic, age, or environmental factors.

Quantifying the economic value and quality of life impact of earlier influenza vaccination

BACKGROUND

Influenza vaccination is administered throughout the influenza disease season, even as late as March. Given such timing, what is the value of vaccinating the population earlier than currently being practiced?

METHODS

We used real data on when individuals were vaccinated in Allegheny County, Pennsylvania, and the following 2 models to determine the value of vaccinating individuals earlier (by the end of September, October, and November): Framework for Reconstructing Epidemiological Dynamics (FRED), an agent-based model (ABM), and FluEcon, our influenza economic model that translates cases from the ABM to outcomes and costs [health care and lost productivity costs and quality-adjusted life-years (QALYs)]. We varied the reproductive number (R0) from 1.2 to 1.6.

RESULTS

Applying the current timing of vaccinations averted 223,761 influenza cases, $16.3 million in direct health care costs, $50.0 million in productivity losses, and 804 in QALYs, compared with no vaccination (February peak, R0 1.2). When the population does not have preexisting immunity and the influenza season peaks in February (R0 1.2-1.6), moving individuals who currently received the vaccine after September to the end of September could avert an additional 9634-17,794 influenza cases, $0.6-$1.4 million in direct costs, $2.1-$4.0 million in productivity losses, and 35-64 QALYs. Moving the vaccination of just children to September (R0 1.2-1.6) averted 11,366-1660 influenza cases, $0.6-$0.03 million in direct costs, $2.3-$0.2 million in productivity losses, and 42-8 QALYs. Moving the season peak to December increased these benefits, whereas increasing preexisting immunity reduced these benefits.

CONCLUSION

Even though many people are vaccinated well after September/October, they likely are still vaccinated early enough to provide substantial cost-savings.

The Incidence of Respiratory Tract Infections in Vertically HIV-Infected Children in Lower Silesia in Poland and the Approach to Infection Prevention

Human immunodeficiency virus (HIV) is a risk factor associated with respiratory tract infections. However little is known about the prevalence of these infections in HIV-infected children in Poland. We investigated the incidence of respiratory tract infections in 26 HIV-infected children (aged 4-18, mean 10.3 years, including 17 girls) treated in our center and compared it with the age-matched control group of 70 children. The prevalence of chronic diseases and other factors such as cigarette smoking by household members or attending educational institutions were also taken into consideration. Among the HIV-infected children, 48 respiratory infections were observed, including 4 cases of pneumonia and 44 other respiratory infections for 312 person-month observations vs. 256 infections including 13 cases of pneumonia and 243 other respiratory infections for 840 person-month observations in the control group. Thus, incidence of respiratory infections per month was lower in HIV-infected children (14%) compared with the control group (29%), i.e., 0.14 95% CI (0.10-0.18) infections per month vs. 0.29 95% CI (0.26-0.32). There was no difference in the incidence of pneumonia. The lower incidence of respiratory infections in HIV-infected children may be explained by their avoiding sick people, taking influenza vaccination on the annual basis, and possibly antiviral medication. We conclude that the influence of modifiable environmental factors that reduce the risk of respiratory tract infections is more significant than the HIV infection itself.

Prevalence of antibodies against influenza A and B viruses in children in Germany, 2008 to 2010

The prevalence of influenza A and B virus-specific IgG was determined in sera taken between 2008 and 2010 from 1,665 children aged 0-17 years and 400 blood donors in Germany. ELISA on the basis of whole virus antigens was applied. Nearly all children aged nine years and older had antibodies against influenza A. In contrast, 40% of children aged 0-4 years did not have any influenza A virus-specific IgG antibodies. Eightysix percent of 0-6 year-olds, 47% of 7-12 year-olds and 20% of 13-17 year-olds were serologically naïve to influenza B viruses. By the age of 18 years, influenza B seroprevalence reached approximately 90%. There were obvious regional differences in the seroprevalence of influenza B in Germany. In conclusion, seroprevalences of influenza A and influenza B increase gradually during childhood. The majority of children older than eight years have basal immunity to influenza A, while comparable immunity against influenza B is only acquired at the age of 18 years. Children aged 0-6 years, showing an overall seroprevalence of 67% for influenza A and of 14% for influenza B, are especially at risk for primary infections during influenza B seasons.