Epidemiology of 2009 pandemic influenza A (H1N1) in the United States

How does date-rounding affect phylodynamic inference for public health?

Phylodynamic analyses infer epidemiological parameters from pathogen genome sequences for enhanced genomic surveillance in public health. Pathogen genome sequences and their associated sampling dates are the essential data in every analysis. However, sampling dates are usually associated with hospitalisation or testing and can sometimes be used to identify individual patients, posing a threat to patient confidentiality. To lower this risk, sampling dates are often given with reduced date-resolution to the month or year, which can potentially bias inference. Here, we introduce a practical guideline on when date-rounding biases the inference of epidemiologically important parameters across a diverse range of empirical and simulated datasets. We show that the direction of bias varies for different parameters, datasets, and tree priors, while compounding with lower date-resolution and higher substitution rates. We also find that bias decreases for datasets with longer sampling intervals, implying that our guideline is most applicable to emerging datasets. We conclude by discussing future solutions that prioritise patient confidentiality and propose a method for safer sharing of sampling dates that translates them them uniformly by a random number.

The peculiar characteristics and advancement in diagnostic methodologies of influenza A virus

Influenza A virus (IAV) is a significant public health concern, causing seasonal outbreaks and occasional pandemics. These outbreaks result from changes in the virus's surface proteins which include hemagglutinin and neuraminidase. Influenza A virus has a vast reservoir, including wild birds, pigs, horses, domestic and marine animals. It has over 130 subtypes based on differences in hemagglutinin and neuraminidase protein. IAV affects all age groups but impacts young children more especially during the colder season. Despite the development of vaccines and antiviral drugs, IAV is still a major cause of respiratory illnesses and deaths. Surveillance of IAV is crucial to detect new strains and assess vaccine effectiveness. Detection of IAV relies on methods like hemagglutination assay, PCR, cell culturing, and immunochromatography-based tests. Precise and early detection of IAV strain is crucial for quick treatment using antiviral drugs and unraveling epidemiological patterns to curb epidemics and pandemics on time. Advancements in diagnostic methodologies have enabled us to detect the IAV at early stages by overcoming the limitations of previously used diagnostic tests, further preparing us to combat future epidemics more effectively. This review article discusses the traditional and advanced diagnosis methods for detecting IAV.

Changing epidemic patterns of infectious diseases during and after COVID-19 pandemic in Taiwan

Mitigation measures aimed at curbing the transmission of the severe acute respiratory syndrome coronavirus 2 effectively suppressed the occurrence of many respiratory infections other than coronavirus disease 2019. Several infections experienced a resurgence following the relaxation of non-pharmaceutical interventions, surpassing pre-pandemic levels in Taiwan. This phenomenon, known as immune debt, primarily affected respiratory infections in young children, including respiratory syncytial virus (RSV) infection. Infections transmitted by means other than droplets or contact did not exhibit significant changes in their epidemic patterns, such as varicella and Japanese encephalitis. Alterations in seasonality were noted for RSV infection and influenza, and these changes are also linked to immune debt. The recent emergence of severe pediatric pneumonia in northern China may be associated with immune debt and the rise of macrolide-resistant Mycoplasma pneumoniae associated with severe illness.

If Long-Term Suppression is not Possible, how do we Minimize Mortality for Infectious Disease Outbreaks?

OBJECTIVE

For any emerging pathogen, the preferred approach is to drive it to extinction with non-pharmaceutical interventions (NPI) or suppress its spread until effective drugs or vaccines are available. However, this might not always be possible. If containment is infeasible, the best people can hope for is pathogen transmission until population level immunity is achieved, with as little morbidity and mortality as possible.

METHODS

A simple computational model was used to explore how people should choose NPI in a non-containment scenario to minimize mortality if mortality risk differs by age.

RESULTS

Results show that strong NPI might be worse overall if they cannot be sustained compared to weaker NPI of the same duration. It was also shown that targeting NPI at different age groups can lead to similar reductions in the total number of infected, but can have strong differences regarding the reduction in mortality.

CONCLUSIONS

Strong NPI that can be sustained until drugs or vaccines become available are always preferred for preventing infection and mortality. However, if people encounter a worst-case scenario where interventions cannot be sustained, allowing some infections to occur in lower-risk groups might lead to an overall greater reduction in mortality than trying to protect everyone equally.

Multimodeling approach to evaluating the efficacy of layering pharmaceutical and nonpharmaceutical interventions for influenza pandemics

When an influenza pandemic emerges, temporary school closures and antiviral treatment may slow virus spread, reduce the overall disease burden, and provide time for vaccine development, distribution, and administration while keeping a larger portion of the general population infection free. The impact of such measures will depend on the transmissibility and severity of the virus and the timing and extent of their implementation. To provide robust assessments of layered pandemic intervention strategies, the Centers for Disease Control and Prevention (CDC) funded a network of academic groups to build a framework for the development and comparison of multiple pandemic influenza models. Research teams from Columbia University, Imperial College London/Princeton University, Northeastern University, the University of Texas at Austin/Yale University, and the University of Virginia independently modeled three prescribed sets of pandemic influenza scenarios developed collaboratively by the CDC and network members. Results provided by the groups were aggregated into a mean-based ensemble. The ensemble and most component models agreed on the ranking of the most and least effective intervention strategies by impact but not on the magnitude of those impacts. In the scenarios evaluated, vaccination alone, due to the time needed for development, approval, and deployment, would not be expected to substantially reduce the numbers of illnesses, hospitalizations, and deaths that would occur. Only strategies that included early implementation of school closure were found to substantially mitigate early spread and allow time for vaccines to be developed and administered, especially under a highly transmissible pandemic scenario.

Missing science: A scoping study of COVID-19 epidemiological data in the United States

Systematic approaches to epidemiologic data collection are critical for informing pandemic responses, providing information for the targeting and timing of mitigations, for judging the efficacy and efficiency of alternative response strategies, and for conducting real-world impact assessments. Here, we report on a scoping study to assess the completeness of epidemiological data available for COVID-19 pandemic management in the United States, enumerating authoritative US government estimates of parameters of infectious transmission, infection severity, and disease burden and characterizing the extent and scope of US public health affiliated epidemiological investigations published through November 2021. While we found authoritative estimates for most expected transmission and disease severity parameters, some were lacking, and others had significant uncertainties. Moreover, most transmission parameters were not validated domestically or re-assessed over the course of the pandemic. Publicly available disease surveillance measures did grow appreciably in scope and resolution over time; however, their resolution with regards to specific populations and exposure settings remained limited. We identified 283 published epidemiological reports authored by investigators affiliated with U.S. governmental public health entities. Most reported on descriptive studies. Published analytic studies did not appear to fully respond to knowledge gaps or to provide systematic evidence to support, evaluate or tailor community mitigation strategies. The existence of epidemiological data gaps 18 months after the declaration of the COVID-19 pandemic underscores the need for more timely standardization of data collection practices and for anticipatory research priorities and protocols for emerging infectious disease epidemics.

Pandemics, past and present: The role of biological anthropology in interdisciplinary pandemic studies

Biological anthropologists are ideally suited for the study of pandemics given their strengths in human biology, health, culture, and behavior, yet pandemics have historically not been a major focus of research. The COVID‐19 pandemic has reinforced the need to understand pandemic causes and unequal consequences at multiple levels. Insights from past pandemics can strengthen the knowledge base and inform the study of current and future pandemics through an anthropological lens. In this paper, we discuss the distinctive social and epidemiological features of pandemics, as well as the ways in which biological anthropologists have previously studied infectious diseases, epidemics, and pandemics. We then review interdisciplinary research on three pandemics–1918 influenza, 2009 influenza, and COVID‐19–focusing on persistent social inequalities in morbidity and mortality related to sex and gender; race, ethnicity, and Indigeneity; and pre‐existing health and disability. Following this review of the current state of pandemic research on these topics, we conclude with a discussion of ways biological anthropologists can contribute to this field moving forward. Biological anthropologists can add rich historical and cross‐cultural depth to the study of pandemics, provide insights into the biosocial complexities of pandemics using the theory of syndemics, investigate the social and health impacts of stress and stigma, and address important methodological and ethical issues. As COVID‐19 is unlikely to be the last global pandemic, stronger involvement of biological anthropology in pandemic studies and public health policy and research is vital.

