The underrecognized burden of influenza in young children

Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices, United States, 2021-22 Influenza Season

This report updates the 2020-21 recommendations of the Advisory Committee on Immunization Practices (ACIP) regarding the use of seasonal influenza vaccines in the United States (MMWR Recomm Rep 2020;69[No. RR-8]). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. For each recipient, a licensed and age-appropriate vaccine should be used. ACIP makes no preferential recommendation for a specific vaccine when more than one licensed, recommended, and age-appropriate vaccine is available. During the 2021-22 influenza season, the following types of vaccines are expected to be available: inactivated influenza vaccines (IIV4s), recombinant influenza vaccine (RIV4), and live attenuated influenza vaccine (LAIV4).The 2021-22 influenza season is expected to coincide with continued circulation of SARS-CoV-2, the virus that causes COVID-19. Influenza vaccination of persons aged ≥6 months to reduce prevalence of illness caused by influenza will reduce symptoms that might be confused with those of COVID-19. Prevention of and reduction in the severity of influenza illness and reduction of outpatient visits, hospitalizations, and intensive care unit admissions through influenza vaccination also could alleviate stress on the U.S. health care system. Guidance for vaccine planning during the pandemic is available at https://www.cdc.gov/vaccines/pandemic-guidance/index.html. Recommendations for the use of COVID-19 vaccines are available at https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/covid-19.html, and additional clinical guidance is available at https://www.cdc.gov/vaccines/covid-19/clinical-considerations/covid-19-vaccines-us.html.Updates described in this report reflect discussions during public meetings of ACIP that were held on October 28, 2020; February 25, 2021; and June 24, 2021. Primary updates to this report include the following six items. First, all seasonal influenza vaccines available in the United States for the 2021-22 season are expected to be quadrivalent. Second, the composition of 2021-22 U.S. influenza vaccines includes updates to the influenza A(H1N1)pdm09 and influenza A(H3N2) components. U.S.-licensed influenza vaccines will contain hemagglutinin derived from an influenza A/Victoria/2570/2019 (H1N1)pdm09-like virus (for egg-based vaccines) or an influenza A/Wisconsin/588/2019 (H1N1)pdm09-like virus (for cell culture-based and recombinant vaccines), an influenza A/Cambodia/e0826360/2020 (H3N2)-like virus, an influenza B/Washington/02/2019 (Victoria lineage)-like virus, and an influenza B/Phuket/3073/2013 (Yamagata lineage)-like virus. Third, the approved age indication for the cell culture-based inactivated influenza vaccine, Flucelvax Quadrivalent (ccIIV4), has been expanded from ages ≥4 years to ages ≥2 years. Fourth, discussion of administration of influenza vaccines with other vaccines includes considerations for coadministration of influenza vaccines and COVID-19 vaccines. Providers should also consult current ACIP COVID-19 vaccine recommendations and CDC guidance concerning coadministration of these vaccines with influenza vaccines. Vaccines that are given at the same time should be administered in separate anatomic sites. Fifth, guidance concerning timing of influenza vaccination now states that vaccination soon after vaccine becomes available can be considered for pregnant women in the third trimester. As previously recommended, children who need 2 doses (children aged 6 months through 8 years who have never received influenza vaccine or who have not previously received a lifetime total of ≥2 doses) should receive their first dose as soon as possible after vaccine becomes available to allow the second dose (which must be administered ≥4 weeks later) to be received by the end of October. For nonpregnant adults, vaccination in July and August should be avoided unless there is concern that later vaccination might not be possible. Sixth, contraindications and precautions to the use of ccIIV4 and RIV4 have been modified, specifically with regard to persons with a history of severe allergic reaction (e.g., anaphylaxis) to an influenza vaccine. A history of a severe allergic reaction to a previous dose of any egg-based IIV, LAIV, or RIV of any valency is a precaution to use of ccIIV4. A history of a severe allergic reaction to a previous dose of any egg-based IIV, ccIIV, or LAIV of any valency is a precaution to use of RIV4. Use of ccIIV4 and RIV4 in such instances should occur in an inpatient or outpatient medical setting under supervision of a provider who can recognize and manage a severe allergic reaction; providers can also consider consulting with an allergist to help identify the vaccine component responsible for the reaction. For ccIIV4, history of a severe allergic reaction (e.g., anaphylaxis) to any ccIIV of any valency or any component of ccIIV4 is a contraindication to future use of ccIIV4. For RIV4, history of a severe allergic reaction (e.g., anaphylaxis) to any RIV of any valency or any component of RIV4 is a contraindication to future use of RIV4. This report focuses on recommendations for the use of vaccines for the prevention and control of seasonal influenza during the 2021-22 influenza season in the United States. A brief summary of the recommendations and a link to the most recent Background Document containing additional information are available at https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html. These recommendations apply to U.S.-licensed influenza vaccines used according to Food and Drug Administration-licensed indications. Updates and other information are available from CDC's influenza website (https://www.cdc.gov/flu); vaccination and health care providers should check this site periodically for additional information.

A M2 protein-based universal influenza vaccine containing Advax-SM adjuvant provides newborn protection via maternal or neonatal immunization

BACKGROUND

Despite newborns being at increased risk of serious influenza infection, influenza vaccines are currently not recommended for use in infants under 6 months of age. We therefore sought to evaluate the protective efficacy in mice of an M2-based influenza vaccine (CapM2e) formulated with Advax-SM adjuvant. Vaccine protection was assessed via both passive maternal immunization and direct neonatal immunization.

METHODS

For maternal transfer studies, female mice were immunized 1 week before and after mating. Blood was collected from both mother and offspring during weaning and pups were challenged when they reached 3 weeks of age with lethal doses of H1N1 and homologous reassortment influenza strain H3N2 with conserved M2. For direct immunization studies, newborns were immunized at 1 and 3 weeks of age and blood was collected prior to challenge at 4 weeks of age.

RESULTS

Maternal immunization with CapM2e + Advax-SM vaccine induced high maternal M2e antibody levels that were passively transferred to their offspring and provided them with protection against both H1N1 and H3N2 influenza strains when challenged at 3 weeks of age. When used for direct immunization of neonatal mice, CapM2e + Advax-SM vaccine similarly induced high serum M2e antibody levels and protected against H1N1 and H3N2 influenza challenges with protection associated with inhibition of virus replication with a significant reduction in lung virus load in immunized pups.

CONCLUSION

CapM2e + Advax-SM vaccine could be useful for protecting newborns against diverse influenza A strains, with opportunities to achieve protection by passive maternal immunization or active neonatal immunization. This data supports further development of this promising M2e-based vaccine candidate.

Understanding Antibody Responses in Early Life: Baby Steps towards Developing an Effective Influenza Vaccine

The immune system of young infants is both quantitatively and qualitatively distinct from that of adults, with diminished responsiveness leaving these individuals vulnerable to infection. Because of this, young infants suffer increased morbidity and mortality from respiratory pathogens such as influenza viruses. The impaired generation of robust and persistent antibody responses in these individuals makes overcoming this increased vulnerability through vaccination challenging. Because of this, an effective vaccine against influenza viruses in infants under 6 months is not available. Furthermore, vaccination against influenza viruses is challenging even in adults due to the high antigenic variability across viral strains, allowing immune evasion even after induction of robust immune responses. This has led to substantial interest in understanding how specific antibody responses are formed to variable and conserved components of influenza viruses, as immune responses tend to strongly favor recognition of variable epitopes. Elicitation of broadly protective antibody in young infants, therefore, requires that both the unique characteristics of young infant immunity as well as the antibody immunodominance present among epitopes be effectively addressed. Here, we review our current understanding of the antibody response in newborns and young infants and discuss recent developments in vaccination strategies that can modulate both magnitude and epitope specificity of IAV-specific antibody.

An R848-Conjugated Influenza Virus Vaccine Elicits Robust Immunoglobulin G to Hemagglutinin Stem in a Newborn Nonhuman Primate Model

Eliciting broadly protective antibodies is a critical goal for the development of more effective vaccines against influenza. Optimizing protection is of particular importance in newborns, who are highly vulnerable to severe disease following infection. An effective vaccination strategy for this population must surmount the challenges associated with the neonatal immune system as well as mitigate the inherent immune subdominance of conserved influenza virus epitopes, responses to which can provide broader protection. Here, we show that prime-boost vaccination with a TLR7/8 agonist (R848)-conjugated influenza A virus vaccine elicits antibody responses to the highly conserved hemagglutinin stem and promotes rapid induction of virus neutralizing stem-specific antibodies following viral challenge. These findings support the efficacy of R848 as an effective adjuvant for newborns and demonstrate its ability to enhance antibody responses to subdominant antigenic sites in this at-risk population.

Respiratory Virus Surveillance in Infants across Different Clinical Settings

OBJECTIVES

We aimed to evaluate the distribution, clinical presentations and severity of common acute respiratory infections (ARI) viruses in infants across 3 clinical settings.

