Differences in the epidemiological characteristics and clinical outcomes of pandemic (H1N1) 2009 influenza, compared with seasonal influenza

Comorbidities, Associated Diseases, and Risk Assessment in COVID-19-A Systematic Review

It is considered that COVID-19's pandemic expansion is responsible for the particular increase in deaths, especially among the population with comorbidities. The health system is often overwhelmed by the large number of cases of patients addressing it, by the regional limitation of funds, and by the gravity of cases at subjects suffering from this pathology. Several associated conditions including diabetes, cardiovascular illnesses, obesity, persistent lung condition, neurodegenerative diseases, etc., increase the mortality risk and hospitalization of subjects suffering from COVID-19. The rapid identification of patients with increased risk of death from the SARS-CoV-2 virus, the stratification in accordance with the risk and the allocation of human, financial, and logistical resources in proportion must be a priority for health systems worldwide.

Prevalence and impact of comorbidities on disease prognosis among patients with COVID-19 in Bangladesh: A nationwide study amid the second wave

BACKGROUND

Socio-demographics and comorbidities are involved in determining the severity and fatality in patients with COVID-19 suggested by studies in various countries, but study in Bangladesh is insufficient.

AIMS

We designed the study to evaluate the association of sociodemographic and comorbidities with the prognosis of adverse health outcomes in patients with COVID-19 in Bangladesh.

METHODS

A multivariate retrospective cohort study was conducted on data from 966 RT-PCR positive patients from eight divisions during December 13, 2020, to February 13, 2021. Variables included sociodemographic, comorbidities, symptoms, Charlson comorbidity index (CCI) and access to health facilities. Major outcome was fatality. Secondary outcomes included hospitalization, duration of hospital stay, requirement of mechanical ventilation and severity.

RESULTS

Male (65.8%, 636 of 966) was predominant and mean age was 39.8 ± 12.6 years. Fever (79%), dry cough (55%), and loss of test/smell (51%) were frequent and 74% patients had >3 symptoms. Fatality was recorded in 10.5% patients. Comorbidities were found in 44% patients. Hypertension (21.5%) diabetes (14.6%), and cardiovascular diseases (11.3%) were most prevalent. Age >60 years (OR: 4.83, 95% CI: 2.45-6.49), and CCI >3 (OR: 5.48, 95% CI: 3.95-7.24) were predictors of hospitalizations. CCI >4 (aOR: 3.41, 95% CI: 2.57-6.09) was predictor of severity. Age >60 years (aOR: 3.77, 95% CI: 1.07-6.34), >3 symptoms (aOR: 2.14, 95% CI: 0.97-4.91) and CCI >3 vs. CCI <3 (aOR: 5.23, 95% CI: 3.77-8.09) were independently associated with fatality.

CONCLUSIONS

Increased age, >3 symptoms, increasing comorbidities, higher CCI were associated with increased hospitalization, severity and fatality in patients with COVID-19.

Influence of age, sex and respiratory viruses on the rates of emergency department visits and hospitalisations with respiratory tract infections, asthma and COPD

Background

The importance of age, sex and respiratory virus prevalence in emergency department (ED) visits and hospitalisations for respiratory tract infections (RTIs), asthma and COPD in a whole population over time is not well established.

Methods

This study retrospectively analysed data for daily ED visits and hospitalisations from 2003 to 2013 in Ontario, Canada and the daily number of virus positive tests. Daily numbers of ED visits and hospitalisations with RTIs, asthma and COPD listed as a primary diagnosis were collected from the Canadian Institute for Health Information. Virus data were obtained from the Respiratory Virus Detection Surveillance System. Multiple linear regression was used to assess the association of individual viruses with the daily rates.

Results

There were 4 365 578 ED visits and 321 719 (7.4%) admissions for RTIs, 817 141 ED visits and 260 665 (31.9%) admissions for COPD and 649 666 ED visits and 68 626 (10.6%) admissions for asthma. Respiratory syncytial virus and influenza A were associated with male ED visits, whereas human rhinovirus was associated with female ED visits for RTIs in preschool children. 19.2% of males, but only 7.2% of females were admitted. The correlation between the prevalence of each virus and ED visits and hospitalisations for asthma was weak, irrespective of age group and sex. Influenza A was most strongly associated with COPD ED visits and hospitalisations in males and females.

Conclusions

There are significant age and sex differences in the contribution of respiratory viruses to the number of ED visits and hospitalisations for RTIs, asthma and COPD.

There are important age- and sex-related differences in the contribution of respiratory viruses to the number of ED visits and hospitalisations for respiratory tract infections, asthma and COPDhttps://bit.ly/39hrhIW

Comparable Disease Severity by Influenza Virus Subtype in the Acute Respiratory Infection Consortium Natural History Study

INTRODUCTION

Since the influenza A/H1N1 pandemic of 2009 to 2010, numerous studies have described the clinical course and outcome of the different subtypes of influenza (A/H1N1, A/H3N2, and B). A recent systematic literature review concluded that there were no appreciable differences in either clinical presentation or disease severity among these subtypes, but study parameters limit the applicability of these results to military populations. We sought to evaluate differences in disease severity among influenza subtypes in a cohort of healthy, primarily outpatient adult U.S. Department of Defense beneficiaries.

MATERIALS AND METHODS

From 2009 to 2014, we enrolled otherwise healthy adults age 18 to 65 years with influenza-like illness in an observational cohort study based in 5 U.S. military medical centers. Serial nasopharyngeal swabs were collected for determination of etiology and viral shedding by polymerase chain reaction. The presence and severity of symptoms was assessed by interview and patient diary.

RESULTS

Over a 5-year period, a total of 157 adults with laboratory-confirmed influenza and influenza subtype were enrolled. Of these, 69 (44%) were positive for influenza A(H1N1), 69 (44%) for influenza A(H3N2), and 19 (12%) for influenza B. About 61% were male, 64% were active duty military personnel, and 72% had received influenza vaccine in the past 8 months. Almost 10% were hospitalized with influenza. Seasonal influenza virus distribution among enrollees mirrored that of nationwide trends each year of study. Individuals with A/H1N1 had upper respiratory composite scores that were lower than those with A/H3N2. Multivariate models indicated that individuals with A(H1N1) and B had increased lower respiratory symptom scores when compared to influenza A(H3N2) (A[H1N1]: 1.51 [95% CI 0.47, 2.55]; B: 1.46 [95% CI 0.09, 2.83]), whereas no other differences in symptom severity scores among influenza A(H1N1), influenza A(H3N2), and influenza B infection were observed. Overall, influenza season (maximum in 2012-2013 season) and female sex of the participant were found to be associated with increased influenza symptom severity.

CONCLUSIONS

Our study of influenza in a cohort of otherwise healthy, outpatient adult Department of Defense beneficiaries over 5 influenza seasons revealed few differences between influenza A(H1N1), influenza A(H3N2), and influenza B infection with respect to self-reported disease severity or clinical outcomes. This study highlights the importance of routine, active, and laboratory-based surveillance to monitor ongoing trends and severity of influenza in various populations to inform prevention measures.

[Neuromuscular complications of SARS-CoV-2 infection-Part 2: muscle disorders]

Neben Störungen und Erkrankungen peripherer Nerven sind in den letzten Monaten im Zusammenhang mit COVID-19 („coronavirus disease 2019“) auch Begleitsymptome und Störungen der Muskulatur bzw. der neuromuskulären Transmission beschrieben worden. Im zweiten Teil unserer Zusammenfassung geben wir eine Übersicht über häufig berichtete Symptome wie Myalgien und definierte Erkrankungen wie Rhabdomyolysen, Myositiden, Myasthenie und „intensive care unit acquired weakness“ (ICUAW), die im Rahmen eine SARS-CoV-2(„severe acute respiratory syndrome coronavirus 2“)-Infektion bzw. COVID-19 beschrieben wurden. Darüber hinaus werden Kriterien für eine Kausalität wie Effektstärke, Plausibilität, Zeitverlauf und experimentelle Evidenz für einen kausalen Zusammenhang der in beiden Teilen der Übersicht beschriebenen COVID-19 assoziierten neuromuskulären Erkrankungen diskutiert. Zum jetzigen Zeitpunkt sind – neben der auch in der Laienpresse bekannten Geruchssinnstörung – vor allem Myalgien als unspezifisches Symptom häufige Folge einer symptomatischen SARS-CoV‑2 Infektion. Andere neuromuskuläre Komplikationen erscheinen hinsichtlich ihrer Pathogenese prinzipiell plausibel, aber offenbar selten Folge einer SARS-CoV-2-Infektion zu sein. Prospektive bzw. Kohortenstudien sind notwendig, um eine Kausalität zu bestätigen und das Risiko abzuschätzen.

