Severity Of Pandemic Influenza Research Articles

The Application of Indicators to Assess the Severity of Seasonal Influenza Epidemics in Democratic Republic of Congo, 2015 to 2019

Introduction: Among the lessons learned from the 2009 influenza pandemic was the lack of a robust, standardized method that would allow a timely assessment of the severity of pandemic influenza. To remedy this deficiency, WHO has set up an evaluation tool based on the following indicators: 1) transmissibility, 2) seriousness of disease, and 3) impact of the influenza pandemic. By using this pandemic influenza severity assessment (PISA) tool, this study aimed to evaluate the severity of DRC influenza seasons between 2015 and 2019 to better prepare the country against the possible occurrence of an influenza pandemic. Methods: We performed a secondary data analysis from the DRC Influenza routine surveillance. We only explored the transmissibility among PISA indicators. Results: The results of our study showed that the DRC influenza seasons had two waves. The first went from the 40th week to the 10th week, with a peak at the 50th week, and the second wave ran from the 15th week to the 40th, with a peak at the 19th week. There was an inter-wave period between the 10th and 15th weeks. Of all the studied seasons, 42.8% were characterized by low intensity, 33.3% by moderate intensity, 19.0% by high intensity, and 4.8% by extraordinary intensity. Conclusion: The use of the PISA transmissibility indicator has contributed to better understanding influenza seasons in the Democratic Republic of Congo.

Ethnic variation in risk genotypes based on single nucleotide polymorphisms (SNPs) of the interferon-inducible transmembrane 3 (IFITM3) gene, a susceptibility factor for pandemic 2009 H1N1 influenza A virus.

The interferon-inducible transmembrane 3 (IFITM3) protein is an effector of the host innate immune system that shows defensive activity against a wide range of viruses, including the influenza A virus. Previous studies have reported that three transcription-related regulatory single nucleotide polymorphisms (SNPs), rs12252, rs34481144, and rs6598045, showed potent associations with the severity of pandemic influenza A 2009 infection and susceptibility to this virus, respectively. However, the distribution of the risk genotypes of these three SNPs according to ethnic background has remained elusive. In this study, we compared the genotype and allele frequencies of the IFITM3 polymorphisms among several ethnic groups including American, African, European, South Asian, and East Asian using chi-square test. In addition, we analyzed the worldwide distribution of risk genotypes for pandemic influenza A 2009 virus infection. We found that the genotype and allele distributions of the rs12252, rs34481144, and rs6598045 SNPs were significantly different among several ethnic groups. In addition, the risk genotypes of the IFITM3 polymorphisms were also significantly different worldwide. To the best of our knowledge, this was the first simultaneous estimation of the risk genotypes of the IFITM3 gene with respect to pandemic influenza A 2009 virus infection.

Increasing the intent to receive a pandemic influenza vaccination: Testing the impact of theory-based messages

ObjectiveVaccination is an effective preventive measure to reduce influenza transmission, especially important in a pandemic. Despite the messages encouraging vaccination during the last pandemic, uptake remained low (37.6% in clinical risk groups). This study investigated the effect of different types of messages regarding length, content type, and framing on vaccination intention. MethodAn online experiment was conducted in February 2015. A representative sample of 1424 people living in England read a mock newspaper article about a novel influenza pandemic before being randomised to one of four conditions: standard Department of Health (DoH) (long message) and three brief theory-based messages - an abridged version of the standard DoH and two messages additionally targeting pandemic influenza severity and vaccination benefits (framed as risk-reducing or health-enhancing, respectively). Intention to be vaccinated and potential mediators were measured. ResultsThe shortened DoH message increased vaccination intention more than the longer one, by increasing perceived susceptibility, anticipated regret and perceived message personal relevance while lowering perceived costs, despite the longer one being rated as slightly more credible. Intention to be vaccinated was not improved by adding information on severity and benefits, and the health-enhancing message was not more effective than the risk-reducing. ConclusionA briefer message resulted in greater intention to be vaccinated, whereas emphasising the severity of pandemic influenza and the benefits of vaccination did not. Future campaigns should consider using brief theoretically-based messages, targeting knowledge about influenza and precautionary measures, perceived susceptibility to pandemic influenza, and the perceived efficacy and reduced costs of vaccination.

