Influenza-associated Severe Acute Respiratory Infection Research Articles

Incidence of Hospitalization due to Influenza-Associated Severe Acute Respiratory Infection During 2010-2019 in Bangladesh.

Global influenza-associated acute respiratory infections contribute to 3-5 million severe illnesses requiring hospitalization annually, with 90% of hospitalizations occurring among children < 5 years in developing countries. In Bangladesh, the inadequate availability of nationally representative, robust estimates of influenza-associated hospitalizations limits allocation of resources for prevention and control measures. This study used data from the hospital-based influenza surveillance (HBIS) system in Bangladesh from 2010 to 2019 and healthcare utilization surveys to determine hospital utilization patterns in the catchment area. We estimated annual influenza-associated hospitalization numbers and rates for all age groups in Bangladesh using WHO methods, adjusted for a 6-day-a-week enrollment schedule, selective testing of specimens from children under five, and healthcare-seeking behavior, based on the proportion of symptomatic community participants seeking healthcare within the past week. We then estimated national hospitalization rates by multiplying age-specific hospitalization rates with the corresponding annual national census population. Annual influenza-associated hospitalization rates per 100,000 population for all ages ranged from 31 (95% CI: 27-36) in 2011 to 139 (95% CI: 130-149) in 2019. Children < 5 years old had the highest rates of influenza-associated hospitalization, ranging from 114 (95% CI: 90-138) in 2011 to 529 (95% CI: 481-578) in 2019, followed by adults aged ≥ 65 years with rates ranging from 46 (95% CI: 34-57) in 2012 to 252 (95% CI: 213-292) in 2019. The national hospitalization estimates for all ages during 2010-2019 ranged from 47,891 to 236,380 per year. The impact of influenza-associated hospitalizations in Bangladesh may be considerable, particularly for young children and older adults. Targeted interventions, such as influenza vaccination for these age groups, should be prioritized and evaluated.

Influenza-associated severe acute respiratory infections among children under five years old in Morocco, September 2017 to March 2019.

The main aim of this research is to investigate the trend of influenza infection among children under 5 years with severe acute respiratory infections (SARI) as well as those who suffer from a high burden of disease. This research is based on a survey conducted from September 2017 to March 2019. During this period nasopharyngeal swabs were collected in a group of 942 children under 5 years with SARI, admitted in pediatric services of 8 sentinel hospitals. The virological surveillance of influenza was carried out at the National influenza Center, located in the National Institute of Hygiene, using a Reverse transcription polymerase chain reaction (qRt-PCR) monoplex assay developed by the Centers for Disease Control and Prevention (CDC; Atlanta, GA). The median age of participants was 11 months, and 40% of them were female. A total of 112 samples were reported positive yielding a frequency of 11.88% (112/942). Among all the influenza confirmed cases, 68.75% (77/112), 15.17% (17/112), 16.04% (18/112) were subtyped as influenza AH1N1pdm09, AH3N2 and influenza B respectively. Meanwhile, the proportion of patients admitted at the intensive care unit was 5,35% (6/112). Out of which 83.33% (5/6) were AH1N1pdm09 and it was reported that just 1.78% (2/112) of the positive cases were vaccinated. The study confirms that influenza affects greatly children with SARI. Thus, the need for influenza vaccines is highly recommended for children under 5 years. Moreover, our findings highlight that influenza virus is not the only cause of SARI among this group of children. Accordingly, special attention should be paid to the non-flu respiratory viruses.

Sleep Apnea and Risk of Influenza-Associated Severe Acute Respiratory Infection: Real-World Evidence.

PurposeWe executed the presented retrospective cohort study with the purpose of probing the risk of severe acute respiratory infection (SARI) following influenza in patients with sleep apnea.Materials and MethodsWe executed this real-world study by gathering Taiwan National Health Insurance Research Database (NHIRD) data. From a database containing 1 million individuals sampled at random from the NHIRD, we identified all patients aged 20 years or older with a sleep apnea diagnosis between 1997 and 2013 as the study group. We established a comparison cohort of individuals without sleep apnea by randomly matching patients with respect to monthly income, gender, urbanization level, and age at a 1:4 ratio. Follow-up was performed until death or the end of 2015 for both groups. We determined the study outcome to be the occurrence of influenza-associated SARI.ResultsWe enrolled 6508 and 26,032 patients into the study and comparison groups, respectively. A significantly higher cumulative incidence of influenza-associated SARI was discovered in the study group (p < 0.001). In our multivariate analysis, sleep apnea, chronic obstructive pulmonary disease, and coronary artery disease were independent risk factors for influenza-associated SARI. The hazard ratio of sleep apnea for influenza-associated SARI was 1.98 (95% CI: 1.26–3.10) after adjustment for all comorbidities, gender, age, monthly income, and urbanization level.ConclusionSleep apnea increased the risk of influenza-associated SARI. We suggest that physicians be cautious about the development of severe influenza illness in patients with sleep apnea. Vaccination and early oseltamivir administration should be actively considered in this group of patients.