Frequency of Comorbidities in Admitting COVID-19 Pneumonia Patients in a Tertiary Care Setup: An Observational Study

Background

The novel coronavirus disease 2019 (COVID-19) is a highly infectious and pandemic disease with a variable mode of action. Patients with underlying illnesses such as diabetes, hypertension, and other diseases are more prone to infection. An understanding of the different comorbidities that place patients at the highest risk of COVID-19 pneumonia and other fatal complications associated with COVID-19 is necessary for healthcare professionals. This study aimed to determine the frequency of different comorbid illnesses among COVID-19 patients admitted to a tertiary care hospital in Karachi, Pakistan.

Methodology

All patients diagnosed with COVID-19 who required admission for the care of their symptoms were included in this observational, cross-sectional study conducted from May 1 to July 30, 2020. The patients were treated at a specialized COVID-19 isolation ward built at the Dow University of Health Sciences at the Ojha campus. The patients were referred from the emergency department, medical and allied wards, and COVID-19 screening units. A detailed history and clinical examination were performed, and comorbidities were evaluated.

Results

A total of 212 patients were admitted during the study with a mean age of 52 ± 16 years. The study population consisted of 120 (56.6%) males and 92 (43.39%) females, and the most common comorbidities were uncontrolled diabetes with hypertension (n = 56; 26.4%), controlled diabetes (n = 22; 10.37%), obstructive airway disease (n = 16; 7.5%), and interstitial lung disease (n = 14; 6.6%). A total of 48 (22.64%) patients had no comorbidities.

Conclusions

Most COVID-19-positive patients with pneumonia were male, and common comorbidities included uncontrolled diabetes, hypertension, and obstructive and restrictive lung disease. The presence of comorbidities was associated with a marked increase in the risk of morbidity and mortality. Further studies are warranted to confirm these findings.

Chronic kidney disease predicts poor outcomes of COVID-19 patients

Purpose

The recent outbreak of COVID-19 rapidly spread worldwide. Comorbid diseases are determinants of the severity of COVID-19 infection and mortality. The aim of this study was to explore the potential association between chronic kidney disease (CKD) and the severity of COVID-19 infection.

Methods

The study included 609 consecutive adult patients (male: 54.52%, mean age: 59.23 ± 15.55 years) hospitalized with the diagnosis of COVID-19 in a tertiary level hospital. Data were collected from the electronic health records of the hospital. The patients were separated into two groups: Group I included COVID-19-positive patients with CKD stage 1–2, and Group II included COVID-19-positive with CKD stage 3–5. The relationships were examined between CKD stage, laboratory parameters and mortality.

Results

Significant differences were determined between the groups in respect of the inflammation parameters and the parameters used in prognosis. In Group II, statistically significantly higher rates were determined of comorbid diseases [hypertension (p < 0.001) and diabetes mellitus (p < 0.001), acute kidney injury (AKI), which was found to be associated with mortality (p < 0.001), and mortality (p < 0.001)]. In multivariate regression analysis, CKD stage 3–5, AKI, male gender, hypertension, DM and malignancy were found to be significant independent variables increasing mortality.

Conclusion

The prevelance of CKD stage 3–5 on admission is associated with a high risk of in-hospital mortality in patients with COVID-19. Close follow-up can be recommended for patients with a reduced glomerular filtration rate (GFR).

Comorbidities in Patients with COVID-19 and Their Impact on the Severity of the Disease

Infection with COVID-19 is associated with significant morbidity, especially in patients with chronic medical conditions. At least one-fifth of cases require supportive care in intensive care units, which have limited availability in most developing countries. A literature search was conducted on PubMed, Medline, Scopus, Embase, and Google Scholar to find articles published by May 7, 2020 on the role of comorbidities in patients with COVID-19 and the impact of comorbidities on the disease. This review highlighted that patients with comorbidities are more likely to experience severe disease than those with no other conditions; that is, comorbidities correlated with greater disease severity in patients with COVID-19. Proper screening of COVID-19 patients should include careful inquiries into their medical history; this will help healthcare providers identify patients who are more likely to develop serious disease or experience adverse outcomes. Better protection should also be given to patients with COVID-19 and comorbidities upon confirmation of the diagnosis. This literature review showed that the comorbidities most often associated with more severe cases of COVID-19 are hypertension, cardiovascular disease, and diabetes. Individuals with these comorbidities should adopt restrictive measures to prevent exposure to COVID-19, given their higher risk of severe disease.

Comorbidity and its impact on 1590 patients with COVID-19 in China: a nationwide analysis

Background

The coronavirus disease 2019 (COVID-19) outbreak is evolving rapidly worldwide.

Objective

To evaluate the risk of serious adverse outcomes in patients with COVID-19 by stratifying the comorbidity status.

Methods

We analysed data from 1590 laboratory confirmed hospitalised patients from 575 hospitals in 31 provinces/autonomous regions/provincial municipalities across mainland China between 11 December 2019 and 31 January 2020. We analysed the composite end-points, which consisted of admission to an intensive care unit, invasive ventilation or death. The risk of reaching the composite end-points was compared according to the presence and number of comorbidities.

Results

The mean age was 48.9 years and 686 (42.7%) patients were female. Severe cases accounted for 16.0% of the study population. 131 (8.2%) patients reached the composite end-points. 399 (25.1%) reported having at least one comorbidity. The most prevalent comorbidity was hypertension (16.9%), followed by diabetes (8.2%). 130 (8.2%) patients reported having two or more comorbidities. After adjusting for age and smoking status, COPD (HR (95% CI) 2.681 (1.424–5.048)), diabetes (1.59 (1.03–2.45)), hypertension (1.58 (1.07–2.32)) and malignancy (3.50 (1.60–7.64)) were risk factors of reaching the composite end-points. The hazard ratio (95% CI) was 1.79 (1.16–2.77) among patients with at least one comorbidity and 2.59 (1.61–4.17) among patients with two or more comorbidities.

Conclusion

Among laboratory confirmed cases of COVID-19, patients with any comorbidity yielded poorer clinical outcomes than those without. A greater number of comorbidities also correlated with poorer clinical outcomes.

The presence and number of comorbidities predict clinical outcomes of COVID-19http://bit.ly/3b9ibw5

Epidemiological and clinical characteristics of 333 confirmed cases with coronavirus disease 2019 in Shanghai, China

Coronavirus disease 2019 (COVID-19) is an emerging infectious disease first identified in Wuhan City, Hubei Province, China. As of 19 February 2020, there had been 333 confirmed cases reported in Shanghai, China. This study elaborates on the epidemiological and clinical characteristics of COVID-19 based on a descriptive study of the 333 patients infected with COVID-19 in Shanghai for the purpose of probing into this new disease and providing reference. Among the 333 confirmed cases in Shanghai, 172 (51.7%) were males and 161 (48.3%) were females, with a median age of 50 years. 299 (89.8%) cases presented mild symptoms. 139 (41.7%) and 111 (33.3%) cases were infected in Wuhan and Shanghai, respectively. 148 (44.4%) cases once had contact with confirmed cases before onset, while 103 (30.9%) cases had never contacted confirmed cases but they had a sojourn history in Wuhan. The onset date of the first case in Shanghai was 28 December, with the peak appearing on 27 January. The median incubation period of COVID-19 was estimated to be 7.2 days. 207 (62.2%) cases had fever symptoms at the onset, whereas 273 (82.0%) cases experienced fever before hospitalization. 56 (18.6%) adults experienced a decrease in white blood cell and 84 (42.9%) had increased C-reactive protein after onset. Elderly, male and heart disease history were risk factors for severe or critical pneumonia. These findings suggest that most cases experienced fever symptoms and had mild pneumonia. Strengthening the health management of elderly men, especially those with underlying diseases, may help reduce the incidence of severe and critical pneumonia. Time intervals from onset to visit, hospitalization and diagnosis confirmed were all shortened after Shanghai's first-level public health emergency response. Shanghai's experience proves that COVID-19 can be controlled well in megacities.

Comorbidity and its impact on 1590 patients with COVID-19 in China: a nationwide analysis

BACKGROUND

The coronavirus disease 2019 (COVID-19) outbreak is evolving rapidly worldwide.

OBJECTIVE

To evaluate the risk of serious adverse outcomes in patients with COVID-19 by stratifying the comorbidity status.

METHODS

We analysed data from 1590 laboratory confirmed hospitalised patients from 575 hospitals in 31 provinces/autonomous regions/provincial municipalities across mainland China between 11 December 2019 and 31 January 2020. We analysed the composite end-points, which consisted of admission to an intensive care unit, invasive ventilation or death. The risk of reaching the composite end-points was compared according to the presence and number of comorbidities.