Days of Flooding Associated with Increased Risk of Influenza

Influenza typically causes mild infection but can lead to severe outcomes for those with compromised lung health. Flooding, a seasonal problem in Iowa, can expose many Iowans to molds and allergens shown to alter lung inflammation, leading to asthma attacks and decreased viral clearance. Based on this, the hypothesis for this research was that there would be geographically specific positive associations in locations with flooding with influenza diagnosis. An ecological study was performed using influenza diagnoses and positive influenza polymerase chain reaction tests from a de-identified large private insurance database and Iowa State Hygienic Lab. After adjustment for multiple confounding factors, Poisson regression analysis resulted in a consistent 1% associated increase in influenza diagnoses per day above flood stage (95% confidence interval: 1.00–1.04). This relationship remained after removal of the 2009–2010 influenza pandemic year. There was no associated risk between flooding and influenza-like illness as a nonspecific diagnosis. Associated risks between flooding and increased influenza diagnoses were geographically specific, with the greatest risk in the most densely populated areas. This study indicates that populations who live, work, or volunteer in flooded environments should consider preventative measures to avoid environmental exposures to mitigate illness from influenza in the following year.

Distinct airway epithelial immune responses after infection with SARS-CoV-2 compared to H1N1

Children are less likely than adults to suffer severe symptoms when infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), while influenza A H1N1 severity is comparable across ages except for the very young or elderly. Airway epithelial cells play a vital role in the early defence against viruses via their barrier and immune functions. We investigated viral replication and immune responses in SARS-CoV-2-infected bronchial epithelial cells from healthy paediatric (n = 6; 2.5-5.6 years old) and adult (n = 4; 47-63 years old) subjects and compared cellular responses following infection with SARS-CoV-2 or Influenza A H1N1. While infection with either virus triggered robust transcriptional interferon responses, including induction of type I (IFNB1) and type III (IFNL1) interferons, markedly lower levels of interferons and inflammatory proteins (IL-6, IL-8) were released following SARS-CoV-2 compared to H1N1 infection. Only H1N1 infection caused disruption of the epithelial layer. Interestingly, H1N1 infection resulted in sustained upregulation of SARS-CoV-2 entry factors FURIN and NRP1. We did not find any differences in the epithelial response to SARS-CoV-2 infection between paediatric and adult cells. Overall, SARS-CoV-2 had diminished potential to replicate, affect morphology and evoke immune responses in bronchial epithelial cells compared to H1N1.

Outcomes and risk factors with COVID-19 or influenza in hospitalized asthma patients

BACKGROUND

At the time of the SARS-CoV-2 emergence, asthma patients were initially considered vulnerable because respiratory viruses, especially influenza, are associated with asthma exacerbations, increased risk of hospitalization and more severe disease course. We aimed to compare the asthma prevalence in patients hospitalized for COVID-19 or influenza and risk factors associated with poor prognosis with the diseases.

METHODS

This retrospective cohort study used the Paris university hospitals clinical data warehouse to identify adults hospitalized for COVID-19 (January to June 2020) or influenza (November 2017 to March 2018 for the 2017-2018 influenza period and November 2018 to March 2019 for the 2018-2019 period). Asthma patients were identified with J45 and J46 ICD-10 codes. Poor outcomes were defined as admission in intensive care or death.

RESULTS

Asthma prevalence was significantly higher among influenza than COVID-19 patients (n = 283/3 119, 9.1%, 95% CI [8.1-10.1] in 2017-2018 and n = 309/3 266, 9.5%, 95% CI [8.5-10.5] in 2018-2019 versus n = 402/9 009, 4.5%, 95% CI [4.0-4.9]). For asthma patients, 31% with COVID-19 were admitted to an intensive care unit versus 23% and 21% with influenza. Obesity was a risk factor for the 2017-2018 influenza period, smoking and heart failure for the 2018-2019 period. Among COVID-19 patients with asthma, smoking and obesity were risk factors for the severe form.

CONCLUSIONS

In this study, patients with an asthma ICD-10 code were less represented among COVID-19 patients than among influenza-infected ones. However, outcomes were poorer for COVID-19 than influenza patients, both with asthma. These data highlight the importance of protective shields and vaccination against influenza and COVID-19 in this population.

COVID-19 pandemic: lessons learned from more than a century of pandemics and current vaccine development for pandemic control

Pandemic dynamics and health care responses are markedly different during the COVID-19 pandemic than in earlier outbreaks. Compared with established infectious disease such as influenza, we currently know relatively little about the origin, reservoir, cross-species transmission and evolution of SARS-CoV-2. Health care services, drug availability, laboratory testing, research capacity and global governance are more advanced than during 20th century pandemics, although COVID-19 has highlighted significant gaps. The risk of zoonotic transmission and an associated new pandemic is rising substantially. COVID-19 vaccine development has been done at unprecedented speed, with the usual sequential steps done in parallel. The pandemic has illustrated the feasibility of this approach and the benefits of a globally coordinated response and infrastructure. Some of the COVID-19 vaccines recently developed or currently in development might offer flexibility or sufficiently broad protection to swiftly respond to antigenic drift or emergence of new coronaviruses. Yet many challenges remain, including the large-scale production of sufficient quantity of vaccines, delivery of vaccines to all countries and ensuring vaccination of relevant age groups. This wide vaccine technology approach will be best employed in tandem with active surveillance for emerging variants or new pathogens using antigen mapping, metagenomics and next generation sequencing.

Changes in characteristics and case-severity in patients hospitalised with influenza A (H1N1) pdm09 infection between two epidemic waves-England, 2009-2010

BACKGROUND

During 2009-2010, pandemic influenza A (H1N1) pdm09 virus (pH1N1) infections in England occurred in two epidemic waves. Reasons for a reported increase in case-severity during the second wave are unclear.

METHODS

We analysed hospital-based surveillance for patients with pH1N1 infections in England during 2009-2010 and linked national data sets to estimate ethnicity, socio-economic status and death within 28 days of admission. We used multivariable logistic regression to assess whether changes in demographic, clinical and management characteristics of patients could explain an increase in ICU admission or death, and accounted for missing values using multiple imputation.

RESULTS

During the first wave, 54/960 (6%) hospitalised patients required intensive care and 21/960 (2%) died; during the second wave 143/1420 (10%) required intensive care and 55/1420 (4%) died. In a multivariable model, during the second wave patients were less likely to be from an ethnic minority (OR 0.33, 95% CI 0.26-0.42), have an elevated deprivation score (OR 0.75, 95% CI 0.68-0.83), have known comorbidity (OR 0.78, 95% CI 0.63-0.97) or receive antiviral therapy ≤2 days before onset (OR 0.72, 95% CI 0.56-0.92). Increased case-severity during the second wave was not explained by changes in demographic, clinical or management characteristics.

CONCLUSIONS

Monitoring changes in patient characteristics could help target interventions during multiple waves of COVID-19 or a future influenza pandemic. To understand and respond to changes in case-severity, surveillance is needed that includes additional factors such as admission thresholds and seasonal coinfections.

Agent-Based Simulation Framework for Epidemic Forecasting during Hajj Seasons in Saudi Arabia

The religious pilgrimage of Hajj is one of the largest annual gatherings in the world. Every year approximately three million pilgrims travel from all over the world to perform Hajj in Mecca in Saudi Arabia. The high population density of pilgrims in confined settings throughout the Hajj rituals can facilitate infectious disease transmission among the pilgrims and their contacts. Infected pilgrims may enter Mecca without being detected and potentially transmit the disease to other pilgrims. Upon returning home, infected international pilgrims may introduce the disease into their home countries, causing a further spread of the disease. Computational modeling and simulation of social mixing and disease transmission between pilgrims can enhance the prevention of potential epidemics. Computational epidemic models can help public health authorities predict the risk of disease outbreaks and implement necessary intervention measures before or during the Hajj season. In this study, we proposed a conceptual agent-based simulation framework that integrates agent-based modeling to simulate disease transmission during the Hajj season from the arrival of the international pilgrims to their departure. The epidemic forecasting system provides a simulation of the phases and rituals of Hajj following their actual sequence to capture and assess the impact of each stage in the Hajj on the disease dynamics. The proposed framework can also be used to evaluate the effectiveness of the different public health interventions that can be implemented during the Hajj, including size restriction and screening at entry points.