Influenza and Pneumococcal Immunization

Influenza and Pneumococcal Immunization

Toward unbiased assessment of treatment and prevention: modeling household transmission of pandemic influenza

Providing valid and reliable estimates of the transmissibility and severity of pandemic influenza in real time is key to guide public health policymaking. In particular, early estimates of the transmissibility are indispensable for determining the type and intensity of interventions. A recent study by House and colleagues in BMC Medicine devised a stochastic transmission model to estimate the unbiased risk of transmission within households, applying the method to datasets of the 2009 A/H1N1 influenza pandemic. Here, we discuss future challenges in household transmission studies and underscore the need to systematically collect epidemiological data to decipher the household transmission dynamics. We emphasize the need to consider three critical issues for future improvements: (i) capturing age-dependent heterogeneity within households calls for intensive modeling efforts, (ii) the timeline of observation during the course of an epidemic and the length of follow-up should be aligned with study objectives, and (iii) the use of laboratory methods, especially molecular techniques, is encouraged to distinguish household transmissions from those arising in the community.See related article: http://www.biomedcentral.com/1741-7015/10/117

Likely effectiveness of pharmaceutical and non-pharmaceutical interventions for mitigating influenza virus transmission in Mongolia

To assess the likely benefit of the interventions under consideration for use in Mongolia during future influenza pandemics. A stochastic, compartmental patch model of susceptibility, exposure, infection and recovery was constructed to capture the key effects of several interventions--travel restrictions, school closure, generalized social distancing, quarantining of close contacts, treatment of cases with antivirals and prophylaxis of contacts--on the dynamics of influenza epidemics. The likely benefit and optimal timing and duration of each of these interventions were assessed using Latin-hypercube sampling techniques, averaging across many possible transmission and social mixing parameters. Timely interventions could substantially alter the time-course and reduce the severity of pandemic influenza in Mongolia. In a moderate pandemic scenario, early social distancing measures decreased the mean attack rate from around 10% to 7-8%. Similarly, in a severe pandemic scenario such measures cut the mean attack rate from approximately 23% to 21%. In both moderate and severe pandemic scenarios, a suite of non-pharmaceutical interventions proved as effective as the targeted use of antivirals. Targeted antiviral campaigns generally appeared more effective in severe pandemic scenarios than in moderate pandemic scenarios. A mathematical model of pandemic influenza transmission in Mongolia indicated that, to be successful, interventions to prevent transmission must be triggered when the first cases are detected in border regions. If social distancing measures are introduced at this stage and implemented over several weeks, they may have a notable mitigating impact. In low-income regions such as Mongolia, social distancing may be more effective than the large-scale use of antivirals.

Estimating and comparing case fatality rates of pandemic influenza A (H1N1) 2009 in its early stage in different countries

AimThe case fatality rate (CFR) of the novel influenza A (H1N1) 2009 was estimated to gain an understanding of the virulence at the early stage of the pandemic, and it was interpreted and reported primarily as a point estimate without an accompanying measure of precision. To allow proper interpretation of the estimated CFR, the uncertainty inherited from the data sample should be reflected in an inferential conclusion. The aim of this article is to construct confidence limits around the estimates from the sample and then compare the CFR of pandemic influenza A (H1N1) 2009 in its early stage to that in different areas.MethodsData were extracted from published papers and WHO pandemic surveillance reports. Statistical method such as the bootstrap approach is used to obtain estimates of confidence intervals.ResultsThe estimates of CFR and their confidence intervals in the initial stage of the pandemic are provided for 28 countries (or areas) in this article. The comparison of CFR for 28 countries (or areas) is shown and it is found that the pandemic in South American countries such as Argentina, Uruguay, Costa Rica, Colombia, Paraguay, Dominican Republic, Jamaica, Puerto Rico, were more severe than other countries which had reported cases to corresponding organizations. The analysis shows that the severity of the disease in the USA and Canada has no significant difference.ConclusionThe CFRs of pandemic influenza A (H1N1) 2009 for 28 countries (or areas) with an accompanying measure of precision are estimated. Therefore, it is possible to compare the severity of pandemic influenza between different countries and to know whether a difference between the severities is significant.