STUDY DESIGN

In a prospective virus surveillance study, infants under 1 year with fever and/or respiratory symptoms were enrolled from outpatient, emergency department, and inpatient settings from December 16, 2019 through April 30, 2020. Demographic and clinical characteristics were collected through parent/guardian interviews, medical chart abstractions, and follow-up surveys. Nasal swabs were collected and tested for viruses using quantitative reverse-transcription polymerase chain reaction.

RESULTS

We enrolled 366 infants and tested nasal swabs on 360 (98%); median age was 6.3 months, 50% male. In total, 295 (82%) had at least 1 virus detected; rhinovirus/enterovirus (RV/EV; 42%), respiratory syncytial virus (RSV; 34%), and influenza (15%) were the most common. RSV was the most frequently detected virus in the inpatient (63%) and emergency department (37%) settings, and RV/EV was most frequently detected virus in the outpatient setting (54%). RSV-positive infants had a lower median age (4.9 months) and were more likely to have respiratory distress, and RV/EV-positive infants were less likely to have respiratory distress. Influenza-positive infants had a higher median age (8 months) and were more likely to have systemic symptoms. RSV infection and younger age were associated with higher odds of hospitalization in multivariable logistic regression.

CONCLUSIONS

Across 3 clinical settings, and combining virologic, patient, and health-system information, our results highlight the burden of viral ARI among infants. Overall, RSV, RV/EV, and influenza were most commonly detected, with RSV having the highest disease severity.

Influence of commissioned provider type and deprivation score on uptake of the childhood flu immunization

BACKGROUND

Since 2015/16 the UK seasonal influenza immunization programme has included children aged 5 and 6 years. In the South West of England school-based providers, GPs or community pharmacies were commissioned to deliver the vaccine depending on the locality. We aimed to assess variation in vaccine uptake in relation to the type of commissioned provider, and levels of socioeconomic deprivation.

METHODS

Data from the South West of England (2015-16 season) were analysed using multilevel logistic regression to assess variation in vaccine uptake by type of commissioned provider, allowing for clustering of children within delivery sites.

RESULTS

Overall uptake in 5 and 6 year olds was 34.3% (37 555/109 404). Vaccine uptake was highest when commissioned through school-based programmes 50.2% (9983/19 867) and lowest when commissioned through pharmacies, 23.1% (4269/18 479). Delivery through schools resulted in less variation by site and equal uptake across age groups, in contrast to GP and pharmacy delivery for which uptake was lower among 6 year olds. Vaccine uptake decreased with increasing levels of deprivation across all types of commissioned provider.

CONCLUSION

School-based programmes achieve the highest and most consistent rates of childhood influenza vaccination. Interventions are still needed to promote more equitable uptake of the childhood influenza vaccine.

Assessing the impact of acute respiratory illnesses on the risk of subsequent respiratory illness

BACKGROUND

Whether acute respiratory illnesses (ARIs), often associated with virus detection, are associated with lower risk for subsequent ARI remains unclear. We assessed the association between symptomatic ARI and subsequent ARI in young children.

METHODS

In a prospective cohort of Peruvian children <3 years, we examined the impact of index ARI on subsequent ARI risk. Index ARI were matched with ≤3 asymptomatic observations and followed over 28 days. We compared risk of subsequent ARI between groups using conditional logistic regression adjusting for several covariates, accounting for repeat observations from individual children.

RESULTS

Among 983 index ARI, 339 (34%) had an ARI event during follow-up, compared with 876/2826 (31%) matched asymptomatic observations. We found no significant association of index ARI and subsequent ARI risk during follow-up overall (aOR 1.10, 95% CI 0.98, 1.23) or when limited to index ARI with respiratory viruses detected (aOR 1.03, 95% CI 0.86, 1.24). Similarly, when the outcome was limited to ARI in which viruses were detected, no significant association was seen (aOR 1.05, 95% CI 0.87, 1.27).

DISCUSSION

ARIs were not associated with short-term protection against subsequent ARI in these children. Additional longitudinal studies are needed to understand drivers of recurrent ARI in young children.

The burden of Respiratory Syncytial Virus (RSV) infection in the Middle East and North Africa (MENA) region across age groups: A systematic review

Respiratory Syncytial Virus (RSV) is a common respiratory virus that generally causes a mild illness in children and adults or severe symptoms with complications in infants and the elderly, particularly in the presence of underlying comorbidities. While epidemiological data about this virus are available globally, data from the Middle East and North Africa (MENA) region are still scarce. For this reason, we conducted a systematic review to determine the burden of RSV disease in the MENA region by searching the available literature up until September 2018. A total of 1242 studies were retrieved of which 90 were included in the review. Most of the included studies were conducted in subjects aged 0-18 years with the majority being in children below 3 years of age, while only 2 studies included exclusively adults above 18 years of age. RSV infection rates varied greatly between different studies on hospitalized subjects and ranged between 4% and 82%, while the range was smaller in studies on outpatient subjects (between 6% and 36%). When calculating the RSV infection rates in the hospitalized subjects with different inclusion criteria, we found that it was 19%, 70%, and 33% among subjects admitted with Acute Respiratory Infections (ARIs), Acute Lower Respiratory Infections (ALRIs), and bronchiolitis, respectively. RSV infections were most common during the winter season. With regards to complications, intensive care unit admissions ranged between 1% and 15%, while the need for mechanical ventilation ranged between 1% and 10%. The overall RSV related mortality rate across all age groups in studies included in our review was 1.9%. This review identifies several limitations in the existing data and under-representation of the adult population. Future studies should be providing more evidence on the RSV burden in adults and children with comorbidities in order to better assess the potential impact of future preventive strategies in the MENA region.

Influenza hospitalizations in children under 1 year old in Spain: the importance of maternal immunization

This study estimates the burden of influenza in infants up to 12 months of age in Spain over 8 seasons (2009/10-2016/17). The survey was conducted by reviewing the Spanish Surveillance System for Hospital Data. Over the eight seasons, 5,618 hospital admissions were recorded for patients younger than 12 months that included codes related to influenza in any diagnostic position (487-488 ICD-9-CM and J9, J10 and J11 CIE 10). In total, 2,363 admissions (42.1%) were female patients whose median age was 3.05 months. Patients younger than 6 months accounted for 3,856 admissions (68.6%). Among them, 59.2% were male, and 40.8% were female (p < .05). Overall, 37.1% (2,084 patients) were younger than 2 months. The hospitalization rate for the entire period studied was 156.09 admissions per 100,000 children under 12 months of age (95% CI: 152.4-160.6). The average duration of hospitalization was 6.6 days (95% CI: 6.4-6.8). Eighteen deaths were recorded for hospitalized patients over the entire period. Of these, 12 patients (66.7%) were younger than 6 months. There is a significant burden of influenza disease in children under 1 year of age in Spain, mainly in children under 6 months of age. Improvements to prevention strategies through increased vaccination coverage in family environments and vaccination strategies involving pregnant woman can contribute decisively and effectively to reducing these hospitalizations.

Oseltamivir treatment of influenza A and B infections in infants

Background

Oseltamivir treatment is currently the only way of managing influenza in young infants for whom influenza vaccines are not licensed, but little data exist on the effectiveness of the treatment in this age group.

Methods

In a prospective study, we enrolled 431 newborn infants and followed them up for 10 months during their first respiratory season (September 2017‐June 2018). During each respiratory illness, we examined the infants and obtained nasopharyngeal specimens for determination of the viral etiology. Infants with influenza were re‐examined at short intervals, and additional nasopharyngeal specimens were obtained at each visit for measuring the viral load. All infants with symptoms <48 hours received oseltamivir treatment. The parents filled out daily symptom diaries.

Results

Among 23 infants with influenza A, the mean total duration of illness in oseltamivir recipients was 82.1 hours, compared with 253.5 hours in infants without treatment (P = .0003). For infants with influenza B, the corresponding durations were 110.0 and 173.9 hours, respectively (P = .03). In infants with influenza A, total symptom scores were significantly lower in oseltamivir‐treated infants at all time points between days 3 and 11 after the onset of therapy. In most children with either influenza A or B, viral antigen concentrations declined rapidly within 1‐2 days after the initiation of oseltamivir treatment.

Conclusions

Oseltamivir treatment of infants with influenza rapidly decreased the viral load in nasopharyngeal secretions and shortened the duration and severity of symptoms. The clinical effectiveness of oseltamivir appeared to be greater against influenza A than against influenza B infections.

Association Between the Use of Antibiotics, Antivirals, and Hospitalizations Among Patients With Laboratory-confirmed Influenza

BACKGROUND

Clinicians may prescribe antibiotics to influenza patients at high risk for bacterial complications. We explored the association between antibiotics, antivirals, and hospitalization among people with influenza.