Updating the influenza virus library at Hokkaido University -It's potential for the use of pandemic vaccine strain candidates and diagnosis

Genetic reassortment of influenza A viruses through cross-species transmission contributes to the generation of pandemic influenza viruses. To provide information on the ecology of influenza viruses, we have been conducting a global surveillance of zoonotic influenza and establishing an influenza virus library. Of 4580 influenza virus strains in the library, 3891 have been isolated from over 70 different bird species. The remaining 689 strains were isolated from humans, pigs, horses, seal, whale, and the environment. Phylogenetic analyses of the HA genes of the library isolates demonstrate that the library strains are distributed to all major known clusters of the H1, H2 and H3 subtypes of HA genes that are prevalent in humans. Since past pandemic influenza viruses are most likely genetic reassortants of zoonotic and seasonal influenza viruses, a vast collection of influenza A virus strains from various hosts should be useful for vaccine preparation and diagnosis for future pandemics.

Epigenetic susceptibility to severe respiratory viral infections and its therapeutic implications: a narrative review

The emergence of highly pathogenic strains of influenza virus and coronavirus (CoV) has been responsible for large epidemic and pandemic outbreaks characterised by severe pulmonary illness associated with high morbidity and mortality. One major challenge for critical care is to stratify and minimise the risk of multi-organ failure during the stay in the intensive care unit (ICU). Epigenetic-sensitive mechanisms, including deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) methylation, histone modifications, and non-coding RNAs may lead to perturbations of the host immune-related transcriptional programmes by regulating chromatin structure and gene expression patterns. Viruses causing severe pulmonary illness can use epigenetic-regulated mechanisms during host-pathogen interaction to interfere with innate and adaptive immunity, adequacy of inflammatory response, and overall outcome of viral infections. For example, Middle East respiratory syndrome-CoV and H5N1 can affect host antigen presentation through DNA methylation and histone modifications. The same mechanisms would presumably occur in patients with coronavirus disease 2019, in which tocilizumab may epigenetically reduce microvascular damage. Targeting epigenetic pathways by immune modulators (e.g. tocilizumab) or repurposed drugs (e.g. statins) may provide novel therapeutic opportunities to control viral-host interaction during critical illness. In this review, we provide an update on epigenetic-sensitive mechanisms and repurposed drugs interfering with epigenetic pathways which may be clinically suitable for risk stratification and beneficial for treatment of patients affected by severe viral respiratory infections.

The Effects of Imprinting and Repeated Seasonal Influenza Vaccination on Adaptive Immunity after Influenza Vaccination

(1) Background: The influenza virus continues to cause significant annual morbidity and mortality. The overall efficacy of seasonal influenza vaccination is suboptimal, which is partly due to host immune factors. The effects of imprinting and repeated seasonal influenza vaccination were investigated to assess for immune factors and mechanisms that impact influenza vaccine responses. (2) Methods: Twenty participants were enrolled into a prospective pilot study based on birth cohort and seasonal influenza immunization history. Immunologic parameters were assessed over a six-month period after the seasonal influenza vaccine was administered. (3) Results: There was no significant imprinting effect, as measured by hemagglutination inhibition (HAI) fold change, HAI geometric mean titer (GMT) for Day 29 or Day 180 post-vaccination and antigen- specific antibody-secreting cells (ASC) for Day 8 post-vaccination. Individuals who had minimal prior seasonal influenza vaccination had a higher magnitude ASC response and a higher HAI fold change post-vaccination than individuals who were repeatedly vaccinated. (4) Conclusions: Repeated seasonal influenza vaccination resulted in a decreased fold change of the immune response, although individuals in this cohort tended to have high HAI titers at baseline that persisted after vaccination. Imprinting effects were not observed in this cohort. These host immune factors should be considered in the development of universal influenza vaccines. ClinicalTrials.gov Identifier: NCT03686514.

Overrepresentation of South Asian ethnic groups among cases of influenza A(H1N1)pdm09 during the first phase of the 2009 pandemic in England

BACKGROUND

During the first wave of the influenza A(H1N1)pdm09 pandemic in England in 2009, morbidity and mortality were higher in patients of South Asian (Indian, Pakistani or Bangladeshi) ethnic minority groups.

OBJECTIVES

This study aims to provide insights in the representation of this group among reported cases, indicating susceptibility and exposure.

METHODS

All laboratory-confirmed cases including basic demographic and limited clinical information that were reported to the FluZone surveillance system between April and October 2009 were retrieved. Missing ethnicity data were imputed using the previously developed and validated South Asian Names and Group Recognition Algorithm (SANGRA). Differences between ethnic groups were calculated using chi-square, log-rank and t tests and rate ratios. Geographic clustering was compared using Ripley's K functions.

RESULTS

SANGRA identified 2447 (28%) of the total of 8748 reported cases as South Asian. South Asian cases were younger (P < .001), more often male (P = .002) and more often from deprived areas (P < .001) than cases of other ethnic groups. Time between onset of symptoms and laboratory sampling was longer in this group (P < .001), and they were less often advised antiviral treatment (P < .001), however, declined treatment less. The highest cumulative incidence was seen in the West Midlands region (32.7/10 000), London (7.0/10 000) and East of England region (5.7/10 000).

CONCLUSIONS

People of South Asian ethnic groups were disproportionally affected by the first wave of the influenza pandemic in England in 2009. The findings presented contribute to further understanding of demographic, socioeconomic and ethnic factors of the outbreak and inform future influenza preparedness to ensure appropriate prevention and care.

COVID-19 and Morbid Obesity: Associations and Consequences for Policy and Practice

While the impact of obesity on chronic disease has been widely examined, there has been less research regarding the influence of obesity on infectious diseases, particularly respiratory diseases. This exploratory research uses the currently available data on COVID‐19 cases and mortality, along with estimates of the morbidly obese populations in the United States by county, to examine the association between morbid obesity and deaths from COVID‐19 and to identify potential coincident spatial clusters of morbid obesity and COVID‐19 deaths. Results indicate a statistically significant positive correlation between population‐adjusted COVID‐19 deaths and cases and the estimated population with a body mass index ≥ 40. Clustering analyses show there is a predominant similarity in the distribution of COVID‐19 deaths and obesity. Our findings suggest it is critical to include an awareness of obesity when developing infectious disease control measures and point to a greater need to focus resources toward obesity education and policy initiatives.

Seasonal Influenza Vaccine Impact on Pandemic H1N1 Vaccine Efficacy

Background

In 2009, a novel influenza A (pH1N1) was identified, resulting in a pandemic with significant morbidity and mortality. A monovalent pH1N1 vaccine was separately produced in addition to the seasonal trivalent influenza vaccine. Formulation of the seasonal influenza vaccine (injectable trivalent inactivated influenza vaccine [TIV] vs. intranasal live, attenuated influenza vaccine [LAIV]) was postulated to have impacted the efficacy of the pH1N1 vaccination.

Methods

We reviewed electronic health and databases, which included vaccination records, and healthcare encounters for influenza-like illness (ILI), influenza, and pneumonia among US military members. We examined rates by vaccination type to identify factors associated with the risk for study outcomes.

Results

Compared with those receiving the seasonal influenza vaccine alone, subjects receiving the pH1N1 vaccine, either alone (RR, 0.49) or in addition to the seasonal vaccine (RR, 0.51), had an approximately 50% reduction in ILI, 88% reduction in influenza (RR, 0.11 and 0.12, respectively), and 63% reduction in pneumonia (RR, 0.37 and 0.35, respectively). There was no clinically significant difference in ILI, influenza, or pneumonia attack rates among those receiving the pH1N1 vaccine with or without presence of the seasonal vaccine. Similarly, there was no clinically relevant difference in pH1N1 effectiveness between seasonal TIV and LAIV recipients.

Conclusions

During the 2009–2010 pandemic, the pH1N1 vaccination was effective in reducing rates of ILI, influenza, and pneumonia. Administration of the seasonal vaccine should continue without concern of potential interference with a novel pandemic vaccine, though more studies are needed to determine if this is applicable to other influenza seasons.

