Present and future of influenza prevention in pediatrics

Analysis of factors influencing influenza outbreaks in schools in Taicang City, China

Objective

This study aims to analyze the awareness of influenza prevention and control and the behavioral attitudes toward the work among parents and staff in schools in Taicang City and the impact of the vaccination rate among students on influenza outbreaks in schools. The findings can provide references for the development of effective control strategies for the spread of influenza.

Methods

An anonymous questionnaire survey was conducted on 10,962 students from 20 schools in Taicang City, with class as the unit of analysis. The survey investigated their awareness of influenza prevention and control, their attitudes, and the vaccination coverage.

Results

From January to June 2023, a total of 388 influenza outbreaks were reported in schools in Taicang City, involving 77 schools. There were 3,475 confirmed cases, with an average infection rate of 18.53%. In schools where influenza outbreaks had occurred, the incidence rate of those who received influenza vaccine was significantly lower than those who did not, and the vaccine protection rate was 28.22%. The knowledge awareness rates of "the main transmission routes of influenza" and "influenza vaccination can prevent influenza" among parents of students were 95.49 and 93.16%, respectively. The differences between schools involved in the epidemic and non-epidemic were statistically significant (p < 0.05). The correct attitudes of parents toward "actively reporting relevant symptoms to teachers when their children show symptoms" and "avoiding classes with diseases when their children are suspected to be sick" are 98.80 and 96.26%, respectively. The differences between schools with and without epidemic are statistically significant (p < 0.05). The correct attitudes of the class teacher toward "correct management and control of students with flu like symptoms in the class" and "taking correct prevention and control measures in the event of a flu epidemic in the class" were 89.36 and 92.55%, respectively. The differences between epidemic related and non-epidemic related classes were statistically significant (p < 0.05).

Conclusion

Enhance the knowledge level of influenza prevention and control among parents of students, Strengthening the training for class teachers in emergency response to infectious diseases and increasing vaccination coverage among students can effectively reduce the incidence of influenza and thereby the occurrence of cluster outbreaks in schools.

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.

Inflammatory responses to influenza vaccination at the extremes of age

Age affects the immune response to vaccination, with individuals at the extremes of age responding poorly. The initial inflammatory response to antigenic materials shapes the subsequent adaptive response and so understanding is required about the effect of age on the profile of acute inflammatory mediators. In this study we measured the local and systemic inflammatory response after influenza vaccination or infection in neonatal, young adult and aged mice. Mice were immunized intramuscularly with inactivated influenza vaccine with and without the adjuvant MF59 and then challenged with H1N1 influenza. Age was the major factor affecting the inflammatory profile after vaccination: neonatal mice had more interleukin-1α (IL-1α), C-reactive protein (CRP) and granulocyte-macrophage colony-stimulating factor (GMCSF), young adults more tumour necrosis factor-α (TNF), and elderly mice more interleukin-1 receptor antagonist (IL-1RA), IL-2RA and interferon-γ-induced protein 10 (IP10). Notably the addition of MF59 induced IL-5, granulocyte colony-stimulating factor (G-CSF), Keratinocyte Chemotractant (KC) and monocyte chemoattractant protein 1 (MCP1) in all ages of animals and levels of these cytokines correlated with antibody responses. Age also had an impact on the efficacy of vaccination: neonatal and young adult mice were protected against challenge, but aged mice were not. There were striking differences in the localization of the cytokine response depending on the route of exposure: vaccination led to a high serum response whereas intranasal infection led to a low serum response but a high lung response. In conclusion, we demonstrate that age affects the inflammatory response to both influenza vaccination and infection. These age-induced differences need to be considered when developing vaccination strategies for different age groups.

Prevention of influenza in healthy children

Healthy children are high transmitters of influenza and can experience poor influenza outcomes. Many questions remain about the efficacy and impect of preventive measures because most existing studies report imprecise proxies of influenza incidence, do not follow subjects throughout the entire influenza season and across multiple influenza seasons, or do not control for important factors such as timing of implementation and social contact patterns. Modeling and simulation are key methodologies to answer questions regarding influenza prevention. While vaccination may be the most efficacious existing intervention, variations in circulating strains and children's immune systems keep current vaccines from being fully protective, necessitating further clinical and economic studies and technology improvements. Hand hygiene appears to be an important adjunct but improving compliance, standardizing regimens and quantifying its impact remain challenging. Future studies should help better define the specific indications and circumstances for antiviral use and the role of nutritional supplements and nonpharmaceutical interventions.

