Estimating effect of antiviral drug use during pandemic (H1N1) 2009 outbreak, United States

A framework for supporting health capability-based planning: Identifying and structuring health capabilities

The COVID-19 pandemic has highlighted that health security systems must be redesigned, in a way that they are better prepared and ready to cope with multiple and diverse health threats, from predictable and well-known epidemics to unexpected and challenging pandemics. A powerful way of accomplishing this goal is to focus the planning on health capabilities. This focus may enhance the ability to respond to and recover from health threats and emergencies, while helping to identify the level of resources required to maintain and build up those capabilities that are critical in ensuring the preparedness of health security systems. However, current attempts for defining and organizing health capabilities have some important limitations. First, such attempts were not designed to consider diverse scenarios and multiple health threats. Second, they provide a limited representation of capabilities and lack a systemic perspective. Third, they struggle to identify capability and resource gaps. In this article, we thus propose a new framework for identifying and structuring health capabilities and support health capability planning. The suggested framework has three main potential benefits. First, the framework may help policymakers in planning under high levels of uncertainty, by considering multiple realistic and stressful scenarios. Second, it can provide risk analysts with a more comprehensive representation of health capabilities and their complex relationships. Third, it can support planners in identifying resource and capability gaps. We illustrate the use of the framework in practice considering an outbreak scenario caused by three different health threats (COVID-19, Ebola, and Influenza viruses).

Wearable sensor-based detection of influenza in presymptomatic and asymptomatic individuals

BACKGROUND

The COVID-19 pandemic highlighted the need for early detection of viral infections in symptomatic and asymptomatic individuals to allow for timely clinical management and public health interventions.

METHODS

Twenty healthy adults were challenged with an influenza A (H3N2) virus and prospectively monitored from 7 days before through 10 days after inoculation, using wearable electrocardiogram and physical activity sensors (Clinical Trial: NCT04204493; https://clinicaltrials.gov/ct2/show/NCT04204993). This framework allowed for responses to be accurately referenced to the infection event. For each participant, we trained a semi-supervised multivariable anomaly detection model on data acquired before inoculation and used it to classify the post-inoculation dataset.

RESULTS

Inoculation with this challenge virus was well-tolerated with an infection rate of 85%. With the model classification threshold set so that no alarms were recorded in the 170 healthy days recorded, the algorithm correctly identified 16 of 17 (94%) positive presymptomatic and asymptomatic individuals, on average 58 hours post inoculation and 23 hrs before the symptom onset.

CONCLUSION

The data processing and modeling methodology show promise for the early detection of respiratory illness. The detection algorithm is compatible with data collected from smartwatches using optical techniques but needs to be validated in large heterogeneous cohorts in normal living conditions.

Diagnostic Accuracy of the Quidel Sofia Rapid Influenza Fluorescent Immunoassay in Patients with Influenza-like Illness: A Systematic Review and Meta-analysis

Background

Although the Quidel Sofia rapid influenza fluorescent immunoassay (FIA) is widely used to identify influenza A and B, the diagnostic accuracy of this test remains unclear. Thus, the objective of this study was to determine the diagnostic performance of this test compared to reverse transcriptase-polymerase chain reaction.

Methods

A systematic literature search was performed using MEDLINE, EMBASE, and the Cochrane Central Register. Pooled sensitivity, specificity, diagnostic odds ratio (DOR), and a hierarchical summary receiver-operating characteristic curve (HSROC) of this test for identifying influenza A and B were determined using meta-analysis. A sensitivity subgroup analysis was performed to identify potential sources of heterogeneity within selected studies.

Results

We identified 17 studies involving 8,334 patients. Pooled sensitivity, specificity, and DOR of the Quidel Sofia rapid influenza FIA for identifying influenza A were 0.78 (95% confidence interval [CI], 0.71–0.83), 0.99 (95% CI, 0.98–0.99), and 251.26 (95% CI, 139.39–452.89), respectively. Pooled sensitivity, specificity, and DOR of this test for identifying influenza B were 0.72 (95% CI, 0.60–0.82), 0.98 (95% CI, 0.96–0.99), and 140.20 (95% CI, 55.92–351.54), respectively. The area under the HSROC for this test for identifying influenza A was similar to that for identifying influenza B. Age was considered a probable source of heterogeneity.