Age-dependent effects in the transmission and control of COVID-19 epidemics

The COVID-19 pandemic has shown a markedly low proportion of cases among children^1-4. Age disparities in observed cases could be explained by children having lower susceptibility to infection, lower propensity to show clinical symptoms or both. We evaluate these possibilities by fitting an age-structured mathematical model to epidemic data from China, Italy, Japan, Singapore, Canada and South Korea. We estimate that susceptibility to infection in individuals under 20 years of age is approximately half that of adults aged over 20 years, and that clinical symptoms manifest in 21% (95% credible interval: 12-31%) of infections in 10- to 19-year-olds, rising to 69% (57-82%) of infections in people aged over 70 years. Accordingly, we find that interventions aimed at children might have a relatively small impact on reducing SARS-CoV-2 transmission, particularly if the transmissibility of subclinical infections is low. Our age-specific clinical fraction and susceptibility estimates have implications for the expected global burden of COVID-19, as a result of demographic differences across settings. In countries with younger population structures-such as many low-income countries-the expected per capita incidence of clinical cases would be lower than in countries with older population structures, although it is likely that comorbidities in low-income countries will also influence disease severity. Without effective control measures, regions with relatively older populations could see disproportionally more cases of COVID-19, particularly in the later stages of an unmitigated epidemic.

H1N1 Infection Reduces Glucose Level in Human U937 Monocytes Culture

Infection with influenza A (H1N1) virus contributes significantly to the global burden of acute respiratory diseases. Glucose uptake and metabolic changes are reported in different cell types after infections with different virus types, including influenza A virus. Alteration of glucose metabolism specifically in immune cells has major health consequences. The aim of this study was to monitor glucose concentration in unstimulated and stimulated U937 human monocytes with infectious or heat inactivated H1N1 or Staphylococcus aureus or in nonpathogenically stimulated monocytes with phorbol-12-myristate-13-acetate. Stimulated or unstimulated U937 human monocytes were subjected to H1N1 infection for different time points and the glucose profile in the growth medium was measured post infection. Results showed that regardless to whether the initial stimuli on U937 cells were of pathogen or nonpathogen origins, challenge infection by H1N1 causes a significant reduction of glucose levels 36 h post infection. In conclusion, H1N1 infection has a direct effect on the glucose uptake of U937 cells in vitro. This effect can be related to either H1N1 infection or cell differentiation status that might occur due to the exerted stimuli.

Symbolic transfer entropy reveals the age structure of pandemic influenza transmission from high-volume influenza-like illness data

Existing methods to infer the relative roles of age groups in epidemic transmission can normally only accommodate a few age classes, and/or require data that are highly specific for the disease being studied. Here, symbolic transfer entropy (STE), a measure developed to identify asymmetric transfer of information between stochastic processes, is presented as a way to reveal asymmetric transmission patterns between age groups in an epidemic. STE provides a ranking of which age groups may dominate transmission, rather than a reconstruction of the explicit between-age-group transmission matrix. Using simulations, we establish that STE can identify which age groups dominate transmission even when there are differences in reporting rates between age groups and even if the data are noisy. Then, the pairwise STE is calculated between time series of influenza-like illness for 12 age groups in 884 US cities during the autumn of 2009. Elevated STE from 5 to 19 year-olds indicates that school-aged children were likely the most important transmitters of infection during the autumn wave of the 2009 pandemic in the USA. The results may be partially confounded by higher rates of physician-seeking behaviour in children compared to adults, but it is unlikely that differences in reporting rates can explain the observed differences in STE.

State-level estimates of excess hospitalizations and deaths associated with influenza

Background

National estimates of influenza burden may not reflect state‐level influenza activity, and local surveillance may not capture the full burden of influenza.

Methods

To provide state‐level information about influenza burden, we estimated excess pneumonia and influenza (P&I) and respiratory and circulatory (R&C) hospitalizations and deaths in Colorado from local hospital discharge records, death certificates, and influenza virus surveillance using negative binomial models.

Results

From July 2007 to June 2016, influenza was associated with an excess of 17 911 P&I hospitalizations (95%CI: 15 227, 20 354), 30 811 R&C hospitalizations (95%CI: 24 344, 37 176), 1,064 P&I deaths (95%CI: 757, 1298), and 3828 R&C deaths (95%CI: 2060, 5433). There was a large burden of influenza A(H1N1) among persons aged 0‐64 years, with high median seasonal rates of excess hospitalization among persons aged 0‐4 years. Persons aged ≥65 years experienced the largest numbers and highest median seasonal rates of excess hospitalization and death associated with influenza A (H3N2). The burden of influenza B was generally lower, with elevated median seasonal rates of excess hospitalization among persons aged 0‐4 years and ≥65 years.

Conclusions

These findings complement existing influenza surveillance. Periodic state‐level estimates of influenza disease burden may be useful for setting state public health priorities and planning prevention and control initiatives.

Characteristics of hospitalised patients with influenza in 2015-2016 in northern Israel: three circulating strains and continued fear of 2009 A/H1N1

This study aimed to characterise children and adults diagnosed with influenza who were admitted to three medical centres in northern Israel in the winter of 2015-2016, a unique season due to infection with three types of influenza strains: A/H1N1, A/non-H1N1 and B. Data were collected retrospectively from medical records. Influenza A/H1N1 infected mainly adults (61% vs. 16% in children, P < 0.001) while influenza B was the common type in children (54% vs. 28% in adults, P < 0.001). Adults (36% vs. 5% in children, P < 0.001) and patients infected with A/H1N1 had higher rates of pneumonia (34% vs. 16% and 14% in influenza B and A/non-H1N1, respectively, P = 0.002). Treatment with oseltamivir was prescribed to 90% of patients; adults had higher rates of treatment (96% vs. 84% in children, P = 0.002) as well as patients infected with A/H1N1 (96% vs. 86% in influenza B and A/non-H1N1, respectively, P = 0.04). Oseltamivir was given after a mean of 3.6 days of symptoms. Preferential infection of adults by A/H1N1 was evident in Israel in 2015-2016; pneumonia rates were higher in adults and in A/H1N1-infected patients. Oseltamivir was prescribed to most patients but especially to those infected with A/H1N1, and was given relatively late in the course of the disease.

Deep sequencing of 2009 influenza A/H1N1 virus isolated from volunteer human challenge study participants and natural infections

Nasal wash samples from 15 human volunteers challenged with GMP manufactured influenza A/California/04/2009(H1N1) and from 5 naturally infected influenza patients of the 2009 pandemic were deep sequenced using viral targeted hybridization enrichment. Ten single nucleotide polymorphism (SNP) positions were found in the challenge virus. Some of the nonsynonymous changes in the inoculant virus were maintained in some challenge participants, but not in others, indicating that virus is evolving away from the Vero cell adapted inoculant, for example SNPs in the neuraminidase. Many SNP sites in challenge patients and naturally infected patients were found, many not identified previously. The SNPs identified, and phylogenetic analyses, showed that intrahost evolution of the virus are different in challenge participants and naturally infected patients. This study, using hybridization enrichment without PCR, provided an accurate and unbiased assessment of differential intrahost viral evolution from a uniform influenza inoculant in humans and comparison to naturally infected patients.

Two-strain epidemic model involving fractional derivative with Mittag-Leffler kernel

In the present study, the fractional version with respect to the Atangana-Baleanu fractional derivative operator in the caputo sense (ABC) of the two-strain epidemic mathematical model involving two vaccinations has extensively been analyzed. Furthermore, using the fixed-point theory, it has been shown that the solution of the proposed fractional version of the mathematical model does not only exist but is also the unique solution under some conditions. The original mathematical model consists of six first order nonlinear ordinary differential equations, thereby requiring a numerical treatment for getting physical interpretations. Likewise, its fractional version is not possible to be solved by any existing analytical method. Therefore, in order to get the observations regarding the output of the model, it has been solved using a newly developed convergent numerical method based on the Atangana-Baleanu fractional derivative operator in the caputo sense. To believe upon the results obtained, the fractional order α has been allowed to vary between ( 0 , 1 ] , whereupon the physical observations match with those obtained in the classical case, but the fractional model has persisted all the memory effects making the model much more suitable when presented in the structure of fractional order derivatives for ABC. Finally, the fractional forward Euler method in the classical caputo sense has been used to illustrate the better performance of the numerical method obtained via the Atangana-Baleanu fractional derivative operator in the caputo sense.