METHODS

A retrospective cohort study of patients with confirmed influenza with encounters during January 2011-January 2019 was conducted using data from the Veterans Affairs Informatics and Computing Infrastructure (VINCI). We compared inpatient hospitalizations (all-cause and respiratory) within 30 days of influenza diagnosis between 4 patient cohorts: (1) no treatment (n = 4228); (2) antibiotic only (n = 671); (3) antiviral only (n = 6492); and (4) antibiotic plus antiviral (n = 1415). We estimated relative risk for hospitalization using Poisson generalized linear model and robust standard errors.

RESULTS

Among 12 806 influenza cases, most were white men (mean age, 57-60 years). Those with antivirals only, antibiotic plus antiviral, and antibiotics only all had a statistically significant lower risk of all-cause and respiratory hospitalization compared to those without treatment. Comparing the antibiotic plus antiviral cohort to those who were prescribed an antiviral alone, there was a 47% lower risk for respiratory hospitalization (relative risk, 0.53 [95% confidence interval, .31-.94]), and no other statistical differences were detected.

CONCLUSIONS

Those prescribed an antiviral, antibiotic, or both had a lower risk of hospitalization within 30 days compared to those without therapy. Furthermore, intervention with both an antibiotic and antiviral had a lower risk of respiratory hospitalization within 30 days compared to those with an antiviral alone. Importantly, the absolute magnitude of decreased risk with antibiotic plus antiviral therapy is small and must be interpreted within the context of the overall risk of antibiotic usage.

Association between asthma and influenza vaccine uptake among US adolescents: a retrospective survey study

OBJECTIVE

Despite longstanding recommendations for children with asthma to receive the influenza vaccine, vaccine uptake in this population remains low. We used the nationally representative National Immunization Survey-Teen to analyze the impact of asthma on adolescent influenza vaccination rates.

METHODS

Adolescents ages 13-17 years with provider-reported data on vaccine coverage were included in the analysis. The primary outcome was being up-to-date on influenza vaccination, defined as receiving the seasonal influenza vaccine in at least one of the past 3 years, and was analyzed using logistic regression. Asthma was defined by parent report of whether the adolescent has ever been told by a health professional that he or she has asthma. Data were collected in 2016-2017 and analyzed in 2020.

RESULTS

Of 36,655 adolescents in the analytic sample (mean age 15 years, 49% female), 55% were up-to-date on influenza vaccination, and 21% had been diagnosed with asthma. On bivariate analysis, vaccination was more common among adolescents who had been diagnosed with asthma compared to those who were not (60% vs. 53%, P < 0.001). On multivariable analysis, asthma diagnosis was associated with greater likelihood of being up-to-date on seasonal influenza vaccination (adjusted odds ratio: 1.29; 95% confidence interval: 1.22, 1.36; P < 0.001).

CONCLUSIONS

Seasonal influenza vaccination rates remain low among adolescents. Despite concerns about vaccine effectiveness in children with asthma, this diagnosis was associated with increased likelihood of influenza vaccination, possibly in relation to increased health care use (and exposure to vaccine encouragement) among adolescents with asthma.

A Reduced Dose Whole Virion Aluminum Adjuvanted Seasonal Influenza Vaccine Is Immunogenic, Safe, and Well Tolerated in Pediatric Patients

BACKGROUND

Data suggest that pediatric patients might react differently to influenza vaccination, both in terms of immunity and side effects. We have recently shown that using a whole virion vaccine with aluminum phosphate adjuvants, reduced dose vaccines containing 6 µg of viral hemagglutinin (HA) per strain are immunogenic, and well tolerated in adult and elderly patients. Here we show the results of a multicenter clinical trial of pediatric patients, using reduced doses of a new, whole virion, aluminum phosphate adjuvanted vaccine (FluArt, Budapest, Hungary).

METHODS

A total of 120 healthy volunteers were included in two age groups (3-11 years, receiving 3 µg of HA per strain, and 12-18 years, receiving 6 µg of HA per strain). We used hemagglutination inhibition testing to assess immunogenicity, based on EMA and FDA licensing criteria, including post/pre-vaccination geometric mean titer ratios, seroconversion and seropositivity rates. Safety and tolerability were assessed using CHMP guidelines.

RESULTS

All subjects entered the study and were vaccinated (ITT population). All 120 subjects attended the control visit on Day 21 (PP population). All immunogenicity licensing criteria were met in both age groups for all three vaccine virus strains. No serious adverse events were detected and the vaccine was well tolerated by both age groups.

DISCUSSION

Using a whole virion vaccine and aluminum phosphate adjuvants, a reduction in the amount of the viral hemmaglutinin is possible while maintaining immunogenicity, safety and tolerability in pediatric and adolescent patients.

Sociodemographic and health-related determinants of seasonal influenza vaccination in pregnancy: A systematic review and meta-analysis of the evidence since 2000

INTRODUCTION

Vaccination is considered to be the most practical and effective preventative measure against influenza. It is highly recommended for population subgroups most at risk of developing complications, including pregnant women. However, seasonal influenza vaccine uptake remains suboptimal among pregnant women, even in jurisdictions with universal vaccination. We summarized the evidence on the determinants of seasonal influenza vaccine uptake during pregnancy to better understand factors that influence vaccine uptake among pregnant women.

MATERIAL AND METHODS

We systematically searched MEDLINE, Embase and CINAHL from January 2000 to February 2020 for publications in English reporting on sociodemographic and/or health-related determinants of seasonal influenza vaccine uptake during pregnancy. Two reviewers independently included studies. One reviewer extracted data and assessed study quality, and another reviewer checked extracted data and study quality assessments for errors. Disagreements were resolved through consensus, or a third reviewer. We meta-analyzed using the inverse variance, random-effects method, and reported the odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

From 1663 retrieved citations, we included 36 studies. The following factors were associated with increased seasonal influenza vaccine uptake: Older age (20 studies: OR 1.13, 95% CI 1.07-1.20), being nulliparous (13 studies: OR 1.26, 95% CI 1.15-1.38), married (8 studies: OR 1.11, 95% CI 1.07-1.15), employed (4 studies: OR 1.13, 95% CI 1.02-1.24), a non-smoker (8 studies: OR 1.25, 95% CI 1.04-1.51) and having prenatal care (3 studies: OR 3.36, 95% CI 2.25-5.02), a chronic condition (6 studies: OR 1.30, 95% CI 1.17-1.44), been previously vaccinated (9 studies: OR 4.88, 95% CI 3.14-7.57) and living in a rural area (9 studies: OR 1.09, 95% CI 1.05-1.14). Compared with being black, being white was also associated with increased seasonal influenza vaccine uptake (11 studies: OR 1.30, 95% CI 1.20-1.41).

CONCLUSIONS

The evidence suggests that several sociodemographic and health-related factors may determine seasonal influenza vaccination in pregnancy, and that parity, history of influenza vaccination, prenatal care and comorbidity status may be influential.

Clinical Characteristics and CT Findings in 148 Non-COVID-19 Influenza-Like Illness Cases: A Retrospective Control Study

Background: This study was to collect clinical features and computed tomography (CT) findings of Influenza-Like Illness (ILI) cases, and to evaluate the correlation between clinical data and the abnormal chest CT in patients with the Influenza-Like Illness symptoms. Methods: Patients with the Influenza-Like Illness symptoms who attended the emergency department of The Six Medical Center of The PLA General Hospital from February 10 to April 1, 2020 were enrolled. Clinical and imaging data of the enrolled patients were collected and analyzed. The association between clinical characteristics and abnormal chest CT was also analyzed. Results: A total of 148 cases were enrolled in this study. Abnormalities on chest CT were detected in 61/148 (41.2%) patients. The most common abnormal CT features were as follows: patchy consolidation 22/61(36.1%), ground-glass opacities 21/61(34.4%), multifocal consolidations 17/61(27.9%). The advanced age and underlying diseases were significantly associated with abnormal chest CT. Conclusions: Abnormal chest CT is a common condition in Influenza-Like Illness cases. The presence of advanced age and concurrent underlying diseases is significantly associated with abnormal chest CT findings in patients with ILI symptoms. The chest CT characteristic of ILI is different from the manifestation of COVID-19 infection, which is helpful for differential diagnosis.

A Retrospective observational cohort study of the effect of antenatal influenza vaccination on birth outcomes in Cape Town, South Africa, 2015-2016

Background

There are conflicting data concerning the impact of antenatal influenza vaccination on birth outcomes including low birthweight (LBW), preterm birth, small for gestational age (SGA), and stillbirth.

Methods

We conducted a retrospective observational cohort study of infants born to women residing in Mitchells Plain, Cape Town. Infants were born at 4 health facilities during May 28 – December 31, 2015 and April 15 – December 31, 2016. We performed crude and multivariable logistic regression, propensity score (PS) matching logistic regression, and inverse probability of treatment weighted (IPTW) regression to assess vaccine effectiveness (VE) against LBW, preterm birth, SGA, and stillbirth adjusting for measured confounders.