Influenza circulating viruses, positivity rate and risk factors for influenza associated severe acute respiratory infection during 2018/2019 winter season, Yemen

BackgroundThe burden of seasonal influenza in conflict counties is exacerbated due to limited resource and collapse of health system. During 2018 /2019 season, two-fold increase in the incidence of influenza was reported in Yemen with 22% case fatality of severe acute respiratory infection (SARI). The aims are to analyze the influenza circulating viruses, positivity rate and risk factors for hospitalizing influenza associated-SARI.MethodologyWe used a retrospective analytical study based on surveillance data. All reported patients during 2018/2019 season, fulfilling the WHO cases definition for SARI or influenza like illness (ILI), and had laboratory result from the National Laboratory were included. Influenza positivity rate was calculated, all SARI and ILI patients with positive influenza were included for further analysis by univariate and multivariate binary logistic regression. Crude and adjusted Odds ratio (AOR), 95% confidence interval and P-value < 0.05 were used for statistically significant.ResultsOut of 2186 patients enrolled, 768 patients were tested for influenza viruses,: 19% were children < 15 years, 15% were ≥ 65 years, 69% males and 18% had co-morbidity with chronic diseases. Patients with SARI were 37% and 63% were ILI patients. Influenza viruses were detected in 411 (53.5%), 68% were influenza A subtype (H1N1)pdm09, 27% influenza B and 5% was influenza A not subtyped. The influenza positivity was significantly higher in SARI compared to ILI for patients < 15 years (95% vs, 66%, p < 0.001), and patients ≥ 65 years (83% vs. 56%, p < 0.002), respectively. The highest positivity for influenza type A and B reached 44% and 33% for patients ≥ 65 years and < 15 years, respectively. The risk factors for influenza-associated SARI in multivariate analysis included age < 5 [AOR 2.8] and ≥ 65 years old [AOR 3.1] compared to age 5– < 25 years, diabetes [AOR 4.7], heart diseases [AOR 3.1] and chronic respiratory diseases [AOR 5.0].ConclusionThe influenza positivity during 2018/2019 winter season was high in Yemen and varied by age distribution. Influenza subtype A (H1N1) pdm09 was the predominant and co circulated with influenza B. An influenza vaccination program for the risk group is necessary. Strengthening lab capacity to detect respiratory pathogens and further prospective study for more comprehensive picture are recommended.

Burden of Influenza-Associated Respiratory Hospitalizations, Vietnam, 2014-2016.

Influenza burden estimates are essential to informing prevention and control policies. To complement recent influenza vaccine production capacity in Vietnam, we used acute respiratory infection (ARI) hospitalization data, severe acute respiratory infection (SARI) surveillance data, and provincial population data from 4 provinces representing Vietnam’s major regions during 2014–2016 to calculate provincial and national influenza-associated ARI and SARI hospitalization rates. We determined the proportion of ARI admissions meeting the World Health Organization SARI case definition through medical record review. The mean influenza-associated hospitalization rates per 100,000 population were 218 (95% uncertainty interval [UI] 197–238) for ARI and 134 (95% UI 119–149) for SARI. Influenza-associated SARI hospitalization rates per 100,000 population were highest among children <5 years of age (1,123; 95% UI 946–1,301) and adults >65 years of age (207; 95% UI 186–227), underscoring the need for prevention and control measures, such as vaccination, in these at-risk populations.

Cost-effectiveness analysis of quadrivalent influenza vaccination for older adults aged 60 and above in mainland China