RESULTS

The mean age was 48.9 years and 686 (42.7%) patients were female. Severe cases accounted for 16.0% of the study population. 131 (8.2%) patients reached the composite end-points. 399 (25.1%) reported having at least one comorbidity. The most prevalent comorbidity was hypertension (16.9%), followed by diabetes (8.2%). 130 (8.2%) patients reported having two or more comorbidities. After adjusting for age and smoking status, COPD (HR (95% CI) 2.681 (1.424-5.048)), diabetes (1.59 (1.03-2.45)), hypertension (1.58 (1.07-2.32)) and malignancy (3.50 (1.60-7.64)) were risk factors of reaching the composite end-points. The hazard ratio (95% CI) was 1.79 (1.16-2.77) among patients with at least one comorbidity and 2.59 (1.61-4.17) among patients with two or more comorbidities.

CONCLUSION

Among laboratory confirmed cases of COVID-19, patients with any comorbidity yielded poorer clinical outcomes than those without. A greater number of comorbidities also correlated with poorer clinical outcomes.

Post-pandemic influenza A/H1N1pdm09 is associated with more severe outcomes than A/H3N2 and other respiratory viruses in adult hospitalisations

This study compares the frequency and severity of influenza A/H1N1pdm09 (A/H1), influenza A/H3N2 (A/H3) and other respiratory virus infections in hospitalised patients. Data from 17 332 adult hospitalised patients admitted to Sir Charles Gairdner Hospital, Perth, Western Australia, with a respiratory illness between 2012 and 2015 were linked with data containing reverse transcription polymerase chain reaction results for respiratory viruses including A/H1, A/H3, influenza B, human metapneumovirus, respiratory syncytial virus and parainfluenza. Of these, 1753 (10.1%) had test results. Multivariable regression analyses were conducted to compare the viruses for clinical outcomes including ICU admission, ventilation, pneumonia, length of stay and death. Patients with A/H1 were more likely to experience severe outcomes such as ICU admission (OR 2.5, 95% CI 1.2–5.5, P = 0.016), pneumonia (OR 3.0, 95% CI 1.6–5.7, P < 0.001) and lower risk of discharge from hospital (indicating longer lengths of hospitalisation; HR 0.64 95% CI 0.47–0.88, P = 0.005), than patients with A/H3. Patients with a non-influenza respiratory virus were less likely to experience severe clinical outcomes than patients with A/H1, however, had similar likelihood when compared to patients with A/H3. Patients hospitalised with A/H1 had higher odds of severe outcomes than patients with A/H3 or other respiratory viruses. Knowledge of circulating influenza strains is important for healthcare preparedness.

Influenza A(H1N1)pdm09 and postpandemic influenza in Lithuania

The objective of this study is to describe the clinical and epidemiological characteristics of patients hospitalized in Lithuania who are infected with influenza A(H1N1)pdm09 and to compare pandemic A(H1N1) pdm09 infection with postpandemic.

In total, 146 subjects hospitalized with influenza A(H1N1) pdm09 were identified from 2009–2011. There were 53 during the initial pandemic wave in the summer of 2009, 69 during the peak pandemic period, and 24 during the “postpandemic” period that we included in this study. There were 22 subjects who died after laboratory confirmation of influenza A(H1N1)pdm09.

No deaths were documented during the first wave. Subjects presenting during the peak of pandemic influenza had a greater incidence of fever (100% vs 77.4%; p<0.001), dry cough (95.7% vs 82.7%; p=0.01), and vomiting (26.1% vs 1.9%, p<0.001) as compared with patients infected during the first wave. The rate of bacterial pneumonia was 18.8% (13/69) during the peak pandemic period and 12.5% (3/24, p=0.754) during the postpandemic period. None of the postpandemic influenza subjects’ intensive care unit stays were due to pneumonia.

The hospitalized early 2009 H1N1 pandemic cases and postpandemic cases were milder compared with those at the peak of pandemic activity.

Cost-effectiveness of an influenza vaccination program offering intramuscular and intradermal vaccines versus intramuscular vaccine alone for elderly

BACKGROUND

Intradermal (ID) injection is an alternative route for influenza vaccine administration in elderly with potential improvement of vaccine coverage. This study aimed to investigate the cost-effectiveness of an influenza vaccination program offering ID vaccine to elderly who had declined intramuscular (IM) vaccine from the perspective of Hong Kong public healthcare provider.

METHODS

A decision analytic model was used to simulate outcomes of two programs: IM vaccine alone (IM program), and IM or ID vaccine (IM/ID program) in a hypothetic cohort of elderly aged 65 years. Outcome measures included influenza-related direct medical cost, infection rate, mortality rate, quality-adjusted life years (QALYs) loss, and incremental cost per QALY saved (ICER). Model inputs were derived from literature. Sensitivity analyses evaluated the impact of uncertainty of model variables.

RESULTS

In base-case analysis, the IM/ID program was more costly (USD52.82 versus USD47.59 per individual to whom vaccine was offered) with lower influenza infection rate (8.71% versus 9.65%), mortality rate (0.021% versus 0.024%) and QALYs loss (0.00336 versus 0.00372) than the IM program. ICER of IM/ID program was USD14,528 per QALY saved. One-way sensitivity analysis found ICER of IM/ID program to exceed willingness-to-pay threshold (USD39,933) when probability of influenza infection in unvaccinated elderly decreased from 10.6% to 5.4%. In 10,000 Monte Carlo simulations of elderly populations of Hong Kong, the IM/ID program was the preferred option in 94.7% of time.

CONCLUSIONS

An influenza vaccination program offering ID vaccine to elderly who had declined IM vaccine appears to be a highly cost-effective option.

Comparison of age-specific hospitalization during pandemic and seasonal influenza periods from 2009 to 2012 in Taiwan: a nationwide population-based study

Background

Determining the age-specific hospitalization burden associated with seasonal influenza and the (H1N1) 2009 pandemic is important for the development of effective vaccine strategies and clinical management. The aim of this study was to investigate age-specific differences in hospitalization rates during the pandemic and seasonal periods.

Methods

Using the Taiwan National Health Insurance Research Database (NHIRD), we identified hospitalized patients with a principle discharge diagnosis of influenza-related infection (ICD-9-CM 487) between 2009 and 2012.

Results

Based on the time distribution of influenza-related hospitalizations and previously reported epidemic periods, the first and second waves of the (H1N1) 2009 pandemic (p1 is known as 2009.07-2010.01, and p2 is known as 2010.12-2011.03) and three seasonal periods (s1 is known as 2010.03-2010.11, s2 is known as 2011.10-2012.03, and s3 is known as 2012.04-2012.10) were found. During these five periods, children younger than 7 years of age consistently had the highest hospitalization rate of the studied age groups. In individuals younger than 50 years of age, the seasonal periods were associated with a significantly lower risk of hospitalization than that of p1 (Relative risk (RR) range = 0.18–0.85); however, they had a significantly higher hospitalization risk for adults over 50 years of age (RR = 1.51–3.22). Individuals over 50 years of age also had a higher intensive care unit admission rate and case fatality ratio than individuals under than 50 years of age during the seasonal periods and especially during the pandemic periods.

Conclusions

In both pandemic and seasonal periods, the highest hospitalization rate was observed for children younger than 7 years of age. Adults over 50 years of age had a higher hospitalization risk during the seasonal periods and a higher clinical severity during the pandemic periods. Those results emphasize that the importance of influenza-related prevention strategies in the younger and older age groups, either seasonal or pandemic periods.

Demographic and clinical characteristics of deaths associated with influenza A(H1N1) pdm09 in Central America and Dominican Republic 2009-2010

BACKGROUND

The demographic characteristics of pandemic influenza decedents among middle and low-income tropical countries are poorly understood. We explored the demographics of persons who died with influenza A (H1N1)pdm09 infection during 2009-2010, in seven countries in the American tropics.

METHODS

We used hospital-based surveillance to identify laboratory-confirmed influenza deaths in Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, Panama and Dominican Republic. An influenza death was defined as a person who died within two weeks of a severe acute respiratory infection (SARI) defined as sudden onset of fever >38 °C, cough or sore-throat, and shortness of breath, or difficulty breathing requiring hospitalization, and who tested positive for influenza A (H1N1)pdm09 virus by real time polymerase chain reaction. We abstracted the demographic and clinical characteristics of the deceased from their medical records.