Results

Maternal vaccination status, antenatal history, and ≥1 birth outcome(s) were available for 4084/5333 (76.6%) pregnancies, 2109 (51.6%) vaccinated, and 1975 (48.4%) unvaccinated. The proportion LBW was lower in vaccinated (6.9%) vs. unvaccinated (12.5%) in multivariable [VE 0.27 (95% CI 0.07‐0.42)], PS [VE 0.30 (95% CI 0.09‐0.51)], and IPTW [VE 0.24 (95% CI 0.04‐0.45)]. Preterm birth was less frequent in vaccinated (8.6%) than unvaccinated (16.4%) in multivariable [VE 0.26 (0.09‐0.40)], PS [VE 0.25 (95% CI 0.09‐0.41)], and IPTW [VE 0.34 (95% CI 0.18‐0.51)]. The proportion SGA was lower in vaccinated (6.0%) than unvaccinated (8.8%) but not in adjusted models. There were few stillbirths in our study population, 30/4084 (0.7%).

Conclusions

Using multiple analytic approaches, we found that influenza vaccination was associated with lower prevalence of LBW (24‐30%) and preterm birth (25‐34%) in Cape Town during 2015‐2016.

Impact of Recommended Maternal Vaccination Programs on the Clinical Presentation of SARS-CoV-2 Infection: A Prospective Observational Study

The COVID-19 pandemic has raised questions about the possible cross immunity resulting from common vaccination programs and SARS-CoV-2 infection. Therefore, the Spanish Obstetric Emergency group performed a multicenter prospective study on the vaccination status of Influenza and Tdap (diphtheria, tetanus and pertussis vaccine boost administered in adulthood) in consecutive cases of SARS-CoV-2 infection in a pregnancy cohort, in order to assess its possible association with the clinical presentation and severity of symptoms of SARS-CoV-2 infection, as well as to determine the factors that may affect vaccination adherence. A total of 1150 SARS-CoV-2 positive pregnant women from 78 Spanish hospitals were analyzed: 183 had not received either vaccine, 23 had been vaccinated for Influenza only, 529 for Tdap only and 415 received both vaccines. No association was observed between the vaccination status and the clinical presentation of SARS-CoV-2 infection and/or the severity of symptoms. However, a lower adherence to the administration of both vaccines was observed in the Latin-American subgroup. Based on the results above, we reinforce the importance of maternal vaccination programs in the actual pandemic. Health education campaigns should be specially targeted to groups less likely to participate in these programs, as well as for a future SARS-CoV-2 vaccination campaign.

Influenza in Children

Influenza poses a significant disease burden on children worldwide, with high rates of hospitalization and substantial morbidity and mortality. Although the clinical presentation of influenza in children has similarities to that seen in adults, there are unique aspects to how children present with infection that are important to recognize. In addition, children play a significant role in viral transmission within communities. Growing evidence supports the idea that early influenza infection can uniquely establish lasting immunologic memory, making an understanding of how viral immunity develops in this population critical to better protect children from infection and to facilitate efforts to develop a more universally protective influenza vaccine.

Respiratory Syncytial Virus-Associated Hospitalization Rates among US Infants: A Systematic Review and Meta-Analysis

BACKGROUND

Although global reviews of infant RSV burden exist, none have summarized data from the United States or evaluated how RSV burden estimates are influenced by variations in study design.

METHODS

We performed a systematic literature review and meta-analysis of studies describing RSV-associated hospitalization rates among US infants and examined the impact of key study characteristics on these estimates.

RESULTS

We reviewed 3328 articles through August 14, 2020 and identified 25 studies with 31 unique estimates of RSV-associated hospitalization rates. Among US infants <1 year of age, annual rates ranged from 8.4 to 40.8 per 1000 with a pooled rate= 19.4 (95%CI: 17.9-20.9). Study type influenced RSV-associated hospitalization rates (P=.003), with active surveillance studies having pooled rates (11.0; 95%CI: 9.8-12.2) that were half that of studies based on administrative claims (21.4; 95%CI: 19.5-23.3) or modeling approaches (23.2; 95%CI: 20.2-26.2).

CONCLUSIONS

Applying our pooled rates to the 2020 US birth cohort suggests that 79,850 (95%CI: 73,680-86,020) RSV-associated infant hospitalizations occur each year. The full range of RSV-associated hospitalization rates identified in our review can better inform future evaluations of RSV prevention strategies. More research is needed to better understand differences in estimated RSV burden across study design.

Neuraminidase-specific antibody responses are generated in naive and vaccinated newborn nonhuman primates following virus infection

Individuals younger than 6 months of age are at significant risk from influenza virus infection; however, there is currently no vaccine approved for this age group. Influenza virus neuraminidase (NA) has emerged as a potential additional target for vaccine strategies. In this study, we sought to understand the ability of newborns to mount an antibody response to NA. Here we employed a nonhuman primate model, given the similarities to humans in immune system and development. We measured antibody to NA following infection with an H1N1 virus or following vaccination and challenge. Administration of an inactivated virus vaccine was not capable of eliciting detectable NA-specific antibody, even in the presence of adjuvants previously shown to increase total virus-specific IgG. However, both naive and vaccinated newborns generated a NA-specific antibody response following virus infection. Interestingly, the presence of the vaccine-induced response did not prevent generation of systemic antibody to NA following challenge, although the respiratory response was reduced in a significant portion of newborns. These findings are the first, to our knowledge, to evaluate the newborn response to the influenza NA protein as well as the impact of previous vaccination on generation of these antibodies following virus infection.

Assessing the epidemiology and seasonality of influenza among children under two hospitalized in Amman, Jordan, 2010-2013

Background

The disease burden of influenza‐associated hospitalizations among children in Jordan is not well established. We aimed to characterize hospitalizations attributed to influenza in a pediatric population.

Methods

We conducted a cross‐sectional study from our viral surveillance cohort in children under 2 years hospitalized with acute respiratory symptoms and/or fever from March 2010 to March 2013. We collected demographic and clinical characteristics, and calculated the frequency of children who met the severe acute respiratory illness (SARI) criteria. Nasal specimens were tested using real‐time reverse transcriptase polymerase chain reaction to detect influenza A, B, or C. Further subtyping for influenza A‐positive isolates was conducted.

Results

Of the 3168 children enrolled in our study, 119 (4%) were influenza‐positive. Influenza types and subtypes varied by season but were predominantly detected between December and February. Codetection of multiple respiratory pathogens was identified in 58% of children with the majority occurring among those <6 months. Bronchopneumonia and rule‐out sepsis were the most common admission diagnoses, with influenza A accounting for over 2/3 of children with a rule‐out sepsis admission status. One‐third of children under 6 months compared to 3/4 of children 6‐23 months met the SARI criteria.

Conclusions

Influenza was an important cause of acute respiratory illness in children under 2 years. Children <6 months had the highest burden of influenza‐associated hospitalizations and were less likely to meet the SARI global surveillance case definition. Additional surveillance is needed in the Middle East to determine the true influenza burden on a global scale.

Burden of influenza during the first year of life

Background

Every year, influenza viruses infect millions of children and cause an enormous burden of disease. Young children are at the highest risk for influenza‐attributable hospitalizations. Nevertheless, most young children are treated as outpatients, and limited data are available on the burden of influenza in these children.

Methods

We carried out a prospective cohort study and followed 431 infants born in June‐August 2017 for 10 months from September 1, 2017, to June 30, 2018. The parents filled out daily symptom diaries and were instructed to bring their child for clinical examination at our study clinic each time the child had fever or any signs or symptoms of respiratory tract infection. During each visit, we obtained nasopharyngeal swab specimens for determination of the viral etiology of the illness.

Results

A total of 55 episodes of laboratory‐confirmed influenza were diagnosed among the 408 actively participating children, which corresponds to an annual incidence rate of 135/1000 children (95% Cl, 102‐175). Excluding five children with double viral infection, acute otitis media developed as a complication of influenza in 23 (46%) children. One (2%) child with influenza was hospitalized because of febrile convulsion. The effectiveness of influenza vaccination was 48% (95% CI, −29%‐80%).

Conclusions

The burden of influenza during the first year of life is heavy in the outpatient setting where most infants with influenza are managed. Effective strategies for the prevention of influenza particularly in infants under 6 months of age are needed to diminish the burden of disease in this age group.

Cost-effectiveness analysis of influenza vaccination during pregnancy in Japan

BACKGROUND

Pregnant women and infants are known as high risk groups for influenza. WHO recommend pregnant women be vaccinated with inactivated influenza vaccine. In Japan, some municipalities started to give subsidy to encourage pregnant women to receive a shot on their own accord, which has made the introduction of seasonal antepartum maternal vaccination program (AMVP) into the routine vaccination list a current topic in health policy and has raised the need to evaluate the value for money of such possibility.