Public Health Emergency Preparedness System Evaluation Criteria and Performance Metrics: A Review of Contributions of the CDC-Funded Preparedness and Emergency Response Research Centers

OBJECTIVES

The US Centers for Disease Control and Prevention (CDC)-funded Preparedness and Emergency Response Research Centers (PERRCs) conducted research from 2008 to 2015 aimed to improve the complex public health emergency preparedness and response (PHEPR) system. This paper summarizes PERRC studies that addressed the development and assessment of criteria for evaluating PHEPR and metrics for measuring their efficiency and effectiveness.

METHODS

We reviewed 171 PERRC publications indexed in PubMed between 2009 and 2016. These publications derived from 34 PERRC research projects. We identified publications that addressed the development or assessment of criteria and metrics pertaining to PHEPR systems and describe the evaluation methods used and tools developed, the system domains evaluated, and the metrics developed or assessed.

RESULTS

We identified 29 publications from 12 of the 34 PERRC projects that addressed PHEPR system evaluation criteria and metrics. We grouped each study into 1 of 3 system domains, based on the metrics developed or assessed: (1) organizational characteristics (n = 9), (2) emergency response performance (n = 12), and (3) workforce capacity or capability (n = 8). These studies addressed PHEPR system activities including responses to the 2009 H1N1 pandemic and the 2011 tsunami, as well as emergency exercise performance, situational awareness, and workforce willingness to respond. Both PHEPR system process and outcome metrics were developed or assessed by PERRC studies.

CONCLUSIONS

PERRC researchers developed and evaluated a range of PHEPR system evaluation criteria and metrics that should be considered by system partners interested in assessing the efficiency and effectiveness of their activities. Nonetheless, the monitoring and measurement problem in PHEPR is far from solved. Lack of standard measures that are readily obtained or computed at local levels remains a challenge for the public health preparedness field. (Disaster Med Public Health Preparedness. 2019;13:626-638).

Transmissibility of emerging viral zoonoses

Effective public health research and preparedness requires an accurate understanding of which virus species possess or are at risk of developing human transmissibility. Unfortunately, our ability to identify these viruses is limited by gaps in disease surveillance and an incomplete understanding of the process of viral adaptation. By fitting boosted regression trees to data on 224 human viruses and their associated traits, we developed a model that predicts the human transmission ability of zoonotic viruses with over 84% accuracy. This model identifies several viruses that may have an undocumented capacity for transmission between humans. Viral traits that predicted human transmissibility included infection of nonhuman primates, the absence of a lipid envelope, and detection in the human nervous system and respiratory tract. This predictive model can be used to prioritize high-risk viruses for future research and surveillance, and could inform an integrated early warning system for emerging infectious diseases.

Evaluation of a Field-Deployable Insulated Isothermal Polymerase Chain Reaction Nucleic Acid Analyzer for Influenza A Virus Detection at Swine Exhibitions

Rapid detection of influenza A virus (IAV) at swine exhibitions, where zoonotic transmission has occurred, can allow exhibition officials to quickly implement mitigation strategies and reduce public health risk. While laboratory diagnostic methods using PCR exist, pen-side detection of IAV can reduce lag time between sample collection and results. Portable insulated isothermal PCR (RT-iiPCR) has been used for point-of-care pathogen detection in veterinary medicine. This study compared laboratory methods of real-time reverse transcription PCR (rRT-PCR) to RT-iiPCR to determine the potential effectiveness of RT-iiPCR for detection of IAV in swine in the field. Two methods of extraction (magnetic bead and spin-column) and the two PCR platforms were used in a crossover study design to detect IAV in nasal wipes of 150 individual swine from one exhibition. Magnetic bead extraction is considered the laboratory gold standard while spin-column purification is considered the field-deployable method. IAV RNA was detected in 17 samples using Mag/rRT-PCR (reference assay) and 16 samples using Mag/RT-iiPCR (Sensitivity-S 76.5%), whereas only 14 samples using Spin/rRT-PCR (S 88.2%) and 12 samples using Spin/RT-iiPCR (field method) (S 58.8%) were positive, demonstrating a reduction in detection of viral RNA using column purification. There is moderate agreement (Cohen's kappa = 0.6575) between Mag/rRT-PCR and Spin/RT-iiPCR. There is good agreement between both PCR assays when using the same method of extraction (Mag: Cohen's kappa = 0.8203, Spin: Cohen's kappa = 0.7642). RT-iiPCR requires testing of 10 more samples than the rRT-PCR to detect disease at the 95% confidence level in a population of 300 animals with a disease prevalence of 20%. In conclusion, although there is some reduction in sensitivity, RT-iiPCR used in conjunction with spin-column purification is an acceptable method of IAV in swine detection at exhibitions where it may help reduce lag time and allow for rapid control of an IAV outbreak.

Real-Time Surveillance of Influenza Morbidity: Tracking Intensive Care Unit Resource Utilization

RATIONALE

Existing real-time surveillance of influenza morbidity, based primarily on time-trended U.S. hospitalization and death data, is inadequate. These surveillance methods do not accurately predict hospital resource requirements or sufficiently capture the public health impact of the current influenza season.

OBJECTIVES

To determine the feasibility and potential usefulness of tracking surrogate markers of influenza morbidity among patients hospitalized with influenza.

METHODS

We performed a pilot study at three tertiary care referral hospitals and retrospectively collected and analyzed data on patients admitted with influenza during the 2013-2014 influenza season. We analyzed traditional influenza surveillance metrics, including weekly statistics on admissions and deaths, as well as weekly rates and trends of intensive care unit (ICU), mechanical ventilation, and extracorporeal membrane oxygenation (ECMO) utilization.

RESULTS

In our three-hospital cohort, 431 patients were hospitalized with influenza and spent a total of 1,520 days in ICUs. Eighty-six (20%) of these patients required 1,080 days of mechanical ventilation, and 17 patients (4%) received 229 days of ECMO. Trends of ICU and mechanical ventilation use were similar but differed notably from trends of ECMO use, hospitalization, and death. In particular, at two hospitals, increases in utilization of ICU and mechanical ventilation among patients with influenza occurred several weeks after increases in hospitalization rates. Furthermore, ICU, mechanical ventilation, and ECMO utilization rates at the three-hospital network remained elevated for several weeks after the influenza-associated hospitalization rate declined.

CONCLUSIONS

Surrogate markers of influenza severity were feasible to collect and revealed trends of ICU resource utilization that differed notably from trends of hospitalization and death given by traditional influenza surveillance metrics. A national network of sentinel hospitals that prospectively collects, time-trends, and reports additional influenza morbidity data would be useful to hospital administrators, hospital epidemiologists, infection preventionists, and public health officials.

Influenza Vaccination Modifies Disease Severity Among Community-dwelling Adults Hospitalized With Influenza

Background

We investigated the effect of influenza vaccination on disease severity in adults hospitalized with laboratory-confirmed influenza during 2013-14, a season in which vaccine viruses were antigenically similar to those circulating.

Methods

We analyzed data from the 2013-14 influenza season and used propensity score matching to account for the probability of vaccination within age strata (18-49, 50-64, and ≥65 years). Death, intensive care unit (ICU) admission, and hospital and ICU lengths of stay (LOS) were outcome measures for severity. Multivariable logistic regression and competing risk models were used to compare disease severity between vaccinated and unvaccinated patients, adjusting for timing of antiviral treatment and time from illness onset to hospitalization.

Results

Influenza vaccination was associated with a reduction in the odds of in-hospital death among patients aged 18-49 years (adjusted odds ratios [aOR] = 0.21; 95% confidence interval [CI], 0.05 to 0.97), 50-64 years (aOR = 0.48; 95% CI, 0.24 to 0.97), and ≥65 years (aOR = 0.39; 95% CI, 0.17 to 0.66). Vaccination also reduced ICU admission among patients aged 18-49 years (aOR = 0.63; 95% CI, 0.42 to 0.93) and ≥65 years (aOR = 0.63; 95% CI, 0.48 to 0.81), and shortened ICU LOS among those 50-64 years (adjusted relative hazards [aRH] = 1.36; 95% CI, 1.06 to 1.74) and ≥65 years (aRH = 1.34; 95% CI, 1.06 to 1.73), and hospital LOS among 50-64 years (aRH = 1.13; 95% CI, 1.02 to 1.26) and ≥65 years (aRH = 1.24; 95% CI, 1.13 to 1.37).