RESULTS

During May 2009-June 2010, we identified 183 influenza deaths. Their median age was 32 years (IQR 18-46 years). One-hundred and one (55 %) were female of which 20 (20 %) were pregnant and 7 (7 %) were in postpartum. One-hundred and twelve decedents (61 %) had pre-existing medical conditions, (15 % had obesity, 13 % diabetes, 11 % asthma, 8 % metabolic disorders, 5 % chronic obstructive pulmonary disease, and 10 % neurological disorders). 65 % received oseltamivir but only 5 % received it within 48 h of symptoms onset.

CONCLUSIONS

The pandemic killed young adults, pregnant women and those with pre-existing medical conditions. Most sought care too late to fully benefit from oseltamivir. We recommend countries review antiviral treatment policies for people at high risk of developing complications.

An under-recognized influenza epidemic identified by rapid influenza testing, southern Sri Lanka, 2013

Influenza accounts for a large burden of acute respiratory tract infections in high-income countries; data from lower-income settings are limited due to lack of confirmatory testing. Consecutive outpatients presenting to the largest tertiary care hospital in southern Sri Lanka were surveyed for influenza-like illness (ILI), defined as acute onset of fever ≥ 38.0°C and cough. Patients were administered a questionnaire and nasal/nasopharyngeal sampling for rapid influenza A/B testing. We enrolled 311 patients with ILI from March to November 2013: 170 (54.7%) children and 172 (55.3%) males. Approximately half (147, 47.3%) tested positive for influenza, but 253 (81.4%) were prescribed antibiotics. On bivariable analysis, symptoms associated with influenza included pain with breathing (P < 0.001), headache (P = 0.005), fatigue (P = 0.003), arthralgias (P = 0.003), and myalgias (P = 0.006) in children and pain with breathing (P = 0.01), vomiting (P = 0.03), and arthralgias (P = 0.03) in adults. Our final clinical predictive models had low sensitivity and fair specificity-50.0% (95% CI: 38.6-61.4%) and 83.2% (95% CI: 73.4-90.0%), respectively, in children and 52.2% (95% CI: 39.9-64.2%) and 81.4% (95% CI: 70.0-89.4%), respectively, in adults. Our study confirms the ability of rapid influenza testing to identify an influenza epidemic in a setting in which testing is not routinely available.

Exploring national surveillance for health-related workplace absenteeism: lessons learned from the 2009 influenza A pandemic

BACKGROUND

During the 2009 influenza A (H1N1) virus pandemic, the Centers for Disease Control and Prevention did a pilot study to test the feasibility of using national surveillance of workplace absenteeism to assess the pandemic's impact on the workplace to plan for preparedness and continuity of operations and to contribute to health awareness during the emergency response.

METHODS

Population-based and sentinel worksite approaches were used. Monthly measures of the 1-week prevalence of health-related absenteeism among full-time workers were estimated using nationally representative data from the Current Population Survey. Enhanced passive surveillance of absenteeism was conducted using weekly data from a convenience sample of sentinel worksites.

RESULTS

Nationally, the pandemic's impact on workplace absenteeism was small. Estimates of 1-week absenteeism prevalence did not exceed 3.7%. However, peak workplace absenteeism was correlated with the highest occurrence of both influenza-like illness and influenza-positive laboratory tests.

CONCLUSIONS

Systems for monitoring workplace absenteeism should be included in pandemic preparedness planning.

Postpandemic Influenza A/H1N1pdm09 is still Causing Severe Perinatal Complications

Although influenza A/H1N1pdm09 is not causing a pandemic anymore, we recently observed two critically ill pregnant women infected by this virus. We present these cases to illustrate the possible severe complications of an – at that moment – seasonal influenza in pregnancy. We discuss the epidemiological differences between the pandemic and post pandemic phase and try to explain the high virulence of influenza A/H1N1pdm09 -infections in pregnancy by discussing insights in immunology during pregnancy. We conclude that although influenza A/H1N1pdm09 is in the post pandemic phase, infection by this influenza virus still needs to be considered in pregnant women with progressive respiratory dysfunction.

CDC Pregnancy Flu Line: monitoring severe illness among pregnant women with influenza

The Centers for Disease Control and Prevention implemented the Pregnancy Flu Line (PFL) during the influenza A(H1N1)pdm09 (pH1N1) pandemic and continued operation through the 2010-2011 influenza season to collect reports of intensive care unit (ICU) admissions and deaths among pregnant women with influenza. The system documented the severe impact of influenza on pregnant women during both seasons with 181 ICU/survivals and 37 deaths reported during the 2009 fall pandemic wave and 69 ICU/survivals and ten deaths reported in the subsequent influenza season (2010-2011). A health department survey suggests PFL participants perceived public health benefits and minimum time burdens.

Influenza epidemiology and vaccine effectiveness among patients with influenza-like illness, viral watch sentinel sites, South Africa, 2005-2009

Background

There is limited data on the epidemiology of influenza and few published estimates of influenza vaccine effectiveness (VE) from Africa. In April 2009, a new influenza virus strain infecting humans was identified and rapidly spread globally. We compared the characteristics of patients ill with influenza A(H1N1)pdm09 virus to those ill with seasonal influenza and estimated influenza vaccine effectiveness during five influenza seasons (2005–2009) in South Africa.

Methods

Epidemiological data and throat and/or nasal swabs were collected from patients with influenza-like illness (ILI) at sentinel sites. Samples were tested for seasonal influenza viruses using culture, haemagglutination inhibition tests and/or polymerase chain reaction (PCR) and for influenza A(H1N1)pdm09 by real-time PCR. For the vaccine effectiveness (VE) analysis we considered patients testing positive for influenza A and/or B as cases and those testing negative for influenza as controls. Age-adjusted VE was calculated as 1-odds ratio for influenza in vaccinated and non-vaccinated individuals.

Results

From 2005 through 2009 we identified 3,717 influenza case-patients. The median age was significantly lower among patients infected with influenza A(H1N1)pdm09 virus than those with seasonal influenza, 17 and 27 years respectively (p<0.001). The vaccine coverage during the influenza season ranged from 3.4% in 2009 to 5.1% in 2006 and was higher in the ≥50 years (range 6.9% in 2008 to 13.2% in 2006) than in the <50 years age group (range 2.2% in 2007 to 3.7% in 2006). The age-adjusted VE estimates for seasonal influenza were 48.6% (4.9%, 73.2%); −14.2% (−9.7%, 34.8%); 12.0% (−70.4%, 55.4%); 67.4% (12.4%, 90.3%) and 29.6% (−21.5%, 60.1%) from 2005 to 2009 respectively. For the A(H1N1)pdm09 season, the efficacy of seasonal vaccine was −6.4% (−93.5%, 43.3%).

Conclusion

Influenza vaccine demonstrated a significant protective effect in two of the five years evaluated. Low vaccine coverage may have reduced power to estimate vaccine effectiveness.

Brief education to increase uptake of influenza vaccine among pregnant women: a study protocol for a randomized controlled trial

Background

Pregnant women are the highest priority group for annual influenza vaccination. Studies have shown unacceptably low uptake of both seasonal and pandemic A/H1N1 influenza vaccination among pregnant women. This paper will describe the study protocol and methodology of a randomised controlled trial designed to assess the effectiveness of a brief educational intervention in improving the uptake of seasonal influenza vaccine among pregnant women in Hong Kong.

Methods

A randomised controlled trial will be conducted with pregnant women in at least the second trimester of pregnancy from four publicly funded hospital antenatal clinics in Hong Kong. Participants will be randomly assigned to either one of the two treatment groups: standard care (control) or standard care plus brief education (intervention). Pregnant women in the standard care group will receive the usual antenatal care with an educational pamphlet developed by the Hong Kong Centre for Health Protection and those in the intervention group will be provided with usual care plus a brief ten-minute education intervention. Content of the education session will cover four core components recommended in the research literature. The primary study outcome will be the proportion of participants who have received influenza vaccine during their pregnancy. A total of 184 pregnant women (92 per group) will be required to give an 80% power to detect a treatment effect of 15%.

Discussion

Most intervention studies aimed at improving influenza vaccination rates in pregnant women have targeted obstetric-care providers and the results of the two patient-oriented RCT interventions are conflicting. The high priority for vaccination given to pregnant women and the low influenza vaccination rate among pregnant women worldwide strongly indicates a need for interventions to improve uptake.

Trial registration

This trial is registered with the Clinical Trials Registry at www.clinicaltrials.gov(NCT01772901).

Serological response of patients with influenza A (H1N1) pdm09-associated pneumonia: an observational study

Background

Little is known about the dynamics or magnitude of antibody response in patients with influenza A (H1N1) pdm09-associated pneumonia. We described and compared the antibody response to influenza A (H1N1) pdm09 in patients with and without pneumonia.