METHODS

We conducted a cost-effectiveness analysis to evaluate the efficiency of conducting AMVP in Japan. A decision tree model was adopted taking into consideration the duration of single-year vaccine effectiveness for infants and for mothers. The program targeted pregnant women aged 20-49 years old at or over 12 weeks gestation during October 1 through March 30. Estimated probabilities of treatments received due to influenza for pregnant/postpartum women or their infants varied by calendar time, vaccination status, and/or gestational age. Incremental cost-effectiveness ratio (ICER) compared with current no-AMVP from societal perspective was calculated. Transition probabilities, utility weights to estimate quality-adjusted life year (QALY), and disease treatment costs were either calculated or extracted from literature. Costs per vaccination was assumed at ¥3,529/US$32.1.

RESULTS

AMVP reduces disease treatment costs, while the reduction cannot offset the vaccination cost. Incremental QALYs were at 0.00009, among them 84.2% were from infants. ICER was ¥7,779,356/US$70,721 per QALY gained. One-way sensitivity analyses revealed that vaccine effectiveness for infant and costs per shot were the two main key variables affecting the ICER.

CONCLUSION

We found that vaccinating pregnant women with influenza vaccine to prevent unvaccinated infants and pregnant/postpartum women from influenza-associated disease in Japan can be cost-effective from societal perspective, under the WHO-suggested "cost-effective" criteria (1-3 times of GDP).

The Power of First Impressions: Can Influenza Imprinting during Infancy Inform Vaccine Design?

Influenza virus infection causes severe respiratory illness in people worldwide, disproportionately affecting infants. The immature respiratory tract coupled with the developing immune system, and lack of previous exposure to the virus is thought to synergistically play a role in the increased disease severity in younger age groups. No influenza vaccines are available for those under six months, although maternal influenza immunization is recommended. In children aged six months to two years, vaccine immunogenicity is dampened compared to older children and adults. Unlike older children and adults, the infant immune system has fewer antigen-presenting cells and soluble immune factors. Paradoxically, we know that a person's first infection with the influenza virus during infancy or childhood leads to the establishment of life-long immunity toward that particular virus strain. This is called influenza imprinting. We contend that by understanding the influenza imprinting event in the context of the infant immune system, we will be able to design more effective influenza vaccines for both infants and adults. Working through the lens of imprinting, using infant influenza animal models such as mice and ferrets which have proven useful for infant immunity studies, we will gain a better understanding of imprinting and its implications regarding vaccine design. This review examines literature regarding infant immune and respiratory development, current vaccine strategies, and highlights the importance of research into the imprinting event in infant animal models to develop more effective and protective vaccines for all including young children.

Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices - United States, 2020-21 Influenza Season

This report updates the 2019–20 recommendations of the Advisory Committee on Immunization Practices (ACIP) regarding the use of seasonal influenza vaccines in the United States (MMWR Recomm Rep 2019;68[No. RR-3]). Routine annual influenza vaccination is recommended for all persons aged ≥6 months who do not have contraindications. For each recipient, a licensed and age-appropriate vaccine should be used. Inactivated influenza vaccines (IIVs), recombinant influenza vaccine (RIV4), and live attenuated influenza vaccine (LAIV4) are expected to be available. Most influenza vaccines available for the 2020–21 season will be quadrivalent, with the exception of MF59-adjuvanted IIV, which is expected to be available in both quadrivalent and trivalent formulations.

Updates to the recommendations described in this report reflect discussions during public meetings of ACIP held on October 23, 2019; February 26, 2020; and June 24, 2020. Primary updates to this report include the following two items. First, the composition of 2020–21 U.S. influenza vaccines includes updates to the influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B/Victoria lineage components. Second, recent licensures of two new influenza vaccines, Fluzone High-Dose Quadrivalent and Fluad Quadrivalent, are discussed. Both new vaccines are licensed for persons aged ≥65 years. Additional changes include updated discussion of contraindications and precautions to influenza vaccination and the accompanying Table, updated discussion concerning use of LAIV4 in the setting of influenza antiviral medication use, and updated recommendations concerning vaccination of persons with egg allergy who receive either cell culture–based IIV4 (ccIIV4) or RIV4.

The 2020–21 influenza season will coincide with the continued or recurrent circulation of SARS-CoV-2 (the novel coronavirus associated with coronavirus disease 2019 [COVID-19]). Influenza vaccination of persons aged ≥6 months to reduce prevalence of illness caused by influenza will reduce symptoms that might be confused with those of COVID-19. Prevention of and reduction in the severity of influenza illness and reduction of outpatient illnesses, hospitalizations, and intensive care unit admissions through influenza vaccination also could alleviate stress on the U.S. health care system. Guidance for vaccine planning during the pandemic is available at https://www.cdc.gov/vaccines/pandemic-guidance/index.html.

This report focuses on recommendations for the use of vaccines for the prevention and control of seasonal influenza during the 2020–21 season in the United States. A brief summary of the recommendations and a link to the most recent Background Document containing additional information are available at https://www.cdc.gov/vaccines/hcp/acip-recs/vacc-specific/flu.html. These recommendations apply to U.S.-licensed influenza vaccines used within Food and Drug Administration (FDA)–licensed indications. Updates and other information are available from CDC’s influenza website (https://www.cdc.gov/flu). Vaccination and health care providers should check this site periodically for additional information.

Implementation of the United Kingdom's childhood influenza national vaccination programme: A review of clinical impact and lessons learned over six influenza seasons

In 2012, the Joint Committee on Vaccination and Immunisation recommended that the United Kingdom's (UK) National Vaccination Programme (NVP) for influenza was extended to include healthy children and adolescents aged 2 to <17 years. Previously, the UK's NVP focused on seasonal vaccination of the elderly and people (including children) with underlying health conditions that put them at high risk of hospitalisation if they contracted influenza. The extension of the UK's programme began in the 2013/14 influenza season through the vaccination of children aged 2-3 years in primary care across England and the devolved administrations of Scotland, Wales, and Northern Ireland. School-aged children were generally vaccinated in a school setting, with several implementation pilots in England and Scotland. Due to the scale of the programme, it has been phased in over several years and expanded to include broader childhood age groups. This article reviews the experiences from the implementation of the UK's childhood influenza NVP over the first six influenza seasons (between 2013/14 and 2018/19) from the perspectives of England, Scotland, Wales, and Northern Ireland. The processes used to deliver the vaccination programme in general practice and the school-based setting are described in terms of governance, contracting, workforce management, communication, administrative tasks, vaccination sessions, vaccine supply and distribution, and surveillance. In addition, the available evidence regarding the clinical impact of the UK's childhood influenza NVP over the first six influenza seasons is reviewed. We also share lessons learned from the programme and recommendations to provide guidance to other countries looking to implement childhood influenza vaccination programmes.

Quantifying the annual incidence and underestimation of seasonal influenza: A modelling approach

BACKGROUND

Seasonal influenza poses a significant public health and economic burden, associated with the outcome of infection and resulting complications. The true burden of the disease is difficult to capture due to the wide range of presentation, from asymptomatic cases to non-respiratory complications such as cardiovascular events, and its seasonal variability. An understanding of the magnitude of the true annual incidence of influenza is important to support prevention and control policy development and to evaluate the impact of preventative measures such as vaccination.

METHODS

We use a dynamic disease transmission model, laboratory-confirmed influenza surveillance data, and randomized-controlled trial (RCT) data to quantify the underestimation factor, expansion factor, and symptomatic influenza illnesses in the US and Canada during the 2011-2012 and 2012-2013 influenza seasons.

RESULTS

Based on 2 case definitions, we estimate between 0.42-3.2% and 0.33-1.2% of symptomatic influenza illnesses were laboratory-confirmed in Canada during the 2011-2012 and 2012-2013 seasons, respectively. In the US, we estimate between 0.08-0.61% and 0.07-0.33% of symptomatic influenza illnesses were laboratory-confirmed in the 2011-2012 and 2012-2013 seasons, respectively. We estimated the symptomatic influenza illnesses in Canada to be 0.32-2.4 million in 2011-2012 and 1.8-8.2 million in 2012-2013. In the US, we estimate the number of symptomatic influenza illnesses to be 4.4-34 million in 2011-2012 and 23-102 million in 2012-2013.

CONCLUSIONS

We illustrate that monitoring a representative group within a population may aid in effectively modelling the transmission of infectious diseases such as influenza. In particular, the utilization of RCTs in models may enhance the accuracy of epidemiological parameter estimation.

Characteristics and outcomes of critically ill patients with influenza A (H1N1) in the Western Balkans during the 2019 post-pandemic season

Background

This study looked at the characteristics and outcomes of critically ill patients with confirmed influenza A (H1N1) pdm09 infection in the Western Balkans in the post-pandemic period.