Conclusion

Pooled sensitivities of the Quidel Sofia rapid influenza FIA for identifying influenza A and B did not quite meet the target level (≥80%). Thus, caution is needed when interpreting data of this study due to substantial between-study heterogeneity.

Seasonal influenza prevention and control in Taiwan-Strategies revisited

Influenza remains a serious public health threat in Taiwan. During 2017-18, Taiwan experienced two seasonal influenza epidemics caused by A/H3N2 and B, respectively. In addition to national influenza vaccination campaign, Taiwan Centers for Diseases Control and Infectious Disease Control Advisory Committee has multi-faceted strategies for seasonal influenza prevention and control to mitigate the risk of disease transmission among vulnerable groups and decrease influenza-related morbidity and mortality. In this article, we reviewed the key elements of the prevention and control strategies-enhanced influenza surveillance, antiviral drugs stockpile and management, critical care and medical resources reallocation, public risk communication and infection control measures. Given the complexity and challenging nature of controlling seasonal influenza epidemics, collaboration between health professionals is crucial to optimize the health of Taiwanese people.

Timely Antiviral Administration During an Influenza Pandemic: Key Components

Prompt treatment of ill persons with influenza antivirals will be an important part of a future pandemic influenza response. This essay reviews key lessons learned from the 2009 H1N1 pandemic and the changing landscape of antiviral drug availability, and identifies and describes the multiple components needed to ensure the timely administration of antiviral drugs during a future pandemic. Fortunately, many of these planning efforts can take place before a pandemic strikes to improve outcomes during a future public health emergency.

Influenza in Asthmatics: For Better or for Worse?

Asthma and influenza are two pathologic conditions of the respiratory tract that affect millions worldwide. Influenza virus of the 2009 pandemic was highly transmissible and caused severe respiratory disease in young and middle-aged individuals. Asthma was discovered to be an underlying co-morbidity that led to hospitalizations during this influenza pandemic albeit with less severe outcomes. However, animal studies that investigated the relationship between allergic inflammation and pandemic (p)H1N1 infection, showed that while characteristics of allergic airways disease were exacerbated by this virus, governing immune responses that cause exacerbations may actually protect the host from severe outcomes associated with influenza. To better understand the relationship between asthma and severe influenza during the last pandemic, we conducted a systematic literature review of reports on hospitalized patients with asthma as a co-morbid condition during the pH1N1 season. Herein, we report that numerous other underlying conditions, such as cardiovascular, neurologic, and metabolic diseases may have been underplayed as major drivers of severe influenza during the 2009 pandemic. This review synopses, (1) asthma and influenza independently, (2) epidemiologic data surrounding asthma during the 2009 influenza pandemic, and (3) recent advances in our understanding of allergic host–pathogen interactions in the context of allergic airways disease and influenza in mouse models. Our goal is to showcase possible immunological benefits of allergic airways inflammation as countermeasures for influenza virus infections as a learning tool to discover novel pathways that can enhance our ability to hinder influenza virus replication and host pathology induced thereof.

Synergistic effects of influenza and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) can be eliminated by the use of influenza therapeutics: experimental evidence for the multi-hit hypothesis

Central Nervous System inflammation has been implicated in neurodegenerative disorders including Parkinson’s disease (Ransohoff, Science 353: 777–783, 2016; Kannarkat et al. J. Parkinsons Dis. 3: 493–514, 2013). Here, we examined if the H1N1 influenza virus (Studahl et al. Drugs 73: 131–158, 2013) could synergize with the parkinsonian toxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (Jackson-Lewis et al. in Mark LeDoux (ed) Movement Disorders: Genetics and Models: 287–306, Elsevier, 2015) to induce a greater microglial activation and loss of substantia nigra pars compacta dopaminergic neurons than either insult alone. H1N1-infected animals administered 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine exhibit a 20% greater loss of substantia nigra pars compacta dopaminergic neurons than occurs from the additive effects of H1N1 or 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine alone (p < 0.001). No synergistic effects were found in microglial activation. The synergistic dopaminergic neuron loss is eliminated by influenza vaccination or treatment with oseltamivir carboxylate. This work shows that multiple insults can induce synergistic effects; and even these small changes can be significant as it might allow one to cross a phenotypic disease threshold that would not occur from individual non-interacting exposures. Our observations also have important implications for public health, providing impetus for influenza vaccination or prompt treatment with anti-viral medications upon influenza diagnosis.