Clinical Characteristics of Pandemic Influenza A (H1N1) 2009 Pediatric Infection in Busan and Gyeongsangnam-do: One Institution

BackgroundThis study investigated the clinical characteristics and risk factors of the severity of pandemic influenza A (H1N1) 2009 infection in pediatric patients in Busan and Gyeongsangnam-do.MethodsCases of influenza A (H1N1) 2009 in patients under the age of 18 years, confirmed by reverse transcription polymerase chain reaction, at Pusan National University Hospital and Pusan National University Yangsan Hospital from the last week of August 2009 through the last week of February 2010 were retrospectively analyzed.ResultsOf the 3,777 confirmed cases of influenza A (H1N1) 2009, 2,200 (58.2%) were male and 1,577 (41.8%) were female. The average age of the patients was 8.4±4.8 years. The total cases peaked during 44th to 46th week. Most of the patients were in the 5- to 9-year-old age group. Oseltamivir was administered to 2,959 (78.3%) of the patients. 221 patients (5.9%) were hospitalized, age an average of 6.7±4.5 years. The average duration of hospitalization was 7.4±5.6 days. One hundred cases (45.2%) had pneumonia. Risk factors for hospitalization included male gender, <2 years of age, and underlying disease. Children with asthma were at very high risk of hospitalization, over 20 times the non-asthmatic children (odds ratio [OR], 21.684; confidence interval [CI], 13.295~39.791). Likewise the children with neurologic deficits faced a 16 times higher risk (OR, 15.738; CI, 7.961~31.111). Ten of the patients (4.5%) were admitted to the intensive care unit, and eight (3.6%) required mechanical ventilation.ConclusionOf the pediatric patients with pandemic influenza A (H1N1) 2009, most of the patients were in the 5- to 9-year-old age group. Risk factors for hospitalization included male gender, <2 years of age, and underlying disease. The most common complication was pneumonia. The very high risk of severe morbidity in children with asthma or neurologic disease shows the critical importance of targeted vaccine coverage, special awareness and swift care by both guardians and primary care providers.

Excess mortality from seasonal influenza is negligible below the age of 50 in Israel: implications for vaccine policy

PurposeEvaluation of the severity of pandemic influenza requires reliable estimates of mortality attributable to the seasonal influenza.MethodsExcess age-specific mortality during periods of influenza activity was evaluated in Israel during the period 1999–2006 for three death categories. For each respiratory year, the lowest monthly moving average for the mortality rate was subtracted from each month in the period of influenza activity. Average mortality rates in years with minimal influenza activity were deducted from corresponding months to exclude winter mortality unrelated to influenza. The sums of these results were used as estimates of excess mortality rates.ResultsOverall excess mortality rates ranged from 7.7 to 36.1 per 100,000 for all causes, and from 4.4 to 24.4 per 100,000 for respiratory and circulatory causes. Influenza was associated with an average of 869 (range 280–1,516) deaths annually from respiratory and circulatory diseases during seasons with significant influenza activity. About 90% of the influenza-associated mortality from respiratory and circulatory diseases was in the age group 65+ years and about 1% in the age group <50 years. The age group <50 years accounted for an annual average of seven deaths from respiratory and circulatory diseases.ConclusionAnnual mortality associated with seasonal influenza is highly variable. Under the age of 50 years, there is minimal seasonal influenza associated mortality. This information provides an important baseline for evaluating the severity of the A(H1N1) 2009 influenza pandemic, where persons under 50 years of age were often disproportionately represented.