Objective: To evaluate the cost-effectiveness of government fully-funded quadrivalent influenza vaccination (QIV) program for older adults aged 60 and above in mainland China. Methods: Based on decision tree model in the previous research on the cost-effectiveness analysis of TIV immunization, we extended the structure of model and updated the key parameters such as influenza patients' healthcare seeking behavior, vaccine cost, vaccine coverage and vaccine efficacy/effectiveness to estimate influenza-associated outpatient consultations, hospitalizations, respiratory disease excess mortality and quality-adjusted life years (QALY) between the QIV and no vaccination or TIV program. And incremental cost and incremental cost-effectiveness ratio (ICER) were evaluated between the QIV and no vaccination or TIV program from the societal perspective. The time frame of the study is one year. All costs were adjusted to 2019 using the consumer price index. Results: Comparing the fully-funded QIV and no vaccination or TIV for older adults aged 60 and above is separately expected to prevent 45 070 or 2 718 influenza-associated influenza-like illness (ILI) outpatients, 21 451 or 1 294 influenza-associated severe acute respiratory infection (SARI) hospitalizations, 19 346 or 1 167 influenza-associated respiratory excess deaths and avoid 155 234 or 9 363 QALY loss each year. Compared with no vaccination, introducing QIV into National Immunization Program (NIP) is expected to increase the cost of 11.71 billion yuan from the societal perspective. The incremental cost per QALY gained between QIV and no vaccination was 75 325 yuan per QALY, which is higher than willingness-to-pay (WTP) threshold (one-fold gross domestic product per capita is considered as WTP: 70 892 yuan) and means no cost effective. Introducing QIV rather than TIV into NIP will cost 7.98 billion yuan from the societal perspective and the ICER was 852.54 thousand yuan per QALY which is much higher than WTP and means no cost effective as well. The threshold of vaccination cost between QIV and no vaccination or TIV should no more than 113.41 or 6.83 yuan when the two comparators' scenarios above are all cost effective. Conclusion: Under the condition of current vaccine effectiveness and vaccine cost, comparing fully-funded QIV with no or TIV vaccination program is not cost effective for people aged 60 years or older.

Influenza epidemiology and burden of disease in Mongolia, 2013–2014 to 2017–2018

Background: Mongolia is a vast, sparsely populated country in central Asia. Its harsh climate and nomadic lifestyle make the population vulnerable to acute respiratory infections, particularly influenza. Evidence on the morbidity, mortality and socioeconomic impact of influenza in Mongolia is scarce; however, routine surveillance for influenza-like illness (ILI), severe acute respiratory infection (SARI) and laboratory-detected influenza is conducted. This paper describes the epidemiology of influenza and the estimated burden of influenza-associated illness in Mongolia in the five influenza seasons between 2013–2014 and 2017–2018. Methods: Demographic and laboratory data from 152 sentinel surveillance sites on all patients who met the case definitions of ILI and SARI between October 2013 and May 2018 were extracted and analysed as described in A Manual for Estimating Disease Burden Associated with Seasonal Influenza. Results: The estimated annual influenza-associated ILI and SARI rates, presented as ranges, were 1279–2798 and 81–666 cases per 100 000 population, respectively. Children aged &lt;5 years accounted for 67% of all ILI cases and 79% of all SARI cases. The annual specimen positivity for influenza was highest (11–30% for ILI and 8–31% for SARI) for children aged 5–&lt;15 years and children &lt;2 years old, respectively. The annual mortality rate due to pneumonia and SARI was highest among children aged &lt;2 years (15.8–54.0 per 100 000 population). Although the incidence of influenza-associated ILI and SARI was lowest for people aged &gt;65 years, the mortality rate due to pneumonia and SARI (1.2–5.1 per 100 000) was higher than that for those aged 15–64 years. Conclusion: The estimated influenza-associated ILI and SARI incidence rates are high in Mongolia, and children, especially those aged &lt;5 years, have the highest influenza-associated burden in Mongolia. These findings provide evidence for decision-makers in Mongolia to consider targeted influenza vaccination, particularly for children.

Estimating the national burden of hospitalizations for influenza-associated severe acute respiratory infection in the Lao People's Democratic Republic, 2016.

ObjectiveEstimates of the burden of influenza are needed to inform prevention and control activities for seasonal influenza, including to support the development of appropriate vaccination policies. We used sentinel surveillance data on severe acute respiratory infection (SARI) to estimate the burden of influenza-associated hospitalizations in the Lao People's Democratic Republic.MethodsUsing methods developed by the World Health Organization, we combined data from hospital logbook reviews with epidemiological and virological data from influenza surveillance from 1 January to 31 December 2016 in defined catchment areas for two sentinel sites (Champasack and Luang Prabang provincial hospitals) to derive population-based estimates of influenza-associated SARI hospitalization rates. Hospitalization rates by age group were then applied to national age-specific population estimates using 2015 census data.ResultsWe estimated the overall influenza-associated SARI hospitalization rate to be 48/100 000 population (95% confidence interval [CI]: 44–51) or 3097 admissions (95% CI: 2881–3313). SARI hospitalization rates were estimated to be as low as 40/100 000 population (95% CI: 37–43) and as high as 92/100 000 population (95% CI: 87–98) after accounting for SARI patient underascertainment in hospital logbooks. Influenza-associated SARI hospitalization rates were highest in children aged < 5 years (219; 95% CI: 198–241) and persons aged 3 65 years (106; 95% CI: 91–121).DiscussionOur findings have identified age groups at higher risk for influenza-associated SARI hospitalization, which will support policy decisions for influenza prevention and control strategies, including for vaccination. Further work is needed to estimate the burdens of outpatient influenza and influenza in specific high-risk subpopulations.