Influenza Antiviral Expenditures and Outpatient Prescriptions in the United States, 2003-2012

STUDY OBJECTIVES

The clinical efficacy and cost-effectiveness of influenza antiviral use are controversial, with recent analyses suggesting potentially limited value. Thus, the objectives of this study were to describe influenza antiviral expenditures overall and by health care setting over a 10-year period (2003-2012) and to assess the correlation between outpatient influenza antiviral prescription use and influenza-like illness (ILI) outpatient visits.

DESIGN

Retrospective, cross-sectional study.

DATA SOURCES

IMS Health National Sales Perspectives and Xponent databases and Centers for Disease Control and Prevention ILINet national influenza surveillance system database.

PATIENTS

All prescriptions for oseltamivir, rimantadine, or zanamivir from community pharmacies, mail order pharmacies, clinics, nonfederal hospitals, and other health care settings (federal hospitals, military facilities, jails and prisons, universities, staff-model health maintenance organizations, veterinary hospitals and clinics, and long-term care facilities) between January 1, 2003, and December 31, 2012.

MEASUREMENTS AND MAIN RESULTS

Prescribing rates were calculated (prescriptions/1000 persons) for each year from 2003 to 2012 by using U.S. Census Bureau data. Influenza season was defined as July 1-June 30 of each calendar year. Linear regression assessed the correlation between influenza antiviral expenditures, prescription use, and ILI diagnoses. From 2003 to 2012, influenza antiviral drug expenditures accounted for $3.74 billion, with the majority from community pharmacies. After adjusting for inflation, no growth was observed for expenditures. A total of 32.8 million influenza antiviral prescriptions were dispensed from community pharmacies during the study period, and these prescriptions experienced 133.2% growth from 2003 to 2012. One third of expenditures and one quarter of dispensed prescriptions were in 2009. Influenza seasons were correlated with ILI and antiviral prescriptions. Annual community pharmacy expenditures were also associated with influenza antiviral prescriptions dispensed over the 10-year period.

CONCLUSION

Influenza antivirals totaled $3.74 billion in the United States from 2003 to 2012, with the majority in 2009 and from community pharmacies. Influenza antivirals constituted a small proportion of total medication expenditures, but unforeseen pandemics resulted in unusually high use and expenditures. Influenza antiviral prescriptions dispensed from community pharmacies were associated with ILI and drug expenditures.

CDC's Evolving Approach to Emergency Response

The Centers for Disease Control and Prevention (CDC) transformed its approach to preparing for and responding to public health emergencies following the anthrax attacks of 2001. The Office of Public Health Preparedness and Response, an organizational home for emergency response at CDC, was established, and 4 programs were created or greatly expanded after the anthrax attacks: (1) an emergency management program, including an Emergency Operations Center; (2) increased support of state and local health department efforts to prepare for emergencies; (3) a greatly enlarged Strategic National Stockpile of medicines, vaccines, and medical equipment; and (4) a regulatory program to assure that work done on the most dangerous pathogens and toxins is done as safely and securely as possible. Following these changes, CDC led responses to 3 major public health emergencies: the 2009-10 H1N1 influenza pandemic, the 2014-16 Ebola epidemic in West Africa, and the ongoing Zika epidemic. This article reviews the programs of CDC's Office of Public Health Preparedness, the major responses, and how these responses have resulted in changes in CDC's approach to responding to public health emergencies.