Conclusions

Influenza vaccination during 2013-14 influenza season attenuated adverse outcome among adults that were hospitalized with laboratory-confirmed influenza.

Race-related differences in antibody responses to the inactivated influenza vaccine are linked to distinct pre-vaccination gene expression profiles in blood

We conducted a 5-year study analyzing antibody and B cell responses to the influenza A virus components of the inactivated influenza vaccine, trivalent (IIV3) or quadrivalent (IIV4) in younger (aged 35-45) and aged (≥65 years of age) Caucasian and African American individuals. Antibody titers to the two influenza A virus strains, distribution of circulating B cell subsets and the blood transcriptome were tested at baseline and after vaccination while expression of immunoregulatory markers on B cells were analyzed at baseline. African Americans mounted higher virus neutralizing and IgG antibody responses to the H1N1 component of IIV3 or 4 compared to Caucasians. African Americans had higher levels of circulating B cell subsets compared to Caucasians. Expression of two co-regulators, i.e., programmed death (PD)-1 and the B and T cell attenuator (BTLA) were differentially expressed in the two cohorts. Race-related differences were caused by samples from younger African Americans, while results obtained with samples of aged African Americans were similar to those of aged Caucasians. Gene expression profiling by Illumina arrays revealed highly significant differences in 1368 probes at baseline between Caucasians and African Americans although samples from both cohorts showed comparable changes in transcriptome following vaccination. Genes differently expressed between samples from African Americans and Caucasians regardless of age were enriched for myeloid genes, while the transcripts that differed in expression between younger African Americans and younger Caucasians were enriched for those specific for B-cells.

Enterovirus D68 Infection Among Children With Medically Attended Acute Respiratory Illness, Cincinnati, Ohio, July-October 2014

Background

Enterovirus D68 (EV-D68) caused a widespread outbreak of respiratory illness in the United States in 2014, predominantly affecting children. We describe EV-D68 rates, spectrum of illness, and risk factors from prospective, population-based acute respiratory illness (ARI) surveillance at a large US pediatric hospital.

Methods

Children <13 years of age with ARI and residence in Hamilton County, Ohio were enrolled from the inpatient and emergency department (ED) settings at a children's hospital in Cincinnati, Ohio, from 1 July to 31 October 2014. For each participant, we interviewed parents, reviewed medical records, and tested nasal and throat swabs for EV-D68 using real-time reverse- transcription polymerase chain reaction assay.

Results

EV-D68 infection was detected in 51 of 207 (25%) inpatients and 58 of 505 (11%) ED patients. Rates of EV-D68 hospitalization and ED visit were 1.3 (95% confidence interval [CI], 1.0-1.6) and 8.4 per 1000 children <13 years of age, respectively. Preexisting asthma was associated with EV-D68 infection (adjusted odds ratio, 3.2; 95% CI, 2.0-5.1). Compared with other ARI, children with EV-D68 were more likely to be admitted from the ED (P ≤ .001), receive supplemental oxygen (P = .001), and require intensive care unit admission (P = .04); however, mechanical ventilation was uncommon (2/51 inpatients; P = .64), and no deaths occurred.

Conclusions

During the 2014 EV-D68 epidemic, high rates of pediatric hospitalizations and ED visits were observed. Children with asthma were at increased risk for medically attended EV-D68 illness. Preparedness planning for a high-activity EV-D68 season in the United States should take into account increased healthcare utilization, particularly among children with asthma, during the late summer and early fall.

Bursting endemic bubbles in an adaptive network

The spread of an infectious disease is known to change people's behavior, which in turn affects the spread of disease. Adaptive network models that account for both epidemic and behavioral change have found oscillations, but in an extremely narrow region of the parameter space, which contrasts with intuition and available data. In this paper we propose a simple susceptible-infected-susceptible epidemic model on an adaptive network with time-delayed rewiring, and show that oscillatory solutions are now present in a wide region of the parameter space. Altering the transmission or rewiring rates reveals the presence of an endemic bubble—an enclosed region of the parameter space where oscillations are observed.

Heterogeneity in Estimates of the Impact of Influenza on Population Mortality: A Systematic Review

Influenza viruses are associated with a substantial global burden of morbidity and mortality every year. Estimates of influenza-associated mortality often vary between studies due to differences in study settings, methods, and measurement of outcomes. We reviewed 103 published articles assessing population-based influenza-associated mortality through searches of PubMed and Embase, and we identified considerable variation in the statistical methods used across studies. Studies using regression models with an influenza activity proxy applied 4 approaches to estimate influenza-associated mortality. The estimates increased with age and ranged widely, from -0.3-1.3 and 0.6-8.3 respiratory deaths per 100,000 population for children and adults, respectively, to 4-119 respiratory deaths per 100,000 population for older adults. Meta-regression analysis identified that study design features were associated with the observed variation in estimates. The estimates increased with broader cause-of-death classification and were higher for older adults than for children. The multiplier methods tended to produce lower estimates, while Serfling-type models were associated with higher estimates than other methods. No "average" estimate of excess mortality could reliably be made due to the substantial variability of the estimates, partially attributable to methodological differences in the studies. Standardization of methodology in estimation of influenza-associated mortality would permit improved comparisons in the future.

ICU-treated influenza A(H1N1) pdm09 infections more severe post pandemic than during 2009 pandemic: a retrospective analysis

BACKGROUND

We compared in a single mixed intensive care unit (ICU) patients with influenza A(H1N1) pdm09 between pandemic and postpandemic periods.

METHODS

Retrospective analysis of prospectively collected data in 2009-2016. Data are expressed as median (25th-75th percentile) or number (percentile).

RESULTS

Seventy-six influenza A(H1N1) pdm09 patients were admitted to the ICU: 16 during the pandemic period and 60 during the postpandemic period. Postpandemic patients were significantly older (60 years vs. 43 years, p < 0.001) and less likely to have epilepsy or other neurological diseases compared with pandemic patients (5 [8.3%] vs. 6 [38%], respectively; p = 0.009). Postpandemic patients were more likely than pandemic patients to have cardiovascular disease (24 [40%] vs. 1 [6%], respectively; p = 0.015), and they had higher scores on APACHE II (17 [13-22] vs. 14 [10-17], p = 0.002) and SAPS II (40 [31-51] vs. 31 [25-35], p = 0.002) upon admission to the ICU. Postpandemic patients had higher maximal SOFA score (9 [5-12] vs. 5 [4-9], respectively; p = 0.03) during their ICU stay. Postpandemic patients had more often septic shock (40 [66.7%] vs. 8 [50.0%], p = 0.042), and longer median hospital stays (15.0 vs. 8.0 days, respectively; p = 0.006). During 2015-2016, only 18% of the ICU- treated patients had received seasonal influenza vaccination.

CONCLUSIONS

Postpandemic ICU-treated A(H1N1) pdm09 influenza patients were older and developed more often septic shock and had longer hospital stays than influenza patients during the 2009 pandemic.