Diabetes and the Severity of Pandemic Influenza A (H1N1) Infection

OBJECTIVETo confirm the existence of an increased risk of complications from influenza A (H1N1)p among patients with diabetes.RESEARCH DESIGN AND METHODSUsing data from an enhanced influenza surveillance project in Montreal, Canada, and age/sex-specific population estimates of diabetes prevalence, we estimated the risk of hospitalization among persons with diabetes. Comparing hospitalized patients admitted or not to an intensive care unit (ICU), we estimated the risk of ICU admission associated with diabetes, controlling for other patient characteristics.RESULTSAmong 239 hospitalized patients with PCR-confirmed influenza A (H1N1)p, 162 (68%) were interviewed, of whom 22 had diabetes, when 7.1 were expected (prevalence ratio 3.10 [95% CI 2.04–4.71]). The odds ratio for ICU admission was 4.29 (95% CI 1.29–14.3) among hospitalized patients with diabetes compared to those without.CONCLUSIONSDiabetes triples the risk of hospitalization after influenza A (H1N1)p and quadruples the risk of ICU admission once hospitalized.

The severity of pandemic H1N1 influenza in the United States, April -- July 2009.

BackgroundAccurate measures of the severity of pandemic influenza A/H1N1 (pH1N1) are needed to assess the likely impact of an anticipated resurgence in the autumn in the Northern Hemisphere. Severity has been difficult to measure because jurisdictions with large numbers of deaths and other severe outcomes have had too many cases to assess the total number with confidence. Also, detection of severe cases may be more likely. Methods and FindingsWe used complementary data from two US cities: Milwaukee attempted to identify cases of medically attended infection whether or not they required hospitalization, while New York City focused on the identification of hospitalizations, intensive care admission or mechanical ventilation (hereafter, ICU), and deaths. New York data were used to estimate numerators for ICU and death, and two sources of data: medically attended cases in Milwaukee or self-reported influenza-like illness in New York, were used to estimate ratios of symptomatic cases:hospitalizations. Combining these data with estimates of the fraction detected for each level of severity, we estimated the proportion of symptomatic cases that died (symptomatic case-fatality ratio, sCFR), required ICU (sCIR), and required hospitalization (sCHR), overall and by age category. Evidence, prior information and associated uncertainty were analyzed in a Bayesian evidence synthesis framework. Using medically attended cases and estimates of the proportion of symptomatic cases medically attended, we estimated sCFR of 0.048% (95% credible interval, CI 0.026%-0.096%), sCIR of 0.239% (0.134%-0.458%), and sCHR of 1.44% (0.83%-2.64%). Using self-reported ILI, we obtained estimates approximately 7-9x lower. sCFR and sCIR appear to be highest in persons 18 and older, and lowest in children 5-17. sCHR appears to be lowest in persons 5-17; our data were too sparse to allow us to determine the group in which it was the highest. ConclusionsThese estimates suggest that an autumn-winter pandemic wave of pH1N1 with comparable severity per case could lead to a number of deaths in the range from considerably below that associated with seasonal influenza to slightly higher, but with greatest impact in young children and non-elderly adults. These estimates of impact depend on assumptions about total incidence of infection and would be larger if incidence of symptomatic infection were higher or shifted toward adults, if viral virulence increased, or if suboptimal treatment resulted from stress on the health care system; numbers would decrease if the proportion infected or symptomatic were lower.

Trends in recorded influenza mortality: United States, 1900-2004.

I sought to describe trends in historical influenza mortality data in the United States since 1900 and compare pandemic with nonpandemic influenza seasons. I compiled a database of monthly influenza-classed death rates from official US mortality tables for the years 1900 to 2004 (1905-1909 excluded), from which I calculated adjusted influenza season (July 1-June 30) mortality rates. An overall and substantial decline in influenza-classed mortality was observed during the 20th century, from an average seasonal rate of 10.2 deaths per 100 000 population in the 1940s to 0.44 per 100 000 by the 1990s [corrected] . The 1918-1919 pandemic stands out as an exceptional outlier. The 1957-1958 and 1968-1969 influenza pandemic seasons, by contrast, displayed substantial overlap in both degree of mortality and timing compared with nonpandemic seasons. The considerable similarity in mortality seen in pandemic and non-pandemic influenza seasons challenges common beliefs about the severity of pandemic influenza. The historical decline in influenza-classed mortality rates suggests that public health and ecological factors may play a role in influenza mortality risk. Nevertheless, the actual number of influenza-attributable deaths remains in doubt.