Influenza epidemiology and burden of disease in Mongolia, 2013-2014 to 2017-2018.

BackgroundMongolia is a vast, sparsely populated country in central Asia. Its harsh climate and nomadic lifestyle make the population vulnerable to acute respiratory infections, particularly influenza. Evidence on the morbidity, mortality and socioeconomic impact of influenza in Mongolia is scarce; however, routine surveillance for influenza-like illness (ILI), severe acute respiratory infection (SARI) and laboratory-detected influenza is conducted. This paper describes the epidemiology of influenza and the estimated burden of influenza-associated illness in Mongolia in the five influenza seasons between 2013–2014 and 2017–2018.MethodsDemographic and laboratory data from 152 sentinel surveillance sites on all patients who met the case definitions of ILI and SARI between October 2013 and May 2018 were extracted and analysed as described in A Manual for Estimating Disease Burden Associated with Seasonal Influenza.ResultsThe estimated annual influenza-associated ILI and SARI rates, presented as ranges, were 1279–2798 and 81–666 cases per 100 000 population, respectively. Children aged < 5 years accounted for 67% of all ILI cases and 79% of all SARI cases. The annual specimen positivity for influenza was highest (11–30% for ILI and 8–31% for SARI) for children aged 5– < 15 years and children < 2 years old, respectively. The annual mortality rate due to pneumonia and SARI was highest among children aged < 2 years (15.8–54.0 per 100 000 population). Although the incidence of influenza-associated ILI and SARI was lowest for people aged 365 years, the mortality rate due to pneumonia and SARI (1.2–5.1 per 100 000) was higher than that for those aged 15–64 years.ConclusionThe estimated influenza-associated ILI and SARI incidence rates are high in Mongolia, and children, especially those aged < 5 years, have the highest influenza-associated burden in Mongolia. These findings provide evidence for decision-makers in Mongolia to consider targeted influenza vaccination, particularly for children.

Influenza Vaccine Effectiveness for Prevention of Severe Influenza-Associated Illness Among Adults in the United States, 2019-2020: A Test-Negative Study.

Influenza vaccine effectiveness (VE) against a spectrum of severe disease, including critical illness and death, remains poorly characterized. We conducted a test-negative study in an intensive care unit (ICU) network at 10 US hospitals to evaluate VE for preventing influenza-associated severe acute respiratory infection (SARI) during the 2019-2020 season, which was characterized by circulation of drifted A/H1N1 and B-lineage viruses. Cases were adults hospitalized in the ICU and a targeted number outside the ICU (to capture a spectrum of severity) with laboratory-confirmed, influenza-associated SARI. Test-negative controls were frequency-matched based on hospital, timing of admission, and care location (ICU vs non-ICU). Estimates were adjusted for age, comorbidities, and other confounders. Among 638 patients, the median (interquartile) age was 57 (44-68) years; 286 (44.8%) patients were treated in the ICU and 42 (6.6%) died during hospitalization. Forty-five percent of cases and 61% of controls were vaccinated, which resulted in an overall VE of 32% (95% CI: 2-53%), including 28% (-9% to 52%) against influenza A and 52% (13-74%) against influenza B. VE was higher in adults 18-49 years old (62%; 95% CI: 27-81%) than those aged 50-64 years (20%; -48% to 57%) and ≥65 years old (-3%; 95% CI: -97% to 46%) (P = .0789 for interaction). VE was significantly higher against influenza-associated death (80%; 95% CI: 4-96%) than nonfatal influenza illness. During a season with drifted viruses, vaccination reduced severe influenza-associated illness among adults by 32%. VE was high among young adults.