Discovering Multi-Scale Co-Occurrence Patterns of Asthma and Influenza with Oak Ridge Bio-Surveillance Toolkit

We describe a data-driven unsupervised machine learning approach to extract geo-temporal co-occurrence patterns of asthma and the flu from large-scale electronic healthcare reimbursement claims (eHRC) datasets. Specifically, we examine the eHRC data from 2009 to 2010 pandemic H1N1 influenza season and analyze whether different geographic regions within the United States (US) showed an increase in co-occurrence patterns of the flu and asthma. Our analyses reveal that the temporal patterns extracted from the eHRC data show a distinct lag time between the peak incidence of the asthma and the flu. While the increased occurrence of asthma contributed to increased flu incidence during the pandemic, this co-occurrence is predominant for female patients. The geo-temporal patterns reveal that the co-occurrence of the flu and asthma are typically concentrated within the south-east US. Further, in agreement with previous studies, large urban areas (such as New York, Miami, and Los Angeles) exhibit co-occurrence patterns that suggest a peak incidence of asthma and flu significantly early in the spring and winter seasons. Together, our data-analytic approach, integrated within the Oak Ridge Bio-surveillance Toolkit platform, demonstrates how eHRC data can provide novel insights into co-occurring disease patterns.

Estimating the United States demand for influenza antivirals and the effect on severe influenza disease during a potential pandemic

Following the detection of a novel influenza strain A(H7N9), we modeled the use of antiviral treatment in the United States to mitigate severe disease across a range of hypothetical pandemic scenarios. Our outcomes were total demand for antiviral (neuraminidase inhibitor) treatment and the number of hospitalizations and deaths averted. The model included estimates of attack rate, healthcare-seeking behavior, prescription rates, adherence, disease severity, and the potential effect of antivirals on the risks of hospitalization and death. Based on these inputs, the total antiviral regimens estimated to be available in the United States (as of April 2013) were sufficient to meet treatment needs for the scenarios considered. However, distribution logistics were not examined and should be addressed in future work. Treatment was estimated to avert many severe outcomes (5200-248,000 deaths; 4800-504,000 hospitalizations); however, large numbers remained (25,000-425,000 deaths; 580,000-3,700,000 hospitalizations), suggesting that the impact of combinations of interventions should be examined.

Neuraminidase inhibitor therapy in a military population

BACKGROUND

Although neuraminidase inhibitors (NI) are the mainstay of treatment for influenza infection, prescribing practice for these agents is not well described. Additionally, benefit is contested.

OBJECTIVES

We examined provider prescriptions of NI during the 2009 pandemic and post-pandemic periods. We also evaluated the effectiveness of NI in reducing severity of influenza infection.

STUDY DESIGN

Data on NI prescription and severity of influenza infection were compiled in healthy pediatric and adult beneficiaries enrolled in a prospective study of influenza like illness conducted at five military medical centers over five years. Subjects underwent nasal swabs to determine viral etiology of their infection. Demographic, medication and severity data were collected. Subjects with positive influenza were included.

RESULTS

Two hundred sixty three subjects were influenza positive [38% [H1N1] pdm09, 38.4% H3N2, and 20.5% B); 23.9% were treated with NI. NI were initiated within 48h in 63% of treated subjects. Although NI use increased over the five years of the study, early use declined. Most measures for severity of illness were not significantly reduced with NI; adults treated within 48h had only a modest reduction in duration and severity of some of their symptoms.

CONCLUSIONS

NI use in our population is increasing, but early use is not. NI use resulted in no reduction in complications of illness. Resolution of symptoms and reduction in severity of some symptoms were slightly better in adults who were treated early. These modest benefits do not support routine treatment with NI in otherwise healthy individuals with influenza.

Optimizing distribution of pandemic influenza antiviral drugs

We provide a data-driven method for optimizing pharmacy-based distribution of antiviral drugs during an influenza pandemic in terms of overall access for a target population and apply it to the state of Texas, USA. We found that during the 2009 influenza pandemic, the Texas Department of State Health Services achieved an estimated statewide access of 88% (proportion of population willing to travel to the nearest dispensing point). However, access reached only 34.5% of US postal code (ZIP code) areas containing <1,000 underinsured persons. Optimized distribution networks increased expected access to 91% overall and 60% in hard-to-reach regions, and 2 or 3 major pharmacy chains achieved near maximal coverage in well-populated areas. Independent pharmacies were essential for reaching ZIP code areas containing <1,000 underinsured persons. This model was developed during a collaboration between academic researchers and public health officials and is available as a decision support tool for Texas Department of State Health Services at a Web-based interface.