Recurrent lower respiratory tract infections in children: a practical approach to diagnosis

Many children are affected by recurrent lower respiratory tract infections (LRTIs), but the majority of them do not suffer from serious lung or extrapulmonary disease. The challenge for clinicians is to distinguish the recurrent RTIs with self-limiting or minor problems from those with underlying disease. The aim of this review is to describe a practical approach to children with recurrent LRTIs that limits unnecessary, expensive and time-consuming investigations. The children can be divided into three groups on the basis of their personal and family history and clinical findings: 1) otherwise healthy children who do not need further investigations; 2) those with risk factors for respiratory infections for whom a wait-and-see approach can be recommended; and 3) those in whom further investigations are mandatory. However, regardless of the origin of the recurrent LRTIs, it is important to remember that prevention by means of vaccines against respiratory pathogens (i.e. type b Haemophilus influenzae, pertussis, pneumococcal and influenza vaccines) can play a key role.

Impact of vitamin D administration on immunogenicity of trivalent inactivated influenza vaccine in previously unvaccinated children

As vitamin D (VD) has a significant regulatory effect on innate and adaptive immunity, the aim of this prospective, randomized, single-blinded, placebo-controlled study was to measure the impact of VD administration on the immune response to trivalent influenza vaccination (TIV). A total of 116 children (61 males, 52.6%; mean age 3.0 ± 1.0 y) with a history of recurrent acute otitis media (AOM), who had not been previously vaccinated against influenza, were randomized to receive daily VD 1,000 IU or placebo by mouth for four months. All of them received two doses of TIV (Fluarix, GlaxoSmithKline Biologicals) one month apart, with the first dose administered when VD supplementation was started. There was no difference in seroconversion or seroprotection rates, or antibody titers, in relation to any of the three influenza vaccine antigens between the VD and placebo groups, independently of baseline and post-treatment VD levels. The safety profile was also similar in the two groups. These data indicate that the daily administration of VD 1,000 IU for four months from the time of the injection of the first dose of TIV does not significantly modify the antibody response evoked by influenza vaccine.

Efficacy and safety of influenza vaccination in children with asthma

The mean global prevalence of asthma among children is approximately 12%, making it the most common chronic disease in children. Influenza infection has been associated with complications such as exacerbations of wheezing and asthma, increased airway hyper-reactivity and hospitalization. Although influenza vaccination is recommended for asthmatic patients by all health authorities, vaccination coverage remains significantly lower than expected and is lowest of all in children. Compliance is affected by the uncertainty of parents and physicians concerning the clinical risk of influenza in asthmatic subjects, the benefits of influenza vaccination in preventing asthma exacerbations and the safety of immunization. The aim of this review is to analyze the rationale for using influenza vaccine, discuss the relationship between influenza and the severity of asthmatic episodes and document the efficacy and safety of influenza vaccination in the pediatric asthmatic population.

Can infants be protected by means of maternal vaccination?

The administration of vaccines is not usually recommended in pregnant women because of a fear of severe adverse events for the fetus. However, contraindication to vaccination applies only to vaccines based on live attenuated viruses for the theoretical possibility that they might infect the fetus. In contrast, the use of several inactivated vaccines is useful and recommended. As a result of the transplacental passage of antibodies, maternal immunization can reduce the risk of vaccine-preventable diseases that may occur in the first months of life before the start or completion of the suggested vaccination schedule. One of the best examples is vaccination against influenza that can protect pregnant women from a disease that can lead to hospitalization and death in a significantly higher number of cases than in the general population and can induce protective specific antibody levels as well as being effective in infants in the first months of life. Other examples are vaccinations against tetanus, pertussis, pneumococcal infections and Haemophilus influenzae type b infection. This review analyses the advantages and limitations of maternal immunization as revealed by experience and the main publications.

Impact of viral infections in children with community-acquired pneumonia: results of a study of 17 respiratory viruses

Please cite this paper as: Esposito et al. (2012) Impact of viral infections in children with community‐acquired pneumonia: results of a study of 17 respiratory viruses. Influenza and Other Respiratory Viruses DOI: 10.1111/j.1750‐2659.2012.00340.x.

Background  Little is known about the prevalence of viral infections in children with community‐acquired pneumonia (CAP).

Objectives  To describe the clinical and virological data collected from children with radiographically confirmed CAP in whom 17 respiratory viruses were sought in respiratory secretion samples during the acute phase of the disease.

Patients and methods  The study involved 592 children with radiographically confirmed CAP whose respiratory secretion samples were tested using the Luminex xTAG Respiratory Virus Panel Fast assay, which simultaneously detects influenza A virus, influenza B virus, respiratory syncytial virus (RSV)‐A and ‐B, parainfluenzavirus‐1, ‐2, ‐3, and ‐4, adenovirus, human metapneumovirus, coronaviruses 229E, NL63, OC43, and HKU1, enterovirus/rhinovirus, and bocavirus. A real‐time PCR assay was used to identify the rhinovirus in the enterovirus/rhinovirus‐positive samples.