Materials and Methods

This retrospective observational study of medical records and associated data collected during the post-pandemic period included all mechanically ventilated adult patients of two university-affiliated hospitals of the Western Balkans between 1 January and 31 March 2019 who had influenza A (H1N1) pdm09 infection confirmed by real-time reverse transcriptase-polymerase chain reaction from nasopharyngeal swab specimens and respiratory secretions.

Results

The study included 89 patients, 49 males (55.1%), aged 56.09 ± 12.64 years. The median time from shift from hospital time to intensive care unit was 1 day (range: 1-2). In the post-pandemic period, cases observed in this study were found to have the following comorbidities: cardiovascular diseases in 44 (49.4%) patients and diabetes in 21 (23.6%) patients. Thirty-one patients (34.8%) in this study were obese. All 89 patients (100%) experienced some degree of acute respiratory distress syndrome, and 39 (44%) had multiorgan failure. Eighty-three patients (93%) were intubated and mechanically ventilated, 6 (7%) received non-invasive mechanical ventilation, 12 (13%) were treated with vvECMO and 36 (40%) received renal replacement therapy. Vasoactive support was needed by 56 (63%) patients. The median duration of mechanical ventilation was 9 (6-15.5) days. The hospital mortality rate was 44%.

Conclusion

Critically ill patients with confirmed influenza A (H1N1) pdm09 infection in the post-pandemic season were older, required vasoactive drugs more often, and there was a trend of higher survival compared to H1N1 infection patients in the previous pandemic seasons.

Parental Hesitancy About Routine Childhood and Influenza Vaccinations: A National Survey

BACKGROUND AND OBJECTIVES

The World Health Organization has designated vaccine hesitancy as 1 of the 10 leading threats to global health, yet there is limited current national data on prevalence of hesitancy among US parents. Among a nationally representative sample of US parents, we aimed to (1) assess and compare prevalence of hesitancy and factors driving hesitancy for routine childhood and influenza vaccination and (2) examine associations between sociodemographic characteristics and hesitancy for routine childhood or influenza vaccination.

METHODS

In February 2019, we surveyed families with children using the largest online panel generating representative US samples. After weighting, we assessed hesitancy using a modified 5-point Vaccine Hesitancy Scale and labeled parents as hesitant if they scored >3.

RESULTS

A total of 2176 of 4445 parents sampled completed the survey (response rate 49%). Hesitancy prevalence was 6.1% for routine childhood and 25.8% for influenza vaccines; 12% strongly and 27% somewhat agreed they had concerns about serious side effects of both routine childhood and influenza vaccines. A total of 70% strongly agreed that routine childhood vaccines are effective versus 26% for influenza vaccine (P < .001). In multivariable models, an educational level lower than a bachelor's degree and household income <400% of the federal poverty level predicted hesitancy about both routine childhood and influenza vaccines.

CONCLUSIONS

Almost 1 in 15 US parents are hesitant about routine childhood vaccines, whereas >1 in 4 are hesitant about influenza vaccine. Furthermore, 1 in 8 parents are concerned about vaccine safety for both routine childhood and influenza vaccines, and only 1 in 4 believe influenza vaccine is effective. Vaccine hesitancy, particularly for influenza vaccine, is prevalent in the United States.

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

Immunization during pregnancy has been recommended in an increasing number of countries. The aim of this strategy is to protect pregnant women and infants from severe infectious disease, morbidity and mortality and is currently limited to tetanus, inactivated influenza, and pertussis-containing vaccines. There have been recent advancements in the development of vaccines designed primarily for use in pregnant women (respiratory syncytial virus and group B Streptococcus vaccines). Although there is increasing evidence to support vaccination in pregnancy, important gaps in knowledge still exist and need to be addressed by future studies. This collaborative consensus paper provides a review of the current literature on immunization during pregnancy and highlights the gaps in knowledge and a consensus of priorities for future research initiatives, in order to optimize protection for both the mother and the infant.

Comparative Severity of Influenza A and B Infections in Hospitalized Children

BACKGROUND

Influenza A viruses are conventionally thought to cause more severe illnesses than B viruses, but few studies with long observation periods have compared the clinical severity of A and B infections in hospitalized children.

METHODS

We analyzed the clinical presentation, outcomes and management of all children <16 years of age admitted to Turku University Hospital, Finland, with virologically confirmed influenza A or B infection during the 14-year period of 1 July 2004 to 30 June 2018. All comparisons between influenza A and B were performed both within predefined age groups (0-2, 3-9 and 10-15 years) and in all age groups combined.

RESULTS

Among 391 children hospitalized with influenza A or B infection, influenza A was diagnosed in 279 (71.4%) and influenza B in 112 (28.6%) children. Overall, there were no significant differences in any clinical features or outcomes, management, treatment at intensive care unit or length of stay between children with influenza A and B, whether analyzed by age group or among all children. As indicators of the most severe clinical presentations, blood cultures were obtained from 101 (36.2%) children with influenza A and 39 (34.8%) with influenza B (P = 0.80), and lumbar puncture was performed to 16 (5.7%) children with influenza A and 11 (9.8%) children with influenza B (P = 0.15).

CONCLUSIONS

The clinical severity of influenza A and B infections is similar in children. For optimal protection against severe influenza illnesses, the use of quadrivalent vaccines containing both lineages of B viruses seems warranted in children.

Sinensetin suppresses influenza a virus-triggered inflammation through inhibition of NF-κB and MAPKs signalings

Background

Human respiratory system infected with influenza A virus (IAV) elicited a robust pro-inflammatory response that resulted in severe illness and even death. Currently, limited immunomodulator is available to counteract IAV-associated pneumonia in the clinic. Sinensetin, a polymethoxylated flavone with five methoxy groups, has been found to possess anti-agiogenesis, anti-inflammatory and anti-diabetic activities. However, the effects of sinensetin on IAV-triggered pro-inflammatory response remain unclear. In the present study, the anti-inflammatory effects and corresponding possible mechanism of sinensetin in IAV-infected A549 cells were subjected to investigations.

Methods

The cytotoxic effects of sinensetin towards A549 cells was detected by MTT and LDH assays. The antiviral activity of sinensetin against influenza A virus was assayed in A549 cells with an engineered replication-competent influenza A virus carrying Gaussia luciferase reporter gene infection. The effect of sinensetin on influenza A virus-triggered inflammatory reaction was determined by qRT-PCR, Luminex assays, ELISA and Western blot.

Results

Our results showed that sinensetin did not exhibit antiviral activity against A/PR/8/34 (H1N1). Meanwhile, sinensetin treatment significantly decreased IAV-induced expression of pro-inflammatory mediators at mRNA and protein levels, including IL-6, TNF-α, IP-10, IL-8 and MCP-1. Additionally, levels of cyclooxygenase (COX)-2 and the downstream product prostaglandin E₂ (PGE₂) up-regulated by IAV infection were dramatically suppressed by sinensetin. The mechanistic investigation revealed that sinensetin treatment suppressed the NF-κB transcriptional activity using the NF-κB reporter stable HEK293 cell line stimulated with TNF-α (20 ng/mL) or influenza H1N1 virus. Furthermore, sinensetin abrogated influenza H1N1 virus-induced activation of NF-κB, ERK1/2 MAPK and p38 MAPK signalings.

Conclusion

Collectively, our results indicated that sinensetin has potential capacity to attenuate IAV-triggered pro-inflammatory response via inactivation of NF-κB, ERK1/2 MAPK and p38 MAPK signalings, which implied that sinensetin may be a promising candidate drug for influenza H1N1 virus infection therapeutics.

Impact of media reports regarding influenza vaccine on obstetricians' vaccination practices

BACKGROUND

In 2017, three media stories regarding influenza vaccine may have impacted obstetricians' (OB) influenza vaccination practices: reports of reduced influenza vaccine effectiveness, a severe influenza season, and a possible increased risk of miscarriage among pregnant women receiving 2009 H1N1 vaccine in the 1st trimester who had received H1N1 vaccine the previous season (later disproven).

OBJECTIVE

Describe OB's: (1) awareness of; (2) attitudes and experiences related to; and (3) reported alterations in practice as a result of these reports.

METHODS

A survey among a nationally representative sample of OBs April to June 2018.

RESULTS

Response rate was 65% (302/468). 88% of OBs were "very aware" of the severe season, 74% of lower effectiveness, and 25% of the miscarriage study (47% "completely unaware" of miscarriage study). Among those aware, 58%, 57%, and 16% reported ≥10% of pregnant patients initiated discussions about the severe season, lower effectiveness, and miscarriage study, respectively. Most (83%) agreed reports about increased severity increased their enthusiasm for recommending influenza vaccine; fewer agreed reports about the miscarriage study (18%) and lower vaccine effectiveness (12%) decreased their enthusiasm for recommending influenza vaccine. Providers were more likely to initiate discussion with patients about increased severity of the season than the other reports. However, 35% agreed the miscarriage study reports increased their concerns about influenza vaccine safety; 18% (n = 48) reported changing the way they recommended influenza vaccine. Of those, 17 (6% of all respondents) reported not recommending influenza vaccine to women during the 1st trimester and 26 (10% of all respondents) recommended it but were willing to delay until the 2nd trimester.