Methods

We collected serum samples and determined antibody titers by the hemagglutination inhibition (HI) and microneutralization (mNT) assays from patients with RT-PCR confirmed influenza A (H1N1) pdm09 virus at baseline, 1, 2 and 6 months after onset of illness.

Results

Fifty-nine patients were enrolled, 45 (76.3%) were between 15 and 60 years of age, 49 (83.1%) were hospitalized and 25 (42.4%) had complications with pneumonia. Ninety-four percent of patients had HI titers ≥ 1: 40 and 90% had mNT titers ≥ 1: 160 at 2 months after illness. Geometric mean titers (GMT) of HI and mNT increased significantly (p<0.001) between baseline and months 1 or 2, then declined significantly (p<0.001) at month 6 by the HI assay, but dropped to an insignificant level (p=0.24) by the mNT assay. The mNT-GMT was at least twice as high as corresponding HI antibodies over a 6 month period. The GMT of HI and mNT in those with pneumonia (1 mo) peaked earlier than that of those without pneumonia (2 mo). When adjusted by age and gender, those with pneumonia had a higher HI-GMT than those without pneumonia at 1 month (264 vs. 117, p=0.007), 2 months (212 vs. 159, p=0.013), and 6 months (160 vs. 82, p=0.018).

Conclusions

The patients recovered from influenza A (H1N1) pdm09-associated pneumonia, clearly developed an earlier and more robust antibody response until 6 months after onset of illness. The results in our study are useful to determine an appropriate donor and timing to obtain convalescent plasma for adjunctive treatment of seriously ill patients with pandemic H1N1 influenza.

Clinical differences between influenza A (H1N1) pdm09 & influenza B infections identified through active community surveillance in North India

BACKGROUND & OBJECTIVES

Most studies on the clinical presentation with influenza viruses have been conducted in outpatient or inpatient medical facilities with only a few studies in community settings. Clinical differences between influenza A (H1N1) pdm 09 and influenza B virus infections have importance for community-based public health surveillance. An active community surveillance at the time of emergence of pandemic influenza provided us with an opportunity to compare the clinical features among patients infected with influenza A (H1N1) pdm09 virus and those with influenza B virus co-circulating in an active community-based weekly surveillance in three villages in Faridabad, Haryana, north India.

METHODS

Active surveillance for febrile acute respiratory infection (FARI) was carried out in a rural community (n=16,182) in the context of an inactivated trivalent influenza vaccine trial (among children <11 yr). Individuals with FARI were assessed clinically by nurses and respiratory samples collected and tested for influenza viruses by real time RT-PCR from November 2009 to August 2010. Clinical symptoms of patients with influenza A (H1N1) pdm 09 and influenza B infection were compared.

RESULTS

Of the 4796 samples tested, 822 (17%) were positive for influenza virus. Of these, 443 (54%) were influenza A (H1N1) pdm09, 373 (45%) were influenza B and six were other subtypes/mixed infections. The mean age was lower for patients with influenza B (16.4 yr) than influenza A (H1N1) pdm09 infection (18.7 yr; P=0.04). Among children aged 5-18 yr, chills/rigours (OR 4.0; CI 2.2, 7.4), sore throat (OR 6.8; CI 2.3, 27.3) and headache (OR2.0; CI 1.3, 3.3) were more common in influenza A (H1N1) pdm09 infection than in influenza B cases. Chills/rigours (OR 2.4; CI 1.4, 4.0) and headache (OR 1.7; CI 1.0, 2.7) were associated with influenza A (H1N1) pdm09 infection in those >18 yr. No significant differences were seen in children <5 yr.

CONCLUSION

Our findings show that the differences in the clinical presentation of influenza A(H1N1)pdm09 and influenza B infections are not likely to be of clinical or public health significance.

Understanding the burden of influenza infection among adults in Canadian hospitals: a comparison of the 2009-2010 pandemic season with the prepandemic and postpandemic seasons

BACKGROUND

The degree to which the 2009-2010 influenza pandemic season differed from previous and subsequent influenza seasons in Canadian hospitals has not yet been assessed.

METHODS

Surveillance for laboratory-confirmed influenza among adults in 51 Canadian Nosocomial Infection Surveillance Program hospitals was conducted between November 1, 2006, and May 31, 2011. Inpatient characteristics, treatment, and outcomes of influenza cases in the pandemic season (2009-2010) were compared with those in the prepandemic (2006-2007 to 2008-2009) and postpandemic (2010-2011) seasons.

RESULTS

The incidence of influenza infection was lower in the postpandemic season (1.59/1,000 admissions) compared with the prepandemic seasons (2.00/1,000 admissions; P < .001) and the pandemic season (1.80/1,000 admissions; P < .001). The proportion of cases classified as health care-associated was much smaller during the pandemic season (6.6%) than in either the prepandemic season (23.2%; P < .001) or the postpandemic season (23.6%; P < .001). Inpatients in the pandemic season were significantly younger compared with those in the prepandemic and postpandemic seasons (P < .001). Inpatients in the pandemic season were less likely to have been vaccinated (P < .001), but more likely to be treated with antiviral agents (P < .001), than inpatients in both the prepandemic and postpandemic seasons. Intensive care unit admission was greater during the pandemic season, but there were no significant differences in 30-day mortality among the seasons.

CONCLUSIONS

Among adult inpatients, the pH1N1 pandemic season differed from seasonal influenza in terms of age, vaccination status, antiviral use, and intensive care unit admission, but not in terms of 30-day mortality.

Assessing Healthcare Utilization for Influenza-like Illness at an Emergency Department and a Student Health Service during the 2009-2010 H1N1 Pandemic

Estimates of healthcare utilization during an influenza pandemic are needed in order to plan for the allocation of staff and resources. The aim of this study was to assess the number, age, and arrival time of patients with influenza-like-illness (ILI), and associations between their symptoms during the 2009-2010 H1N1 pandemic. We conducted a cross-sectional analysis of electronic health records from the student health service (SHS) and an emergency department (ED) in Morgantown, West Virginia, between January 2009 and December 2010. During the 2009-2010 H1N1 pandemic, patient arrivals at SHS and ED varied over the week. SHS patients arrived early in the week and primarily in the afternoon. ED patient arrivals were more evenly distributed, with busier evenings and weekends. Those with fever were more likely to experience cough, sore throat, vomiting/nausea, chills, congestion, headache, and body-ache. These results can assist health professionals in preparing for an influenza pandemic.

Emergency Physicians' Adherence to Center for Disease Control and Prevention Guidance During the 2009 Influenza A H1N1 Pandemic

INTRODUCTION

Little is known regarding compliance with management guidelines for epidemic influenza in adult emergency department (ED) settings during the 2009 novel influenza A (H1N1) epidemic, especially in relation to the Centers for Disease Control and Prevention (CDC) guidance.

METHODS

We investigated all patients with a clinical diagnosis of influenza at an inner-city tertiary academic adult ED with an annual census of approximately 60,000 visits from May 2008 to December 2009. We aimed to determine patterns of presentation and management for adult patients with an ED diagnosis of influenza during the H1N1 pandemic, using seasonal influenza (pre-H1N1) as reference and to determine the ED provider's adherence to American College of Emergency Physicians and CDC guidance during the 2009 H1N1 influenza pandemic. Adherence to key elements of CDC 2009 H1N1 guidance was defined as (1) the proportion of admitted patients who were recommended to receive testing or treatment who actually received testing for influenza or treatment with antivirals; and (2) the proportion of high-risk patients who were supposed to be treated who actually were treated with antivirals.

RESULTS

Among 339 patients with clinically diagnosed influenza, 88% occurred during the H1N1 pandemic. Patients were similarly managed during both phases. Median length of visit (pre-H1N1: 385 min, H1N1: 355 min, P > 0.05) and admission rates (pre-H1N1: 8%, H1N1: 11%, P > 0.05) were similar between the 2 groups. 28% of patients in the pre-H1N1 group and 16% of patients in the H1N1 group were prescribed antibiotics during their ED visits (P > 0.05). There were 34 admitted patients during the pandemic;, 30 (88%) of them received influenza testing in the ED, and 22 (65%) were prescribed antivirals in the ED. Noticeably, 19 (56%) of the 34 admitted patients, including 6 with a positive influenza test, received antibiotic treatment during their ED stay.

CONCLUSION

During the recent H1N1 pandemic, most admitted patients received ED diagnostic testing corresponding to the current recommended guidance. Antibiotic treatment for ED patients admitted with suspected influenza is not uncommon. However, less than 70% of admitted patients and less than 50% of high-risk patients were treated with antivirals during their ED visit, indicating a specific call for closer adherence to guidelines in future influenza pandemics.