Results  A total of 435 children (73·5%) were positive for at least one virus: the most frequently detected was RSV, which was found in 188 (31·7%), followed by rhinovirus (n = 144, 24·3%), bocavirus (n = 60, 10·1%), influenza viruses (n = 57, 9·6), and hMPV (n = 49, 8·2%). Viral co‐infections were found in 117 children (19·7% of the enrolled children; 26·9% of those with viral infections). Marginal differences were found between the infections owing to a single virus. Co‐infections showed radiographic evidence of alveolar pneumonia significantly more frequently than single infections (OR 1·72, 95% CI 1·05–2·81).

Conclusions  The findings of this study highlight the importance of respiratory viruses (mainly RSV and rhinovirus) in children with CAP and show the characteristics of both the single infections and co‐infections associated with the disease.

Clinical and socioeconomic impact of pediatric seasonal and pandemic influenza

Influenza is frequent among otherwise healthy day-care and school-aged children. Recent studies have demonstrated its significant effect on various outcome factors, including significantly more school and parental work absenteeism, and secondary illnesses among family members. Other studies have shown that the potential benefit of vaccinating children against influenza extends to other members of their families, thus supporting earlier economic modeling analyses of immunization programs. Although there are some differences in the clinical and socio-economic impact of seasonal and pandemic influenza, the benefits of vaccination are similar in both cases. The vaccination of otherwise healthy children may significantly reduce direct and indirect influenza-related costs, which supports the recommendation to make wider use of influenza vaccine in healthy children of any age in order to reduce the burden of infection on the community.

Immunogenicity, safety and tolerability of MF59-adjuvanted seasonal influenza vaccine in children with juvenile idiopathic arthritis

In order to evaluate the immunogenicity, safety, and tolerability of the MF-59 adjuvanted seasonal influenza vaccine in children and adolescents with juvenile idiopathic arthritis (JIA) treated with different anti-rheumatic drugs, 60 pediatric patients with JIA (30 treated with disease-modifying anti-rheumatic drugs [DMARDs] and 30 with etanercept) were compared with 30 healthy controls of similar gender and age. All of the patients received a single dose of the MF59-adjuvanted seasonal influenza vaccine (Fluad, Siena, Italy). Immunogenicity was assessed at baseline, and 1 and 3 months post-vaccination; safety and tolerability were also evaluated during the study period. The JIA patients treated with etanercept showed significantly lower geometric mean titres (GMTs) against the A/H1N1 strain than those treated with DMARDs (p<0.05) and the healthy controls (p<0.05), who had similar GMTs. The etanercept-treated JIA patients also showed a significant reduction in GMTs against the A/H1N1 and A/H3N2 strains from 1 to 3 months after vaccination (p<0.05). Furthermore, their seroconversion and seroprotection rates, and B antigen GMTs, were all significantly lower than those of the subjects in the other two groups (p<0.05). The safety and tolerability of the vaccine were good and similar between the groups. The results of this study indicate a reduced immune response to MF59-adjuvanted seasonal influenza vaccine in JIA children and adolescents treated with etanercept in comparison with those treated with DMARDs and healthy controls. The safety and tolerability of the vaccine appeared to be good in all of the study population.

Impact of pandemic A/H1N1/2009 influenza on children and their families: comparison with seasonal A/H1N1 and A/H3N2 influenza viruses

OBJECTIVES

To make a direct comparison between the total burden of pandemic influenza and that of other seasonal influenza A viral subtypes in otherwise healthy children.

METHODS

The total clinical and socioeconomic burden of pandemic A/H1N1/2009 influenza was compared with that of seasonal influenza A viral subtypes in 389 otherwise healthy children with A/H1N1/2009, 126 with seasonal A/H1N1 and 486 with seasonal A/H3N2 infection referred to the Emergency Room and hospitalised in the in-patient units of a large, university-based paediatric hospital. Influenza diagnosis was confirmed by real-time polymerase chain reaction.

RESULTS

Regardless of age or gender, the variables significantly associated with pandemic A/H1N1/2009 and seasonal A/H3N2 infection were a diagnosis of lower respiratory tract infection upon clinical presentation, the need for hospitalisation, hospitalisation for ≥7 days, school absences of ≥7 days, the need for aerosol therapy, the household development of a disease similar to that of the infected child, and the need for additional household medical visits and antibiotic prescriptions (p < 0.001). A longer period of hospitalisation and lost school days seemed to be associated with pandemic A/H1N1/2009 infection (p < 0.01).

CONCLUSIONS

Perceived symptom severity and the risk of serious outcomes are similar in children with influenza due to pandemic A/H1N1/2009 or seasonal A/H3N2 influenza, but both of these viruses seem to have a greater clinical and socioeconomic impact than seasonal A/H1N1 virus, regardless of the patients' age or gender.