Antibody-dependent phagocytosis (ADP) responses following trivalent inactivated influenza vaccination of younger and older adults

Globally the most commonly utilised immunisation against influenza is the trivalent inactivated influenza vaccine (TIV) derived from an A/H1N1, an A/H3N2 and aB type influenza virus. Vaccine effectiveness of TIV varies year to year, depending on how well antigenically matched the strains in the vaccine are compared to circulating strains [1,2]. Moreover, vaccine effectiveness can vary within certain subpopulations such as HIV-positive, young children and the elderly. Decreased vaccine effectiveness in the elderly is associated with impaired Ab production, as measured by standard hemagglutination inhibition (HAI) assays. We investigated the level of Antibody Dependent Phagocytosis (ADP)-mediating Abs induced by the 2008-TIV in healthy Australian adults aged over and under 60years to determine if this immune function was also reduced in the elderly. We utilised an ADP assay that measures the uptake of IgG-opsonised HA-coated fluorescent microspheres by a monocytic cell line. We also measured HA-specific Abs that are close enough to bind to dimeric FcγRIIa ectodomains in an ELISA-based assay. Furthermore, we compared the extent of cross-reactive recognition of diverse influenza strains by ADP-mediating Abs found in pre- and post-vaccination sera in both of these groups. We found that young adults and older adults mounted similar ADP activity against HAs contained in the 2008-TIV, despite older adults have diminished HI responses. The level of cross-reactive antibodies against other HAs was limited in both groups. We conclude that seasonal influenza vaccination elicits limited cross-reactive ADP to HA in both young and older adults. New influenza vaccination strategies that elicit cross-reactive and polyfunctional antibodies are needed.

Extracorporeal membrane oxygenation in acute respiratory distress syndrome due to influenza A (H1N1)pdm09 pneumonia. A single-center experience during the 2013-2014 season

Objective

This report aimed to describe the outcomes of the patients with severe H1N1 associated acute respiratory distress syndrome who were treated with extracorporeal membrane oxygenation therapy.

Methods

This retrospective review analyzed a single-center cohort of adult patients with H1N1-related acute respiratory distress syndrome who were managed with veno-venous extracorporeal membrane oxygenation during the winter of 2013/2014.

Results

A total of 10 patients received veno-venous extracorporeal membrane oxygenation for H1N1 influenza between January 2013 and March 2014. Seven patients were transferred to our center for extracorporeal membrane oxygenation consideration (all within 72 hours of initiating mechanical ventilation). The median patient age was forty years, and 30% were female. The median arterial oxygen partial pressure to fraction of inspired oxygen ratio was 62.5, and the median RESP score was 6. Three patients received inhaled nitric oxide, and four patients were proned as rescue therapy before extracorporeal membrane oxygenation was initiated. The median duration of mechanical ventilation was twenty-two days (range, 14 - 32). The median length of stay in the intensive care unit was twenty-seven days (range, 14 - 39). The median hospital length of stay was 29.1 days (range, 16.0 - 46.9). Minor bleeding complications occurred in 6 of 10 patients. Eight of the ten patients survived to hospital discharge.

Conclusion

The survivors were relatively young and discharged with good functional status (i.e., enhancing quality-adjusted life-years-saved). Our experience shows that even a relatively new extracorporeal membrane oxygenation program can play an important role in that capacity and provide excellent outcomes for the sickest patients.

Epidemiological and economic impact of pandemic influenza in Chicago: Priorities for vaccine interventions

The study objective is to estimate the epidemiological and economic impact of vaccine interventions during influenza pandemics in Chicago, and assist in vaccine intervention priorities. Scenarios of delay in vaccine introduction with limited vaccine efficacy and limited supplies are not unlikely in future influenza pandemics, as in the 2009 H1N1 influenza pandemic. We simulated influenza pandemics in Chicago using agent-based transmission dynamic modeling. Population was distributed among high-risk and non-high risk among 0–19, 20–64 and 65+ years subpopulations. Different attack rate scenarios for catastrophic (30.15%), strong (21.96%), and moderate (11.73%) influenza pandemics were compared against vaccine intervention scenarios, at 40% coverage, 40% efficacy, and unit cost of $28.62. Sensitivity analysis for vaccine compliance, vaccine efficacy and vaccine start date was also conducted. Vaccine prioritization criteria include risk of death, total deaths, net benefits, and return on investment. The risk of death is the highest among the high-risk 65+ years subpopulation in the catastrophic influenza pandemic, and highest among the high-risk 0–19 years subpopulation in the strong and moderate influenza pandemics. The proportion of total deaths and net benefits are the highest among the high-risk 20–64 years subpopulation in the catastrophic, strong and moderate influenza pandemics. The return on investment is the highest in the high-risk 0–19 years subpopulation in the catastrophic, strong and moderate influenza pandemics. Based on risk of death and return on investment, high-risk groups of the three age group subpopulations can be prioritized for vaccination, and the vaccine interventions are cost saving for all age and risk groups. The attack rates among the children are higher than among the adults and seniors in the catastrophic, strong, and moderate influenza pandemic scenarios, due to their larger social contact network and homophilous interactions in school. Based on return on investment and higher attack rates among children, we recommend prioritizing children (0–19 years) and seniors (65+ years) after high-risk groups for influenza vaccination during times of limited vaccine supplies. Based on risk of death, we recommend prioritizing seniors (65+ years) after high-risk groups for influenza vaccination during times of limited vaccine supplies.

The study objective is to estimate the epidemiological and economic impact of vaccine interventions during an influenza pandemic in Chicago, to assist in vaccine intervention priorities. Population dynamics play an important role in influenza pandemic planning and response. To optimally allocate limited vaccine resources, it is important to inform decision makers and public health officials about both the direct benefit among vaccinated population and the indirect benefit among non-vaccinated population. This study adds to the evidence of prior studies by using a detailed agent-based model for estimating the direct and indirect benefits of epidemiological and economic impact of vaccine-based interventions. This study can be extended to analyze for a range of vaccine compliance and efficacy values at different attack rates of influenza pandemics in different rural and urban areas of the United States and at the country level, to infer objective prioritization criteria for influenza vaccine interventions among different risk and age groups.

A Role for Neutrophils in Viral Respiratory Disease

Neutrophils are immune cells that are well known to be present during many types of lung diseases associated with acute respiratory distress syndrome (ARDS) and may contribute to acute lung injury. Neutrophils are poorly studied with respect to viral infection, and specifically to respiratory viral disease. Influenza A virus (IAV) infection is the cause of a respiratory disease that poses a significant global public health concern. Influenza disease presents as a relatively mild and self-limiting although highly pathogenic forms exist. Neutrophils increase in the respiratory tract during infection with mild seasonal IAV, moderate and severe epidemic IAV infection, and emerging highly pathogenic avian influenza (HPAI). During severe influenza pneumonia and HPAI infection, the number of neutrophils in the lower respiratory tract is correlated with disease severity. Thus, comparative analyses of the relationship between IAV infection and neutrophils provide insights into the relative contribution of host and viral factors that contribute to disease severity. Herein, we review the contribution of neutrophils to IAV disease pathogenesis and to other respiratory virus infections.

Community Mitigation Guidelines to Prevent Pandemic Influenza - United States, 2017

When a novel influenza A virus with pandemic potential emerges, nonpharmaceutical interventions (NPIs) often are the most readily available interventions to help slow transmission of the virus in communities, which is especially important before a pandemic vaccine becomes widely available. NPIs, also known as community mitigation measures, are actions that persons and communities can take to help slow the spread of respiratory virus infections, including seasonal and pandemic influenza viruses.These guidelines replace the 2007 Interim Pre-pandemic Planning Guidance: Community Strategy for Pandemic Influenza Mitigation in the United States - Early, Targeted, Layered Use of Nonpharmaceutical Interventions (https://stacks.cdc.gov/view/cdc/11425). Several elements remain unchanged from the 2007 guidance, which described recommended NPIs and the supporting rationale and key concepts for the use of these interventions during influenza pandemics. NPIs can be phased in, or layered, on the basis of pandemic severity and local transmission patterns over time. Categories of NPIs include personal protective measures for everyday use (e.g., voluntary home isolation of ill persons, respiratory etiquette, and hand hygiene); personal protective measures reserved for influenza pandemics (e.g., voluntary home quarantine of exposed household members and use of face masks in community settings when ill); community measures aimed at increasing social distancing (e.g., school closures and dismissals, social distancing in workplaces, and postponing or cancelling mass gatherings); and environmental measures (e.g., routine cleaning of frequently touched surfaces).Several new elements have been incorporated into the 2017 guidelines. First, to support updated recommendations on the use of NPIs, the latest scientific evidence available since the influenza A (H1N1)pdm09 pandemic has been added. Second, a summary of lessons learned from the 2009 H1N1 pandemic response is presented to underscore the importance of broad and flexible prepandemic planning. Third, a new section on community engagement has been included to highlight that the timely and effective use of NPIs depends on community acceptance and active participation. Fourth, to provide new or updated pandemic assessment and planning tools, the novel influenza virus pandemic intervals tool, the Influenza Risk Assessment Tool, the Pandemic Severity Assessment Framework, and a set of prepandemic planning scenarios are described. Finally, to facilitate implementation of the updated guidelines and to assist states and localities with prepandemic planning and decision-making, this report links to six supplemental prepandemic NPI planning guides for different community settings that are available online (https://www.cdc.gov/nonpharmaceutical-interventions).