Clinical features and outcomes of influenza A and B infections in children

The aim of the study was to describe the course of influenza among children aged 0-59 months. A total of 150 children with influenza-like symptoms (ILI): cough, fever >37.8 °C, and sore throat was included into the observation. All children were tested with both rapid influenza detection test (RIDT) BD Directigen™ EZ Flu A+B® and RT-PCR. Sixty four cases of influenza were diagnosed (incidence rate 40 %): 19 (30 %) cases of influenza caused by type B virus and 45 (70 %) cases caused by type A virus. Children with influenza required more often follow up visits (p < 0.05, OR 1.99, 95 % CI 1.03-3.85) and less often were administrated antibiotic therapy (p < 0.05, OR 0.25, 95 % CI 0.04-0.97). The logistic regression analysis revealed that only positive result of rapid influenza detection test, not any of clinical symptoms, could be found as an independent predictor of influenza (OR 4.37, 95 % CI 2.03-9.43). Patients with influenza type A more often reported muscle ache (p < 0.05) and complications (p < 0.05; OR 6.06, 95 % CI 1.20-60.38). Otitis media occurred more often among patients with than without influenza (p < 0.01; OR 15.50, 95 % CI 2.10-688.5). We conclude that although influenza infections among children younger than 59 months were generally mild and self-limited, pediatric burden of the disease was significant.

A large, population-based study of 2009 pandemic Influenza A virus subtype H1N1 infection diagnosis during pregnancy and outcomes for mothers and neonates

BACKGROUND

Pregnant women were at increased risk for serious outcomes of 2009 pandemic influenza A virus subtype H1N1 (influenza A[H1N1]pdm09) infection, but little is known about the overall impact of the pandemic on neonatal and maternal outcomes.

METHODS

We identified live births that occurred from 1 July 2008 through 31 May 2010 in 5 Kaiser Permanente regions. Pregnant women were considered to have influenza if they had a positive result of a laboratory test for influenza virus or if they received a diagnosis of influenza during a period in which seasonal influenza virus or A(H1N1)pdm09 was the predominant circulating virus.

RESULTS

There were 111 158 births from 109 015 pregnancies involving 107 889 mothers; 368 pregnant women (0.3%) received a diagnosis of influenza due to seasonal virus, and 959 (0.9%) received a diagnosis of influenza due to A(H1N1)pdm09; 107 688 did not receive an influenza diagnosis. Pregnant women with influenza due to A(H1N1)pdm09 were more likely than women with seasonal influenza infection to be hospitalized within 30 days of the diagnosis (27% vs 12%; odds ratio [OR], 2.84 [95% confidence interval {CI}, 2.01-4.02]). Pregnant women with A(H1N1)pdm09 who started antiviral treatment ≥2 days after the diagnosis were significantly more likely to be hospitalized than those who started antiviral treatment <2 days after diagnosis (OR, 3.43 [95% CI, 1.55-7.56]). Mothers with seasonal influenza virus infection had an increased risk for having a small-for-gestational-age infant (OR, 1.59 [95% CI, 1.15-2.20]).

CONCLUSIONS

In this large, geographically diverse population, A(H1N1)pdm09 infection increased the risk for hospitalization during pregnancy. Late initiation of antiviral treatment was also associated with an increased risk for hospitalization.

Surveillance of hospitalised severe cases of influenza A(H1N1)pdm09 and related fatalities in nine EU countries in 2010-2011

A few months into the 2009 influenza pandemic, nine European countries implemented case-based surveillance of hospitalised severe influenza infections. In the present study, we assess the association between patient characteristics, in particular underlying conditions, and the severity level of influenza A(H1N1)pdm09 infection during the 2010-2011 season. Patient age, the presence of underlying conditions, pneumonia, acute respiratory distress syndrome (ARDS) and the need for ventilation were significantly associated with the severity of influenza A(H1N1)pdm09 infection. Despite limitations essentially because of the heterogeneity of the data reported, this study provides insight into severe influenza cases.

Heterogeneous virulence of pandemic 2009 influenza H1N1 virus in mice

BACKGROUND

Understanding the pathogenesis of influenza infection is a key factor leading to the prevention and control of future outbreaks. Pandemic 2009 Influenza H1N1 infection, although frequently mild, led to a severe and fatal form of disease in certain cases that make its virulence nature debatable. Much effort has been made toward explaining the determinants of disease severity; however, no absolute reason has been established.

RESULTS

This study presents the heterogeneous virulence of clinically similar strains of pandemic 2009 influenza virus in human alveolar adenocarcinoma cells and mice. The viruses were obtained from patients who were admitted in a local hospital in China with a similar course of infection and recovered. The A/Nanchang/8002/2009 and A/Nanchang/8011/2009 viruses showed efficient replication and high lethality in mice while infection with A/Nanchang/8008/2009 was not lethal with impaired viral replication, minimal pathology and modest proinflammatory activity in lungs. Sequence analysis displayed prominent differences between polymerase subunits (PB2 and PA) of viral genomes that might correlate with their different phenotypic behavior.

CONCLUSIONS

The study confirms that biological heterogeneity, linked with the extent of viral replication, exists among pandemic H1N1 strains that may serve as a benchmark for future investigations on influenza pathogenesis.

Essential role of IL-6 in protection against H1N1 influenza virus by promoting neutrophil survival in the lung

Influenza virus infection is considered a major worldwide public health problem. Seasonal infections with the most common influenza virus strains (e.g., H1N1) can usually be resolved, but they still cause a high rate of mortality. The factors that influence the outcome of the infection remain unclear. Here, we show that deficiency of interleukin (IL)-6 or IL-6 receptor is sufficient for normally sublethal doses of H1N1 influenza A virus to cause death in mice. IL-6 is necessary for resolution of influenza infection by protecting neutrophils from virus-induced death in the lung and by promoting neutrophil-mediated viral clearance. Loss of IL-6 results in persistence of the influenza virus in the lung leading to pronounced lung damage and, ultimately, death. Thus, we demonstrate that IL-6 is a vital innate immune cytokine in providing protection against influenza A infection. Genetic or environmental factors that impair IL-6 production or signaling could increase mortality to influenza virus infection.

[A(H1N1)v cases of the 2009/2010 and 2010/2011 influenza seasons in the Medical and Health Sciences Centre of Debrecen University]

The swine-origin new influenza variant A(H1N1) emerged in 2009 and changed the epidemiology of the 2009/2010 influenza season globally and at national level.

AIMS

The aim of the authors was to analyse the cases of two influenza seasons.

METHODS

The Medical and Health Sciences Centre of Debrecen University has 1690 beds with 85 000 patients admitted per year. The diagnosis of influenza was conducted using real-time polymerase chain reaction in the microbiological laboratories of the University and the National Epidemiological Centre, according to the recommendation of the World Health Organization.

RESULTS

The incidence of influenza was not higher than that observed in the previous season, but two high-risk patient groups were identified: pregnant women and patients with immunodeficiency (oncohematological and organ transplant patients). The influenza vaccine, which is free for high-risk groups and health care workers in Hungary, appeared to be effective for prevention, because in the 2010/2011 influenza season none of the 58 patients who were administered the vaccination developed influenza.

CONCLUSION

It is an important task to protect oncohematological and organ transplant patients.

Influenza-like illness in Norway: clinical course, attitudes towards vaccination and preventive measures during the 2009 pandemic

OBJECTIVES

To document clinical characteristics of influenza-like illness, reported use of health preventive measures and attitudes towards vaccination among patients with influenza-like illness in general practice during the influenza pandemic in 2009.

METHODS

Cross-sectional survey in general practice. Patients, who were identified as having influenza-like illness during the peak of the influenza pandemic activity in Norway, were eligible for inclusion in the study. A questionnaire was sent 2-4 weeks after the patients visit to the GP with influenza-like illness diagnosis during October to December 2009, from general practices in Norway. A sample of responders >18 years also had a blood test to check for serological response to the pandemic H1N1 virus.

RESULTS

Questionnaires were sent to 1324 patients, and 357 (27%) were returned. Fever (91% versus 49%, P < 0.01), cough (85% versus 73%, P = 0.016) and gastrointestinal symptoms (58% versus 38%, P < 0.01) were more frequent in the age group <18 years compared to older patients. Serological H1N1 responses were analysed in 72 patients; 34 (47%) were positive (haemagglutination inhibition assay titres ≥ 40). There were no statistically significant differences in symptoms between seropositive and seronegative patients. Women reported better adherence to personal protective measures, such as hand washing and cough etiquette than men. Women were also more concerned about possible adverse effects of the pandemic influenza vaccine than men.

CONCLUSIONS

Discrimination between influenza and other viral upper respiratory tract infections is difficult in daily clinical practice, even during an influenza pandemic. A gender difference was found in reported precautions to prevent influenza.