Antiviral medication use in a cohort of pregnant women during the 2009-2010 influenza pandemic

Preventing influenza-like illness (ILI) during pregnancy with antiviral medication use (AVMU) can mitigate serious health risks to mother and foetus. We report on AVMU in pregnant women in Ontario, Canada, and describe characteristics of AVMU during the 2009-2010 H1N1 pandemic. Rates and risk estimates of AVMU were compared across multiple categories and stratified across ILI infection status. Increased AVMU was observed in women with influenza infections, active smokers, those vaccinated against influenza, and those with pre-existing co-morbidities. Decreased AVMU was observed in women with multiple gestations, and those in neighbourhoods of high immigrant concentrations. Our stratified analysis indicated that the observed patterns differed by ILI infection status. We demonstrated that once infected, women across multiple groups were equally likely to use antiviral medications. In this report we also propose possible clinical explanations for the observed differences in AVMU, which will be useful in planning prevention initiatives for future pandemics.

Assessing the use of antiviral treatment to control influenza

Vaccines are the cornerstone of influenza control policy, but can suffer from several drawbacks. Seasonal influenza vaccines are prone to production problems and low efficacies, while pandemic vaccines are unlikely to be available in time to slow a rapidly spreading global outbreak. Antiviral therapy was found to be beneficial during the influenza A(H1N1)pdm09 pandemic even with limited use; however, antiviral use has decreased further since then. We sought to determine the role antiviral therapy can play in pandemic and seasonal influenza control using conservative estimates of antiviral efficacy, and to assess if conservative but targeted strategies could be employed to optimize the use of antivirals. Using an age-structured contact network model for an urban population, we compared the transmission-blocking ability of a conservative antiviral therapy strategy to the susceptibility-reducing effects of a robust influenza vaccine. Our results show that while antiviral therapy cannot replace a robust influenza vaccine, it can play a role in reducing attack rates and eliminating outbreaks, and could significantly reduce public health burden when vaccine is either unavailable or ineffective. We also found that antiviral therapy, by treating those who are infected, is naturally a highly optimized strategy, and need not be improved upon with expensive targeted campaigns.

Effectiveness of neuraminidase inhibitors in reducing mortality in patients admitted to hospital with influenza A H1N1pdm09 virus infection: a meta-analysis of individual participant data

BACKGROUND

Neuraminidase inhibitors were widely used during the 2009-10 influenza A H1N1 pandemic, but evidence for their effectiveness in reducing mortality is uncertain. We did a meta-analysis of individual participant data to investigate the association between use of neuraminidase inhibitors and mortality in patients admitted to hospital with pandemic influenza A H1N1pdm09 virus infection.

METHODS

We assembled data for patients (all ages) admitted to hospital worldwide with laboratory confirmed or clinically diagnosed pandemic influenza A H1N1pdm09 virus infection. We identified potential data contributors from an earlier systematic review of reported studies addressing the same research question. In our systematic review, eligible studies were done between March 1, 2009 (Mexico), or April 1, 2009 (rest of the world), until the WHO declaration of the end of the pandemic (Aug 10, 2010); however, we continued to receive data up to March 14, 2011, from ongoing studies. We did a meta-analysis of individual participant data to assess the association between neuraminidase inhibitor treatment and mortality (primary outcome), adjusting for both treatment propensity and potential confounders, using generalised linear mixed modelling. We assessed the association with time to treatment using time-dependent Cox regression shared frailty modelling.

FINDINGS

We included data for 29,234 patients from 78 studies of patients admitted to hospital between Jan 2, 2009, and March 14, 2011. Compared with no treatment, neuraminidase inhibitor treatment (irrespective of timing) was associated with a reduction in mortality risk (adjusted odds ratio [OR] 0·81; 95% CI 0·70-0·93; p=0·0024). Compared with later treatment, early treatment (within 2 days of symptom onset) was associated with a reduction in mortality risk (adjusted OR 0·48; 95% CI 0·41-0·56; p<0·0001). Early treatment versus no treatment was also associated with a reduction in mortality (adjusted OR 0·50; 95% CI 0·37-0·67; p<0·0001). These associations with reduced mortality risk were less pronounced and not significant in children. There was an increase in the mortality hazard rate with each day's delay in initiation of treatment up to day 5 as compared with treatment initiated within 2 days of symptom onset (adjusted hazard ratio [HR 1·23] [95% CI 1·18-1·28]; p<0·0001 for the increasing HR with each day's delay).