Community Mitigation Guidelines to Prevent Pandemic Influenza - United States, 2017

When a novel influenza A virus with pandemic potential emerges, nonpharmaceutical interventions (NPIs) often are the most readily available interventions to help slow transmission of the virus in communities, which is especially important before a pandemic vaccine becomes widely available. NPIs, also known as community mitigation measures, are actions that persons and communities can take to help slow the spread of respiratory virus infections, including seasonal and pandemic influenza viruses.These guidelines replace the 2007 Interim Pre-pandemic Planning Guidance: Community Strategy for Pandemic Influenza Mitigation in the United States - Early, Targeted, Layered Use of Nonpharmaceutical Interventions (https://stacks.cdc.gov/view/cdc/11425). Several elements remain unchanged from the 2007 guidance, which described recommended NPIs and the supporting rationale and key concepts for the use of these interventions during influenza pandemics. NPIs can be phased in, or layered, on the basis of pandemic severity and local transmission patterns over time. Categories of NPIs include personal protective measures for everyday use (e.g., voluntary home isolation of ill persons, respiratory etiquette, and hand hygiene); personal protective measures reserved for influenza pandemics (e.g., voluntary home quarantine of exposed household members and use of face masks in community settings when ill); community measures aimed at increasing social distancing (e.g., school closures and dismissals, social distancing in workplaces, and postponing or cancelling mass gatherings); and environmental measures (e.g., routine cleaning of frequently touched surfaces).Several new elements have been incorporated into the 2017 guidelines. First, to support updated recommendations on the use of NPIs, the latest scientific evidence available since the influenza A (H1N1)pdm09 pandemic has been added. Second, a summary of lessons learned from the 2009 H1N1 pandemic response is presented to underscore the importance of broad and flexible prepandemic planning. Third, a new section on community engagement has been included to highlight that the timely and effective use of NPIs depends on community acceptance and active participation. Fourth, to provide new or updated pandemic assessment and planning tools, the novel influenza virus pandemic intervals tool, the Influenza Risk Assessment Tool, the Pandemic Severity Assessment Framework, and a set of prepandemic planning scenarios are described. Finally, to facilitate implementation of the updated guidelines and to assist states and localities with prepandemic planning and decision-making, this report links to six supplemental prepandemic NPI planning guides for different community settings that are available online (https://www.cdc.gov/nonpharmaceutical-interventions).

Epidemiological and Virological Characteristics of Influenza in Chongqing, China, 2011-2015

Background

Chongqing is the largest municipality and located in Southwestern of China, with over 30 million registered inhabitants. There are few reports regarding the epidemiology of influenza in Chongqing. The objective of the paper is to explore the epidemiology of influenza in Chongqing, in order to provide scientific basis for prevention and control of influenza.

Methodology /Principal Findings

From 2011 to 2015, we collected information on influenza-like illness (ILI) patients fulfilling the case definition, and took nasalpharyngeal or throat swabs specimens from ILI cases per week at the 7 sentinel hospitals. Specimens were tested by reverse transcription-polymerase chain reaction(RT-PCR) for influenza. Descriptive epidemiology was applied to analyze the epidemiology and etiology of influenza. A total of 9,696,212 cases were enrolled, of which 111,589 were ILI. Of those 24,868 samples from ILI cases, 13.3% (3,314/24,868) tested positive for influenza virus (65.7% influenza A, 34.1% influenza B, and 0.2% influenza A and B co-infection). Among the influenza A viruses, 71.3% were seasonal influenza A(H3N2) and 28.7% were influenza A(H1N1)pdm09. No cases of seasonal A(H1N1) were detected. The isolation rate was highest in children aged 5–14 years old. Influenza activity consistently peaked during January-March in 2011–2015, and June-July in 2012, 2014 and 2015.

Conclusions

Influenza is an important public health problem among ILI patients in Chongqing, especially among school-aged children. It might be beneficial to prioritize influenza vaccination for school-aged children and implement the school-based intervention to prevent and mitigating influenza outbreaks in Chongqing, particularly during the seasonal peaks.

Detecting a trend change in cross-border epidemic transmission

A method for a system of Langevin equations is developed for detecting a trend change in cross-border epidemic transmission. The equations represent a standard epidemiological SIR compartment model and a meta-population network model. The method analyzes a time series of the number of new cases reported in multiple geographical regions. The method is applicable to investigating the efficacy of the implemented public health intervention in managing infectious travelers across borders. It is found that the change point of the probability of travel movements was one week after the WHO worldwide alert on the SARS outbreak in 2003. The alert was effective in managing infectious travelers. On the other hand, it is found that the probability of travel movements did not change at all for the flu pandemic in 2009. The pandemic did not affect potential travelers despite the WHO alert.

Dynamic patterns of circulating influenza virus from 2005 to 2012 in Shandong Province, China

To identify circulating emerging/reemerging viral strains and epidemiological trends, an influenza sentinel surveillance network was established in Shandong Province, China, in 2005. Nasal and/or throat swabs from patients with influenza-like-illness were collected at sentinel hospitals. Influenza viruses were detected by reverse transcription polymerase chain reaction (RT-PCR) or virus isolation. From October 2005 to March 2012, 7763 (21.44 %) of 36,209 swab samples were positive for influenza viruses, including 5221 (67.25 %) influenza A and 2542 (32.75 %) influenza B. While the influenza viruses were detected year-round, their type/subtype distribution varied significantly. Peak influenza activity was observed from November to February. The proportion of laboratory-confirmed influenza cases was highest among participants aged 0-4 years (14.97 %) in the 2005-2009 and 2010-2012 influenza seasons and the positivity rate of influenza A(H1N1)pdm09 was highest in the 15 to 24 year age group during the 2009-2010 influenza season. Genetic analysis of hemagglutinin (HA) and neuraminidase (NA) genes revealed that the viruses matched seasonal influenza vaccine strains in general, with some amino acid mutations. Influenza A(H1N1)pdm09 strains isolated in Shandong Province were characterized by an S203T mutation that is specific to clade 7 isolates. This report illustrates that the Shandong Provincial influenza surveillance system was sensitive in detecting influenza virus variability by season and by genetic composition. This system will help official public health target interventions such as education programs and vaccines.

Antibody-Dependent Cell-Mediated Cytotoxicity to Hemagglutinin of Influenza A Viruses After Influenza Vaccination in Humans

Background.  Detection of neutralizing antibodies (nAbs) to influenza A virus hemagglutinin (HA) antigens by conventional serological assays is currently the main immune correlate of protection for influenza vaccines However, current prepandemic avian influenza vaccines are poorly immunogenic in inducing nAbs despite considerable protection conferred. Recent studies show that Ab-dependent cell-mediated cytotoxicity (ADCC) to HA antigens are readily detectable in the sera of healthy individuals and patients with influenza infection. Methods.  Virus neutralization and ADCC activities of serum samples from individuals who received either seasonal or a stock-piled H5N1 avian influenza vaccine were evaluated by hemagglutination inhibition assay, microneutralization assay, and an improved ADCC natural killer (NK) cell activation assay. Results.  Immunization with inactivated seasonal influenza vaccine led to strong expansion of both nAbs and ADCC-mediating antibodies (adccAbs) to H3 antigen of the vaccine virus in 24 postvaccination human sera. In sharp contrast, 18 individuals vaccinated with the adjuvanted H5N1 avian influenza vaccine mounted H5-specific antibodies with strong ADCC activities despite moderate virus neutralization capacity. Strength of HA-specific ADCC activities is largely associated with the titers of HA-binding antibodies and not with the fine antigenic specificity of anti-HA nAbs. Conclusions.  Detection of both nAbs and adccAbs may better reflect protective capacity of HA-specific antibodies induced by avian influenza vaccines.