A cost-effectiveness analysis of "test" versus "treat" patients hospitalized with suspected influenza in Hong Kong

BACKGROUND

Seasonal and 2009 H1N1 influenza viruses may cause severe diseases and result in excess hospitalization and mortality in the older and younger adults, respectively. Early antiviral treatment may improve clinical outcomes. We examined potential outcomes and costs of test-guided versus empirical treatment in patients hospitalized for suspected influenza in Hong Kong.

METHODS

We designed a decision tree to simulate potential outcomes of four management strategies in adults hospitalized for severe respiratory infection suspected of influenza: "immunofluorescence-assay" (IFA) or "polymerase-chain-reaction" (PCR)-guided oseltamivir treatment, "empirical treatment plus PCR" and "empirical treatment alone". Model inputs were derived from literature. The average prevalence (11%) of influenza in 2010-2011 (58% being 2009 H1N1) among cases of respiratory infections was used in the base-case analysis. Primary outcome simulated was cost per quality-adjusted life-year (QALY) expected (ICER) from the Hong Kong healthcare providers' perspective.

RESULTS

In base-case analysis, "empirical treatment alone" was shown to be the most cost-effective strategy and dominated the other three options. Sensitivity analyses showed that "PCR-guided treatment" would dominate "empirical treatment alone" when the daily cost of oseltamivir exceeded USD18, or when influenza prevalence was <2.5% and the predominant circulating viruses were not 2009 H1N1. Using USD50,000 as the threshold of willingness-to-pay, "empirical treatment alone" and "PCR-guided treatment" were cost-effective 97% and 3% of time, respectively, in 10,000 Monte-Carlo simulations.

CONCLUSIONS

During influenza epidemics, empirical antiviral treatment appears to be a cost-effective strategy in managing patients hospitalized with severe respiratory infection suspected of influenza, from the perspective of healthcare providers in Hong Kong.

Severity of pandemic H1N1 2009 influenza virus infection may not be directly correlated with initial viral load in upper respiratory tract

Please cite this paper as: Wu et al. (2012) Severity of pandemic H1N1 2009 influenza virus infection may not be directly correlated with initial viral load in upper respiratory tract. Influenza and Other Respiratory Viruses 6(5), 367–373.

Background  Recent studies have demonstrated that rapid influenza diagnostic tests (RIDTs) have a relatively low sensitivity in detecting severe cases of pandemic H1N1 2009 influenza virus (pH1N1) infection. We hypothesized that viral load in upper respiratory specimens obtained on presentation may not be correlated with disease severity.

Methods  We conducted a prospective study to compare patterns of viral shedding using nasopharyngeal swab specimens, according to the number of days of post‐symptom onset and post‐antiviral therapy, between patients with and without complications.

Results  From July 15, 2009 through July 23, 2010, we collected and processed a total of 141 nasopharyngeal swab specimens from 64 inpatients and outpatients with laboratory‐confirmed pH1N1 infection. These included 46 patients without any complications (uncomplicated group) and 18 patients who required hospital admission (complicated group). The mean initial viral load was higher in the uncomplicated group than in the complicated group (3·4 ± 1·6 log₁₀ copies/μl versus 1·9 ± 1·7, P = 0·02). However, prolonged viral shedding was only detected in the complicated group (44% by day 7 of antiviral therapy). By multivariate analysis, we found that age (OR, 1·1; 95% CI, 1·0–1·1) and initial nasopharyngeal viral load (OR, 0·5; 95% CI, 0·3–0·8) were significant factors associated with complications.

Conclusion  Given that patients with severe pH1N1 infection may have relatively lower initial viral load in the upper respiratory tract, cautious interpretation of negative RIDT results is particularly warranted in this patient population.

Clinical and nonclinical health care workers faced a similar risk of acquiring 2009 pandemic H1N1 infection

Reporting of confirmed pandemic influenza A virus (pH1N1) 2009 infection was mandatory among health care workers in Hong Kong. Among 1158 confirmed infections, there was no significant difference in incidence among clinical versus nonclinical staff (relative risk, 0.98; 95% confidence interval, 0.78-1.20). Reported community exposure to pH1N1 was common and was similar in both groups.

Virological and clinical characterization of respiratory infections in children attending an emergency department during the first autumn-winter circulation of pandemic A (H1N1) 2009 influenza virus

To characterize respiratory virus infections during the first autumn-winter season of pandemic A (H1N1) 2009 influenza virus (A/H1N1/2009) circulation, a prospective study in children attending a paediatric emergency department at the Sapienza University hospital, Rome, was conducted from November 2009 to March 2010. By means of both nasal washings and pharyngeal swabs, enrolled children were checked for 14 respiratory viruses. The majority of acute respiratory infections resulted from viral pathogens (135/231, 58%). Overall, the most common was respiratory syncytial virus (RSV), in 64% of positive samples; A/H1N1/2009 was the only influenza virus found in 16% and rhinovirus (RV) in 15%. Virus-positive children did not differ significantly from virus-negative children in signs and symptoms at presentation; of the virus groups, RSV-infected children were younger and more frequently admitted to intensive-care units than those infected with A/H1N1/2009 and RV. Of the hospitalized children, stratified by age, both infants and children aged >1 year with RSV were most severely affected, whereas A/H1N1/2009 infections were the mildest overall, although with related pulmonary involvement in older children. Children with RV infections, detected in two flares partially overlapping with the A/H1N1/2009 and RSV peaks, presented with bronchiolitis, wheezing and pneumonia. Leukocytosis occurred more frequently in RV-infected and A/H1N1/2009-infected children, and numbers of blood eosinophils were significantly elevated in RV-infected infants. Given the fact that clinical and epidemiological criteria are not sufficient to identify viral respiratory infections, a timely virological diagnosis could allow different infections to be managed separately.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Changing epidemiology of respiratory viral infections in hematopoietic cell transplant recipients and solid organ transplant recipients

PURPOSE OF REVIEW

New respiratory viruses have been discovered in recent years and new molecular diagnostic assays have been developed that improve our understanding of respiratory virus infections. This article will review the changing epidemiology of these viruses after hematopoietic stem cell and solid organ transplantation.

RECENT FINDINGS

Respiratory viruses are frequently detected in transplant recipients. A number of viruses have been newly discovered or emerged in the last decade, including human metapneumovirus, human bocavirus, new human coronaviruses and rhinoviruses, human polyomaviruses, and a new 2009 pandemic strain of influenza A/H1N1. The potential for these viruses to cause lower respiratory tract infections after transplantation varies, and is greatest for human metapneumovirus and H1N1 influenza, but appears to be limited for the other new viruses. Acute and long-term complications in hematopoietic and solid organ transplant recipients are active areas of research.

SUMMARY

Respiratory viral infections are frequently associated with significant morbidity following transplantation and are therefore of great clinical and epidemiologic interest. As new viruses are discovered, and more sensitive diagnostic methods are developed, defining the full impact of emerging respiratory viruses in transplant recipients must be elucidated by well designed clinical studies.

Comparison of characteristics of outpatients with 2009 H1N1 pandemic and seasonal influenza

BACKGROUND

The latest influenza pandemic intensified the interest in this infection.

OBJECTIVE

We aimed to compare the characteristics of outpatients with seasonal and pandemic influenza.

METHODS

We retrospectively reviewed data regarding outpatients who sought medical advice from a network of physicians performing house-call visits at the area of Attica, Greece, and who underwent a direct influenza test during the period of seasonal influenza (1/1/2009-1/5/2009) and 2009 H1N1 pandemic influenza period (17/5/2009-15/4/2010).

RESULTS

A total of 195 and 1317 patients had a direct influenza test during the seasonal and pandemic influenza period, respectively; 50.7% and 32% of these patients had a positive test result for influenza, respectively. Viral culture or polymerase chain reaction (PCR) were not implemented. Patients found positive for influenza during the pandemic period, compared with those evaluated during the seasonal period, were younger (mean age ± SD: 33 ± 17.2 vs. 38.2 ± 19.2, p = 0.008), more likely to have no comorbidity (62.9% vs. 45.5%, p = 0.002), had milder clinical manifestations, and were treated with more antibiotics (38.3% vs. 9.9%, p < 0.001). However, patients found positive during the seasonal period were treated with more antivirals (oseltamivir: 69.1% vs. 85.7%, p = 0.006). No difference was observed regarding the need for immediate hospitalisation. These findings were consistent in the complementary analysis involving patients tested for influenza during the compared periods.

CONCLUSION

Despite the methodological limitations, our findings suggest that patients with pandemic influenza were younger, had milder clinical manifestations and were less likely to have any kind of comorbidity compared with patients with seasonal influenza.