INTERPRETATION

We advocate early instigation of neuraminidase inhibitor treatment in adults admitted to hospital with suspected or proven influenza infection.

FUNDING

F Hoffmann-La Roche.

Impact of medical and behavioural factors on influenza-like illness, healthcare-seeking, and antiviral treatment during the 2009 H1N1 pandemic: USA, 2009-2010

We analysed a cross-sectional telephone survey of U.S. adults to assess the impact of selected characteristics on healthcare-seeking behaviours and treatment practices of people with influenza-like illness (ILI) from September 2009 to March 2010. Of 216,431 respondents, 8.1% reported ILI. After adjusting for selected characteristics, respondents aged 18-64 years with the following factors were more likely to report ILI: a diagnosis of asthma [adjusted odds ratio (aOR) 1.88, 95% CI 1.67-2.13] or heart disease (aOR 1.41, 95% CI 1.17-1.70), being disabled (aOR 1.75, 95% CI 1.57-1.96), and reporting financial barriers to healthcare access (aOR 1.63, 95% CI 1.45-1.82). Similar associations were seen in respondents aged ≥ 65 years. Forty percent of respondents with ILI sought healthcare, and 14% who sought healthcare reported receiving influenza antiviral treatment. Treatment was not more frequent in patients with high-risk conditions, except those aged 18-64 years with heart disease (aOR 1.90, 95% CI 1.03-3.51). Of patients at high risk for influenza complications, self-reported ILI was greater but receipt of antiviral treatment was not, despite guidelines recommending their use in this population.

Outpatient influenza antiviral prescription trends with influenza-like illness in the USA, 2008-2010

The 2009 novel H1N1 influenza A virus (H1N1) became a global pandemic. Data on antiviral prescriptions by location from 2008 to 2010 have not been reported. The purpose of this study was to assess antiviral geographic trends and correlation with influenza-like illness (ILI) over 3 years. Percent of outpatient ILI visits and antiviral prescriptions from 1 January 2008 to 31 December 2010 were included. Linear regression was used to assess correlation. In total, 14 million antivirals were dispensed during this period. A 115% increase was observed in 2009 compared with prescriptions dispensed in 2008, and an 84% decrease was observed in 2010 compared with 2009. The rate of antivirals was 1.32 prescriptions/100 persons in 2008, 2.85/100 persons in 2009 and 0.435/100 persons in 2010. 2009 regional growth was observed in most states and was highest in the West (293%) and the Northeast (272%). A positive correlation was observed between antivirals and ILI visits (R(2)=0.7853; P<0.0001). With the 2009 H1N1 pandemic, antivirals increased compared with 2008 or 2010. Without the concern of H1N1, antivirals decreased in 2010 to levels lower than 2008. Geographic trends were also observed, which may be a result of the different intensity of influenza transmission and difference practice patterns. ILI diagnoses correlate with influenza antiviral prescription use in the USA.

Early therapy with neuraminidase inhibitors for influenza A (H1N1) pdm 2009 infection

BACKGROUND

Neuraminidase inhibitors have been reported to decrease mortality in patients infected with influenza A (H1N1) pdm 2009 (H1N1 pdm09), but it is not clear whether they are effective against H1N1pdm09 in apparently healthy children.

METHODS

The effect of early treatment with neuraminidase inhibitors on 70 otherwise healthy children with possible H1N1 pdm09 (pH1N1pdm09) infection was investigated. The children were simultaneously treated with a neuraminidase inhibitor (oseltamivir or zanamivir) and maoto, a Japanese traditional herbal medicine, which had been reported to be effective against seasonal influenza. Clinical severity was assessed using patient history, namely the worst values for clinical vital signs and laboratory data on admission. After refining these parameters with univariate, decision tree and multiple regression analysis, mean covariance structure equation analysis was used to investigate the association of estimated clinical severity to the selected parameters.

RESULTS

Total path analysis using a Bayesian method indicated that the estimated clinical severity of pH1N1pdm09 was positively associated with maximum body temperature, pulse rate, respiration rate, duration necessary for defervescence, admission duration and log urinary β2-microglobulin/creatinine level, and negatively associated with age and the presence and duration of treatment with the neuraminidase inhibitor in the outpatient clinic.