CONCLUSIONS

During a season in which media stories could have influenced OB influenza vaccination behaviors in different directions, reports underscoring importance of influenza vaccine may have had more impact on OBs' recommendations than reports questioning vaccine safety or effectiveness.

Influenza vaccine effectiveness in children: a retrospective study on eight post-pandemic seasons with trivalent inactivated vaccine

Background and aim of the work:

The global burden of disease attributable to seasonal influenza virus in children is difficult to quantify. Children with chronic medical conditions and healthy children may experience severe or fatal complications. Aim of the study was to estimate the influenza vaccine effectiveness (VE) in a cohort of outpatient children.

Methods:

From 2010 to 2018, a Pediatrician of Parma from the InfluNet network of Emilia-Romagna Region, performed nasal/throat swabs on every child with Influenza-like illness at least 14 days from the vaccination with trivalent vaccine. VE estimates against influenza season, virus type and subtype and age group were evaluated using a test-negative design.

Results:

2,480 swabs were performed. The 57.6% of the analyzed swabs were positive for influenza viruses. Type A (57%) and type B viruses (43%) co-circulated. The 37.1% of type A viruses belonged to subtype A(H3N2), 19.4% to subtype A(H1N1)pdm09. The subtype A(H3N2) was prevalent among children up to 23 months (42.4%) while the type B in the 2-4 (40.7%) and 5-16 year old age groups (49.4%). Overall, 19.9% of the children were vaccinated. The highest prevalence of vaccinated subjects was found in children aged 5-16 (30.5%). The VE against subtype A(H1N1)pdm09 was 63% (95%CI 42.6-76.0), against type B 27.5% (95%CI 7.9-42.9) and against subtype A(H3N2) -14.3% (95%CI - 46.0-10.7).

Conclusions:

Our findings represent a useful contribution to the ongoing debate about the appropriateness of including influenza vaccination for healthy children, 6 months and older, in the updating National Vaccine Prevention Plan (PNPV).

Viral etiology of life-threatening pediatric pneumonia: A matched case-control study

Background

Pediatric pneumonia remains a significant health challenge, while the viral risk factors for adverse outcomes in pediatric pneumonia are not yet fully clear.

Methods

A matched case‐control study of pediatric patients with pneumonia was carried out in Beijing, China, between 2007 and 2015. The study enrolled 334 intensive care unit patients who developed life‐threatening diseases and 522 controls matched to the sex, age, ethnicity, admission dates, and residing district of the cases suffered from pneumonia. Nasopharyngeal aspirates were taken from all participants and tested by PCR for 18 common respiratory viruses.

Results

At least, one virus was detected in 257 (77%) of the cases and 409 (78%) of the controls. We observed no difference in the prevalence of 17 respiratory viruses between cases and controls but found a higher frequency of influenza A virus (IFV‐A) in the cases than in the controls (7% vs 4%, P = .036). After adjusting for comorbid conditions and a history of reactive airway diseases, IFV‐A was associated with an increase in life‐threatening pneumonia (adjusted odds ratio = 2.55, 95% CI = 1.24‐5.24). Young age and congenital heart disease (aOR = 10.16‐10.27, P < .001) were also independent risk factors.

Conclusions

The prevention of IFV infection is critical in decreasing the risk of life‐threatening pneumonia in children.

Nasopharyngeal Pneumococcal Density during Asymptomatic Respiratory Virus Infection and Risk for Subsequent Acute Respiratory Illness

Increased nasopharyngeal pneumococcal (Streptococcus pneumoniae) colonization density has been associated with invasive pneumococcal disease, but factors that increase pneumococcal density are poorly understood. We evaluated pneumococcal densities in nasopharyngeal samples from asymptomatic young children from Peru and their association with subsequent acute respiratory illness (ARI). Total pneumococcal densities (encompassing all present serotypes) during asymptomatic periods were significantly higher when a respiratory virus was detected versus when no virus was detected (p<0.001). In adjusted analyses, increased pneumococcal density was significantly associated with the risk for a subsequent ARI (p<0.001), whereas asymptomatic viral detection alone was associated with lower risk for subsequent ARI. These findings suggest that interactions between viruses and pneumococci in the nasopharynx during asymptomatic periods might have a role in onset of subsequent ARI. The mechanisms for these interactions, along with other potentially associated host and environmental factors, and their role in ARI pathogenesis and pneumococcal transmission require further elucidation.

Centralized Reminder/Recall to Increase Influenza Vaccination Rates: A Two-State Pragmatic Randomized Trial

OBJECTIVE

Centralized reminder/recall (C-R/R) by health departments using immunization information systems is more effective and cost effective than practice-based approaches for increasing childhood vaccines but has not been studied for influenza vaccination. We assessed effectiveness and cost of C-R/R for increasing childhood influenza vaccination compared with usual care.

METHODS

Within Colorado (CO) and New York (NY), random samples of primary care practices (pediatric, family medicine, and health center) were selected proportionate to where children are served-65 practices (N = 54,353 children) in CO; 101 practices (N = 65,777) in NY. We conducted 4-arm RCTs per state (1, 2, or 3 autodial reminders vs usual care), with randomization at the patient level within practices from 10/2016 to 1/2017.

RESULTS

In CO, the maximum absolute difference in receipt of ≥1 influenza vaccine was 1.7% between the 2 R/R group and control (adjusted risk ratio [ARR] of 1.06 [1.01, 1.10]); other R/R arms did not differ significantly. In NY, ARRs for the study arms versus control varied from 1.05 (1.01, 1.10) for 3 R/R to 1.06 (1.01, 1.11) for 1-2 R/R groups and maximum absolute increase in vaccination was 0.6%. In time-to-event analyses, study arm was a significant predictor of vaccination in CO (P = .001) but not in NY. Costs/child randomized to one message were $.17 in CO and $.23 in NY.

CONCLUSIONS

C-R/R for influenza vaccine using autodial had low-level effects on increasing influenza rates in 2 states. Given the feasibility and low cost of C-R/R in previous trials, its utility for influenza should be re-examined using different modalities.

Trend of influenza vaccine Facebook posts in last 4 years: a content analysis

BACKGROUND

Decreasing immunization rates may be partly due to antivaccine campaigns and other sources of misinformation available on social media, particularly on Facebook. Given the potential impact of this medium for communicating vaccine-related information, it is important to analyze the trend of information available on Facebook.

METHODS

We searched Facebook on August 15, 2018 to obtain posts containing relevant health information on influenza vaccine in years 2015-2018. We collected information regarding nature of the post (eg, pro-, antivaccine, and informational), number of shares and likes received, and ease of reading for each post. We evaluated these characteristics by year and type of post in our exploratory analyses.

RESULTS

The proportion of pro-vaccine posts has increased compared to antivaccine and informational posts since 2016. There was no correlation between ease of reading and popularity of posts. Although the language of antivaccine posts was complex, they were shared and liked more than pro-vaccine posts. The pro-vaccine personal post by a nurse was the most popular in our study (shared over 46,000 times) in 2018.

CONCLUSIONS

Though the number of pro-vaccine posts increased, antivaccine posts remained more popular. The government agency may use an emotive personal family-oriented message to promote vaccination.

Nontraditional Uses of Live Attenuated Influenza Vaccine: School-Located Influenza Vaccination

Immunization against influenza continues to be the best method of preventing influenza infection in children, and additionally, indirectly helping to lower disease in adults, given the role of children as "spreaders" of influenza to the community at large. An increasing evidence base exists for the use of school-located influenza vaccination (SLIV) programs to increase the influenza vaccination rates among children. Live, attenuated influenza vaccine (LAIV) has unique characteristics that make it useful for SLIV programs, including ease of immunization without needles, faster delivery, and in many (but not all) years, good vaccine effectiveness. Reviewed herein are results of selected published trials as well as guidance on planning a successful SLIV program.

Differential diagnosis of illness in patients under investigation for the novel coronavirus (SARS-CoV-2), Italy, February 2020

A novel coronavirus (SARS-CoV-2) has been identified as the causative pathogen of an ongoing outbreak of respiratory disease, now named COVID-19. Most cases and sustained transmission occurred in China, but travel-associated cases have been reported in other countries, including Europe and Italy. Since the symptoms are similar to other respiratory infections, differential diagnosis in travellers arriving from countries with wide-spread COVID-19 must include other more common infections such as influenza and other respiratory tract diseases.