Complications and outcomes of pandemic 2009 Influenza A (H1N1) virus infection in hospitalized adults: how do they differ from those in seasonal influenza?

BACKGROUND

It is unclear whether pandemic 2009 influenza A (pH1N1) infection caused more significant disease among hospitalized adults than seasonal influenza.

METHODS

A prospective, observational study was conducted in adults hospitalized with polymerase chain reaction-confirmed pH1N1 infection in 2 acute-care general hospitals from June 2009 to May 2010 (n = 382). Complications and outcomes were described and compared with those in a seasonal influenza cohort (2007-2008, same hospitals; n = 754).

RESULTS

Hospitalized patients with pH1N1 influenza were younger than those with seasonal influenza (mean age ± standard deviation, 47 ± 20 vs 70 ± 19 years) and fewer had comorbid conditions (48% vs 64%). The rate of positive immunofluorescence assay results was low (54% vs 84%), and antiviral use was frequent (96% vs 52%). Most patients in both cohorts developed complicated illnesses (67.8% vs 77.1%), but patients with pH1N1 influenza had higher rates of extrapulmonary complications (23% vs 16%; P = .004) and intensive care unit admission and/or death (patient age <35 years, 2.3% vs 0%; 35-65 years, 12.4% vs 3.2%; >65 years, 13.5% vs 8.5%; adjusted odds ratio [OR] 2.13; 95% confidence interval [CI], 1.25-3.62; P = .005). Patients who received antiviral treatment within 96 h after onset had better survival (log-rank test, P < .001). However, without timely treatment, the mortality risk was higher with pH1N1 infection (9.0% vs 5.8% for seasonal influenza; adjusted OR, 6.85; 95% CI, 1.64-28.65; P = .008]. Bacterial superinfection worsened outcomes.

CONCLUSIONS

Adults hospitalized for pH1N1 influenza had significant complications and mortality despite being younger than patients with seasonal influenza. Antiviral treatment within 96 h may improve survival.

2009 pandemic influenza A (H1N1) in pregnancy: a systematic review of the literature

To summarize the literature regarding 2009 H1N1 influenza A during pregnancy, we conducted a systematic literature review using a PubMed search and other strategies. Studies were included if they reported 2009 H1N1 influenza in pregnant women as original data. In all, 2153 abstracts were reviewed, and a total of 120 studies were included. Data were extracted regarding number of cases, additional risk factors for influenza-associated complications, treatment, and maternal and pregnancy outcomes. Authors were contacted to determine the extent of overlap when it was suspected. Pregnancy was associated with increased risk of hospital and intensive care unit admission and of death. Pregnant women who received delayed treatment with neuraminidase inhibitors or who had additional risk factors were more likely to develop severe disease. Preterm and emergency cesarean deliveries were frequently reported. These results reinforce the importance of early identification and treatment of suspected influenza in this high-risk population.

Emerging oseltamivir resistance in seasonal and pandemic influenza A/H1N1

The emergence of oseltamivir resistance in seasonal and pandemic influenza A/H1N1 has created challenges for diagnosis and clinical management. This review discusses how clinical virology laboratories have handled diagnosis of oseltamivir-resistant H1N1 and what we have learned from clinical studies and case series. Immunocompetent patients infected with oseltamivir-resistant H1N1 have similar outcomes as patients infected with oseltamivir-susceptible H1N1. However, immunocompromised patients infected with oseltamivir-resistant H1N1 experience potentially more risks of complication and transmissibility with few therapeutic options.

Differences in clinical outcomes after 2009 influenza A/H1N1 and seasonal influenza among hematopoietic cell transplant recipients

It is not known whether pandemic 2009 influenza A/H1N1 (2009 H1N1) leads to more serious disease than seasonal influenza in hematopoietic cell transplant (HCT) recipients. In a retrospective study in HCT recipients with virologically proven influenza virus infection, a total of 161 HCT recipients (18 2009 H1N1, 103 seasonal influenza A, and 40 seasonal influenza B) were analyzed. In multivariable analyses, more patients with 2009 H1N1 had lower respiratory tract disease (LRD), hypoxemia, and prolonged viral shedding compared with seasonal influenza A. Seasonal influenza A and B outcomes were similar. There was no difference in overall and influenza-associated mortality among influenza virus types. Both early and delayed administration of antiviral therapy was shown to be beneficial in terms of decreased rates of development of LRD, although earlier intervention appeared to be more effective. Profound lymphopenia and lack of early antiviral therapy were associated significantly with LRD, hypoxemia, and death. High-dose corticosteroid treatment (≥ 1 mg/kg) given at the time of influenza diagnosis was associated with a reduced risk for mechanical ventilation. Thus, our data suggest that infection with 2009 influenza A/H1N1 resulted in more severe respiratory disease in HCT recipients compared with seasonal influenza.

Convalescent plasma treatment reduced mortality in patients with severe pandemic influenza A (H1N1) 2009 virus infection

Background. Experience from treating patients with Spanish influenza and influenza A(H5N1) suggested that convalescent plasma therapy might be beneficial. However, its efficacy in patients with severe pandemic influenza A(H1N1) 2009 virus (H1N1 2009) infection remained unknown.

Methods. During the period from 1 September 2009 through 30 June 2010, we conducted a prospective cohort study by recruiting patients aged ≥18 years with severe H1N1 2009 infection requiring intensive care. Patients were offered treatment with convalescent plasma with a neutralizing antibody titer of ≥1:160, harvested by apheresis from patients recovering from H1N1 2009 infection. Clinical outcome was compared with that of patients who declined plasma treatment as the untreated controls.

Results. Ninety-three patients with severe H1N1 2009 infection requiring intensive care were recruited. Twenty patients (21.5%) received plasma treatment. The treatment and control groups were matched by age, sex, and disease severity scores. Mortality in the treatment group was significantly lower than in the nontreatment group (20.0% vs 54.8%; P =  .01). Multivariate analysis showed that plasma treatment reduced mortality (odds ratio [OR], .20; 95% confidence interval [CI], .06-.69; P =  .011), whereas complication of acute renal failure was independently associated with death (OR, 3.79; 95% CI, 1.15-12.4; P =  .028). Subgroup analysis of 44 patients with serial respiratory tract viral load and cytokine level demonstrated that plasma treatment was associated with significantly lower day 3, 5, and 7 viral load, compared with the control group (P <  .05). The corresponding temporal levels of interleukin 6, interleukin 10, and tumor necrosis factor α (P <  .05) were also lower in the treatment group.

Conclusions. Treatment of severe H1N1 2009 infection with convalescent plasma reduced respiratory tract viral load, serum cytokine response, and mortality.

A comparison of the epidemiology and clinical presentation of seasonal influenza A and 2009 pandemic influenza A (H1N1) in Guatemala

BACKGROUND

A new influenza A (H1N1) virus was first found in April 2009 and proceeded to cause a global pandemic. We compare the epidemiology and clinical presentation of seasonal influenza A (H1N1 and H3N2) and 2009 pandemic influenza A (H1N1) (pH1N1) using a prospective surveillance system for acute respiratory disease in Guatemala.

METHODOLOGY/FINDINGS

Patients admitted to two public hospitals in Guatemala in 2008-2009 who met a pneumonia case definition, and ambulatory patients with influenza-like illness (ILI) at 10 ambulatory clinics were invited to participate. Data were collected through patient interview, chart abstraction and standardized physical and radiological exams. Nasopharyngeal swabs were taken from all enrolled patients for laboratory diagnosis of influenza A virus infection with real-time reverse transcription polymerase chain reaction. We identified 1,744 eligible, hospitalized pneumonia patients, enrolled 1,666 (96%) and tested samples from 1,601 (96%); 138 (9%) had influenza A virus infection. Surveillance for ILI found 899 eligible patients, enrolled 801 (89%) and tested samples from 793 (99%); influenza A virus infection was identified in 246 (31%). The age distribution of hospitalized pneumonia patients was similar between seasonal H1N1 and pH1N1 (P = 0.21); the proportion of pneumonia patients <1 year old with seasonal H1N1 (39%) and pH1N1 (37%) were similar (P = 0.42). The clinical presentation of pH1N1 and seasonal influenza A was similar for both hospitalized pneumonia and ILI patients. Although signs of severity (admission to an intensive care unit, mechanical ventilation and death) were higher among cases of pH1N1 than seasonal H1N1, none of the differences was statistically significant.

CONCLUSIONS/SIGNIFICANCE

Small sample sizes may limit the power of this study to find significant differences between seasonal influenza A and pH1N1. In Guatemala, influenza, whether seasonal or pH1N1, appears to cause severe disease mainly in infants; targeted vaccination of children should be considered.