CONCLUSIONS

This study provides the first clinical evidence that early treatment with neuraminidase inhibitors in outpatient clinic decreased the estimated clinical severity of pH1N1pdm09 in apparently otherwise healthy pediatric inpatients.

Influenza infection in infants aged <6 months during the H1N1-09 pandemic: a hospital-based case series

AIMS

To document risk factors, clinical features and outcomes in infants <6 months old admitted with laboratory-confirmed influenza to The Children's Hospital at Westmead during the H1N1-09 pandemic.

METHODS

Prospective, hospital-based case series of infants admitted June-September 2009, identified by the Paediatric Active Enhanced Disease Surveillance system and supplemented by telephone interview post-discharge.

RESULTS

Thirty-two infants <6 months old had influenza A: 18 H1N1-09, 11 H3N2 and three unknown subtypes. After discharge, 28 (88%) families were telephoned and provided additional information. Documented risk factors included close contact with young children (46%), living with a smoker (36%), intensive or special care at birth (25%), pre-existing illness (16%) and preterm birth (14%). The number of persons per household was double the state average. Only 14% of mothers were vaccinated against seasonal influenza. Infants commonly presented with cough (69%), coryza (69%), lethargy (38%), fever (31%), dyspnoea (31%) and vomiting (28%). Complications included pneumonia (22%), and bacterial (9%) and viral (6%) co-infection. Five infants (15%) required admission to intensive care, and one was mechanically ventilated. Sixteen (57%) had ongoing respiratory problems, and six (21%) presented to the Emergency Department within 6 months of discharge.

CONCLUSIONS

These novel data are clinically important. Rates of influenza in infants may be reduced by vaccinating close contacts and minimising exposure to infected contacts and cigarette smoke.

Oseltamivir use and outcomes during the 2009 influenza A H1N1 pandemic in Taiwan

Background

The Taiwan CDC provided free oseltamivir to all patients with influenza infections confirmed by rapid testing or who had clinical warning symptoms during the 2009 H1N1 influenza pandemic in Taiwan. However, oseltamivir utilization patterns, cost, and outcomes among oseltamivir-treated patients remained unclear.

Method

A population-level, observational cohort study was conducted using the Taiwan National Health Insurance Database from January to December 2009 to describe the use of oseltamivir.

Result

Prescription trend over weeks increased after a change in government policy and responded to the influenza virus activity. The overall prescription rate was 22.33 per 1000 persons, with the highest prescription rate of 116.5 for those aged 7–12 years, followed by 69.0 for those aged 13–18 years, while the lowest rate was 1.7 for those aged ≥ 65 years. As influenza virus activity increased, the number of prescriptions for those aged ≤18 years rose significantly, whereas no substantial change was observed for those aged ≥65 years. There were also regional variations in terms of oseltamivir utilization and influenza complication rates.

Conclusions

Oseltamivir was widely used in the 2009 H1N1 influenza pandemic in Taiwan, particularly in those aged 7–18 years. The number of prescriptions for oseltamivir increased with a change in government policy and with increasing cases of pandemic influenza. Further study is needed to examine whether there is an over- or under-use of anti-influenza drugs in different age groups or regions and to examine the current policy of public use of anti-influenza drugs to reduce influenza-associated morbidity and mortality.

Neuraminidase inhibitors for influenza: a review and public health perspective in the aftermath of the 2009 pandemic

OBJECTIVES

The objectives of this study were to: (1) reflect on key stages in the discovery, development and pre-pandemic use of neuraminidase inhibitors (NAIs), (2) summarise the evidence of NAI effectiveness for treatment and prophylaxis of seasonal influenza prior to the 2009 pandemic, and (3) summarise the evidence base generated during the 2009 pandemic period.

DESIGN

A rapid systematic review of evidence published to June 2010 was conducted where existing high-quality systematic reviews formed a baseline and were supplemented with data from other reviews, randomised controlled trials (RCTs) and observational studies.