Influenza-infected newborn and adult monkeys exhibit a strong primary antibody response to hemagglutinin stem

The specificity of antibodies (Abs) generated against influenza A virus (IAV) infection can significantly alter protection and viral clearance. At present, the impact of age upon this process is relatively unexplored. Here, we evaluated the Ab response in newborn and adult African green monkeys following infection with IAV using a strain that enables us to determine the immunodominance (ID) hierarchy of the Ab response to hemagglutinin (HA), the principal target of protective Abs. This revealed altered ID patterns in the early IgM anti-HA response in newborns versus adults that converged over time. While the IgG ID profiles for HA in newborn and adult monkeys were similar, this was not the case for IgA. Importantly, HA stem-specific Abs were generated robustly and similarly in newborns and adults in terms of quality and quantity. Together, these results demonstrate that newborns and adults can differ in the Ab ID pattern established following infection and that the ID pattern can vary across isotypes. In addition, newborns have the ability to generate potent HA stem-specific Ab responses. Our findings further the understanding of the newborn response to IAV antigens and inform the development of improved vaccines for this at-risk population.

Tetanus, Diphtheria, and Acellular Pertussis and Influenza Vaccinations among Women With a Live Birth, Internet Panel Survey, 2017-2018

Objectives

Pregnant women are at increased risk of complications from influenza, and infants are at increased risk of pertussis. Maternal influenza and Tdap (tetanus, diphtheria, and acellular pertussis) vaccination can reduce risk of these infections and related complications. Our objective was to estimate vaccination coverage with influenza and Tdap vaccines during pregnancy among women with a recent live birth.

Methods

An opt-in Internet panel survey was conducted from March 28 to April 10, 2018 among pregnant and recently pregnant women. Respondents with a live birth from August 1, 2017 through the date in which the participant completed the survey were included in the analysis. Receipt of influenza vaccination since July 1, 2017 and Tdap vaccination during pregnancy were assessed by sociodemographic characteristics, receipt of a health care provider (HCP) recommendation and/or offer of vaccination, and vaccination-related knowledge, attitudes, and beliefs.

Results

Less than a third (30.3%) of women with a live birth were unvaccinated during their pregnancy with both Tdap and influenza vaccines. Almost a third (32.8%) of the women reported being vaccinated with both vaccines. The majority (73.0%) of women reported receiving an HCP recommendation for both vaccines, and 54.2% of women were offered both vaccines by an HCP. Reasons for nonvaccination included negative attitudes toward influenza vaccine and lack of awareness about Tdap vaccination during pregnancy.

Conclusions

Maternal Tdap and influenza vaccinations can prevent morbidity and mortality among infants and their mothers, yet many pregnant women are unvaccinated with either Tdap or influenza vaccines. Clinic-based education, along with interventions, such as standing orders and provider reminders, are strategies to increase maternal vaccination.

A severe influenza season in Austria and its impact on the paediatric population: mortality and hospital admission rates, november 2017 - march 2018

BACKGROUND

In Austria paediatric influenza-associated hospitalisations and deaths have never been systematically monitored. We examined the influenza season 2017/18 in terms of hospitalisation and mortality in the Austrian paediatric population and put the results into perspective of the available data from the last 15 years.

METHODS

Cases of influenza-associated hospitalisations and deaths for season 2017/18 in children below 18 years were retrospectively collected from 12 and 33 Austrian hospitals, respectively. Hospitalisation and mortality rates for the whole Austrian paediatric population were estimated, adjusting for the population in each catchment area. Two Austrian databases were queried for hospitalisations and deaths associated with influenza during 2002-2016. Rough estimate of the vaccination coverage was calculated from a survey on 100 inpatients.

RESULTS

Influenza-related paediatric hospitalisation rate in season 2017/18 was estimated as 128 (CI: 122-135) per 100,000 children, much higher than the national average of 40 per 100,000 over the years 2002-2016. There were nine reported influenza-associated deaths among children, resulting in mortality rate of 0.67 (CI: 0.32-1.21) per 100,000 children.

CONCLUSIONS

Reported influenza-associated hospitalisations and fatalities demonstrate a high burden of influenza in the Austrian paediatric population corresponding with very low vaccination coverage.

An investigation into respiratory tract viruses in children with acute lower respiratory tract infection or wheezing

BACKGROUND

This study aimed to determine the frequencies of respiratory tract viruses in patient (acute lower respiratory tract infection [LRTI] or wheezing) and control (history of asthma without symptoms) groups.

METHODS

Using multiplex-polymerase chain reaction (PCR), respiratory tract viruses were investigated in the respiratory tract specimens from patient and control groups followed in the Pediatric Clinic.

RESULTS

The viruses detected in the patient and control groups (P=0.013) were as follows, respectively: rhinoviruses A, B, C (25.6% and 36.7%), influenza virus A (21.1% and 0.0%), parainfluenza virus type 1 (7.8% and 1.7%), parainfluenza virus type 4 (5.6% and 0.0%), adenoviruses A, B, C, D, E (4.4% and 1.7%), parainfluenza virus type 3 (4.4% and 1.7%), coronaviruses 229E and NL63 (4.4% and 1.7%), coronavirus OC43 (3.3% and 0.0%), respiratory syncytial virus A (3.3% and 0.0%), parainfluenza virus type 2 (2.2% and 0.0%), influenza virus B (2.2% and 0.0%), and respiratory syncytial virus B (1.1% and 1.7%). No bocavirus, metapneumovirus or enterovirus was found in any specimen. Statistically significant differences in the detection of influenza virus A (P=0.000), the total detection of parainfluenza viruses (P=0.008) and coinfection (P=0.004) were observed between the patient and control groups.

CONCLUSIONS

The advantage of our study compared with other studies is the inclusion of not only wheezing patients but also children with asthma without symptom. The higher detection of rhinoviruses both in patient and control groups give rise to thought that these viruses may be responsible for asthma exacerbations and may be related with long duration of virus shedding.

A model of influenza infection and vaccination in children aged under 5 years in Beijing, China

BACKGROUND

Children aged under 5 years are particularly vulnerable to influenza infection. In this study, we aim to estimate the number and incidence of influenza among young children and estimate the impact of childhood vaccination in different scenarios from 2013/14 to 2016/17 seasons.

METHODS

The number and incidence rate of influenza infections among children aged under 5 years in Beijing was estimated by scaling up observed surveillance data. Then, we used a susceptible-exposed-infected-recovery (SEIR) model to reproduce the weekly number of influenza infections estimated in Beijing during the study seasons, and to estimate the number and proportion of influenza-attributed medically attended acute respiratory infections (I-MAARI) averted by vaccination in each season. Finally, we evaluated the impact of alternative childhood vaccination programs with different coverage and speed of vaccine distribution.

RESULTS

The estimated average annual incidence of influenza in children aged under 5 years was 33.9% (95% confidence interval (CI): 27.5%, 47.2%) during the study period. With the actual coverage during the included seasons at around 2.9%, an average of 3.9% (95%CI: 3.5%, 4.4%) I-MAARI was reduced compared to a no-vaccination scenario. Reaching 20%, 40%, 50%, 60%, 80% and 100% vaccine coverage would lead to an overall I-MAARI reduction of 25.3%, 42.7%, 51.9%, 57.0%, 65.3% and 71.2%. At 20% coverage scenario, an average of 28.8% I-MAARI will be prevented if intensive vaccination implemented in 2 months since the vaccine released.

CONCLUSION

In Beijing, the introduction of a program for vaccinating young children, even at relatively low vaccine coverage rates, would considerably reduce I-MAARI, particularly if the vaccines can be quickly delivered.

Serious outcomes of medically attended, laboratory-confirmed influenza illness among school-aged children with and without asthma, 2007-2018

Background

Asthma was associated with influenza hospitalizations in children during the 2009 pandemic, but it is unclear if asthma is associated with serious illness during seasonal epidemics. Little is known regarding the effect of vaccination on influenza severity in children with asthma.

Methods

Children aged 5‐17 years in a community cohort presenting with acute respiratory illness were prospectively enrolled and tested for influenza from 2007‐08 through 2017‐18 (excluding the 2009‐10 pandemic season). Data from the electronic health record were extracted to determine asthma status and serious outcomes associated with influenza infection. A serious outcome was defined as hospitalization, emergency department visit, and/or pneumonia diagnosis within 30 days of symptom onset. Multivariable logistic regression models were used to assess asthma status and effect of vaccination on odds of a serious outcome.

Results

One thousand seven hundred and sixty four medically‐attended influenza infections among school‐aged children were included. Asthma was confirmed in 287 (16%) children. A serious influenza‐associated outcome occurred in 104 (6%) children. The odds of a serious outcome did not differ between those with confirmed asthma and those without asthma [adjusted odds ratio (aOR): 1.35, 95% confidence interval (CI): (0.77‐2.35), P = .3]. The effect of vaccination on serious outcomes was not modified by asthma status [aOR for children without asthma: 0.55 (95% CI: 0.28‐1.07), children with asthma: 1.39 (95% CI: 0.53‐3.69); interaction P‐value = .12].

Conclusions

Asthma was not a risk factor for serious illness among children with influenza. Additional studies are needed to better understand the role of influenza vaccination in preventing serious outcomes among children with asthma.