Influenza pandemic preparedness: motivation for protection among small and medium businesses in Australia

BackgroundCommunity-wide preparedness for pandemic influenza is an issue that has featured prominently in the recent news media, and is currently a priority for health authorities in many countries. The small and medium business sector is a major provider of private sector employment in Australia, yet we have little information about the preparedness of this sector for pandemic influenza. This study aimed to investigate the association between individual perceptions and preparedness for pandemic influenza among small and medium business owners and managers.MethodsSemi-structured face-to-face interviews were conducted with 201 small and medium business owners or managers in New South Wales and Western Australia. Eligible small or medium businesses were defined as those that had less than 200 employees. Binomial logistic regression analysis was used to identify the predictors of having considered the impact of, having a plan for, and needing help to prepare for pandemic influenza.ResultsApproximately 6 per cent of participants reported that their business had a plan for pandemic influenza, 39 per cent reported that they had not thought at all about the impact of pandemic influenza on their business, and over 60 per cent stated that they required help to prepare for a pandemic. Beliefs about the severity of pandemic influenza and the ability to respond were significant independent predictors of having a plan for pandemic influenza, and the perception of the risk of pandemic influenza was the most important predictor of both having considered the impact of, and needing help to prepare for a pandemic.ConclusionOur findings suggest that small and medium businesses in Australia are not currently well prepared for pandemic influenza. We found that beliefs about the risk, severity, and the ability to respond effectively to the threat of pandemic influenza are important predictors of preparedness. Campaigns targeting small and medium businesses should emphasise the severity of the consequences to their businesses if a pandemic were to occur, and, at the same time, reassure them that there are effective strategies capable of being implemented by small and medium businesses to deal with a pandemic.

Low pH gel intranasal sprays inactivate influenza viruses in vitro and protect ferrets against influenza infection

BackgroundDeveloping strategies for controlling the severity of pandemic influenza is a global public health priority. In the event of a pandemic there may be a place for inexpensive, readily available, effective adjunctive therapies to support containment strategies such as prescription antivirals, vaccines, quarantine and restrictions on travel. Inactivation of virus in the intranasal environment is one possible approach. The work described here investigated the sensitivity of influenza viruses to low pH, and the activity of low pH nasal sprays on the course of an influenza infection in the ferret model.MethodsInactivation of influenza A and avian reassortment influenza was determined using in vitro solutions tests. Low pH nasal sprays were tested using the ferret model with an influenza A Sydney/5/97 challenge. Clinical measures were shed virus, weight loss and body temperature.ResultsThe virus inactivation studies showed that influenza viruses are rapidly inactivated by contact with acid buffered solutions at pH 3.5. The titre of influenza A Sydney/5/97 [H3N2] was reduced by at least 3 log cycles with one minute contact with buffers based on simple acid mixtures such as L-pyroglutamic acid, succinic acid, citric acid and ascorbic acid. A pH 3.5 nasal gel composition containing pyroglutamic acid, succinic acid and zinc acetate reduced titres of influenza A Hong Kong/8/68 [H3N2] by 6 log cycles, and avian reassortment influenza A/Washington/897/80 X A Mallard/New York/6750/78 [H3N2] by 5 log cycles, with 1 min contact.Two ferret challenge studies, with influenza A Sydney/5/97, demonstrated a reduction in the severity of the disease with early application of low pH nasal sprays versus a saline control. In the first study there was decreased weight loss in the treatment groups. In the second study there were reductions in virus shedding and weight loss, most notably when a gelling agent was added to the low pH formulation.ConclusionThese findings indicate the potential of a low pH nasal spray as an adjunct to current influenza therapies, and warrant further investigation in humans.