MAIN OUTCOME MEASURES

Severity and duration of symptoms; rates of severe illness, complications and death following treatment for influenza or influenza-like illness; rates of influenza and influenza-like illness following long-term prophylaxis or post-exposure prophylaxis of household contacts.

RESULTS

Prior to the 2009 pandemic, evidence from RCTs conducted in seasonal influenza epidemics indicated that NAIs used to treat laboratory-confirmed influenza in healthy adults reduced the duration of illness by one day. NAIs provide high levels of protective efficacy in adults when given long-term or in household-based post-exposure prophylaxis for seasonal influenza. Several 2009 pandemic period observational studies suggest that early treatment may reduce rates of hospitalisation and in-hospital mortality, but data from that period do not substantially increase the evidence base on prophylaxis, although they confirm effectiveness.

CONCLUSIONS

NAIs should be deployed during a future pandemic for either post-exposure prophylaxis or treatment depending on national policy considerations and logistics. The existing evidence base on effectiveness against severe outcomes requires supplementation.

Impact of neuraminidase inhibitor treatment on outcomes of public health importance during the 2009-2010 influenza A(H1N1) pandemic: a systematic review and meta-analysis in hospitalized patients

BACKGROUND

The impact of neuraminidase inhibitor (NAI) treatment on clinical outcomes of public health importance during the 2009-2010 pandemic has not been firmly established.

METHODS

We conducted a systematic review and meta-analysis, searching 11 databases (2009 through April 2012) for relevant studies. We used standard methods conforming to Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using random effects models.

RESULTS

Regarding mortality we observed a nonsignificant reduction associated with NAI treatment (at any time) versus none (OR, 0.72 [95% CI, .51-1.01]). However we observed significant reductions for early treatment (≤48 hours after symptom onset) versus late (OR, 0.38 [95% CI, .27-.53]) and for early treatment versus none (OR, 0.35 [95% CI, .18-.71]). NAI treatment (at any time) versus none was associated with an elevated risk of severe outcome (OR, 1.76 [95% CI, 1.22-2.54]), but early versus late treatment reduced the likelihood (OR, 0.41 [95% CI, .30-.56]).

CONCLUSIONS

During the 2009-2010 influenza A(H1N1) pandemic, early initiation of NAI treatment reduced the likelihood of severe outcomes compared with late or no treatment.

PROSPERO REGISTRATION

CRD42011001273.

Public health management of antiviral drugs during the 2009 H1N1 influenza pandemic: a survey of local health departments in California

BACKGROUND

The large-scale deployment of antiviral drugs from the Strategic National Stockpile during the 2009 H1N1 influenza response provides a unique opportunity to study local public health implementation of the medical countermeasure dispensing capability in a prolonged event of national significance. This study aims to describe the range of methods used by local health departments (LHDs) in California to manage antiviral activities and to gain a better understanding of the related challenges experienced by health departments and their community partners.

METHODS

This research employed a mixed-methods approach. First, a multi-disciplinary focus group of pandemic influenza planners from key stakeholder groups in California was convened in order to generate ideas and identify critical themes related to the local implementation of antiviral activities during the H1N1 influenza response. These qualitative data informed the development of a web-based survey, which was distributed to all 61 LHDs in California for the purpose of assessing the experiences of a representative sample of local health agencies in a large region.

RESULTS

Forty-four LHDs participated in this study, representing 72% of the local public health agencies in California. While most communities dispensed a modest number of publicly purchased antivirals, LHDs nevertheless drew on their previous work and engaged in a number of antiviral activities, including: acquiring, allocating, distributing, dispensing, tracking, developing guidance, and communicating to the public and clinical community. LHDs also identified specific antiviral challenges presented by the H1N1 pandemic, including: reconciling multiple sources and versions of antiviral guidance, determining appropriate uses and recipients of publicly purchased antivirals, and staffing shortages.

CONCLUSIONS

The 2009 H1N1 influenza pandemic presented an unusual opportunity to learn about the role of local public health in the management of antiviral response activities during a real public health emergency. Results of this study offer an important descriptive account of LHD management of publicly purchased antivirals, and provide practitioners, policy makers, and academics with a practice-based assessment of these events. The issues raised and the challenges faced by LHDs should be leveraged to inform public health planning for future pandemics and other emergency events that require medical countermeasure dispensing activities.