Estimating the disease burden of seasonal influenza in China, 2006-2019

Objective: To estimate the health impact and economic burden of seasonal influenza in mainland China. Methods: From systematic literature reviews, we collected the influenza-associated excess influenza-like-illness (ILI) outpatient consultation rates, hospitalization rates of severe acute respiratory infections (SARI) and respiratory excess mortality, 2006-2017. Using these data, as well as demographic data (2019), the number of influenza-associated excess ILI outpatient consultations, SARI hospitalizations and respiratory excess deaths were estimated. Then using per capita economic burden of influenza-associated outpatient consultations and hospitalizations, as well as the productivity loss of influenza-related premature deaths, the annual influenza-associated total economic burden was estimated. All costs were adjusted to 2019 using the consumer price index. Results: The annual influenza-associated excess ILI outpatient consultations, SARI hospitalizations and excess respiratory deaths were 3 million, 2.34 million, 0.09 million, respectively. The total economic burden was 26.38 billion CNY, accounting for 0.266‰ GDP in 2019, of which the hospitalization-related economic burden accounted for the highest proportion (86.4%, 22.79 billion CNY), followed by the outpatient-related economic burden (11.3%, 2.97 billion CNY), and the indirect economic burden of productivity loss of premature deaths was the lowest (2.4%, 0.62 billion CNY). Largest economic burden was observed in East China (10.51 billion CNY) and smallest observed in Northeast China (0.38 billion CNY). Conclusion: The health burden of influenza-related outpatient visits and hospitalizations were substantial. The economic burden of influenza-related SARI hospitalization was higher than that of influenza-related outpatients and pre-mature deaths. The highest economic burden of influenza occurred in the East China.

Influenza epidemiology and risk factors for severe acute respiratory infection in Morocco during the 2016/2017 and 2017/2018 seasons.

Introductionin order to implement an influenza vaccination program for high-risk-groups in Morocco, as recommended by the World Health Organization, an epidemiological study indicating the influenza virus effect in the development of complicated influenza for subjects with co-morbidity was required. The present study aims to evaluate the risk factors for severe acute respiratory infections caused by influenza in risk groups.Methodsthis research is based on the epidemiological and virological surveillance data of severe acute respiratory infections and influenza-like illness during the 2016/2017 and 2017/2018 seasons. It was realized using a retrospective series study with a descriptive and analytical purpose.Resultsthe over-recruitment of pediatric cases with a severe acute respiratory infection has been significantly rectified because cases of severe acute respiratory infections under 15 years old in the 2017/2018 season represent only 57.9%, whereas they represented 75.9% of the total cases of severe acute respiratory infections during the 2016/2017 season. The influenza positivity rate has increased globally and specifically by age group, clinical service and co-morbidity. The risk factors considered were significantly associated with hospitalization for influenza-associated severe acute respiratory infections. The multivariate logistic regression analysis considers male sex (OR=2.1), age ≥65 years (OR=5.4), presence of influenza cases in the surroundings (OR=0.1), diabetes (OR=7.5) and chronic respiratory disease (OR=10.9) as risk factors influenza-associated severe acute respiratory infections.Conclusionthe risk assessment of influenza-associated severe acute respiratory infections in high-risk groups revealed national epidemiological findings, particularly for diabetics and the elderly. An influenza vaccination program for these high-risk-groups becomes much recommended in Morocco.

Influenza-associated Hospitalization in Children Younger Than 5 Years of Age in Suzhou, China, 2011-2016.

Studying the burden and risk factors associated with severe illness from influenza infection in young children in eastern China will contribute to future cost-effectiveness analyses of local influenza vaccine programs. We conducted prospective, severe acute respiratory infection (SARI) surveillance at Suzhou University-Affiliated Children's Hospital to estimate influenza-associated hospitalizations in Suzhou University-Affiliated Children's Hospital by month in children younger than 5 years of age from October 2011 to September 2016. SARI was defined as fever (measured axillary temperature ≥ 38°C) and cough or sore throat or inflamed/red pharynx in the 7 days preceding hospitalization. We combined SARI surveillance data with healthcare utilization survey data to estimate and characterize the burden of influenza-associated SARI hospitalizations in Suzhou within this age group in the 5-year period. Of the 36,313 SARI cases identified, 2,297 from respiratory wards were systematically sampled; of these, 259 (11%) were influenza positive. Estimated annual influenza-associated SARI hospitalization rates per 1,000 children younger than 5 years of age ranged from 4 (95% confidence interval [CI], 2-5) in the 2012-2013 season to 16 (95% CI, 14-19) in the 2011-2012 season. The predominant viruses were A/H3N2 (59%) in 2011-12, both A/H1N1pdm09 (42%) and B (46%) in 2012-13, A/H3N2 (71%) in 2013-14, A/H3N2 (55%) in 2014-15 and both A/H1N1pdm09 (50%) and B (50%) in 2015-16. The age-specific influenza-associated SARI hospitalization rates for the 5-year period were 11 (95% CI, 8-15) per 1,000 children 0-5 months of age; 8 (95% CI, 7-10) per 1,000 children 6-23 months of age and 5 (95% CI, 4-5) per 1,000 children 24-59 months of age, respectively. From 2011 to 2016, influenza-associated SARI hospitalization rates in children aged younger than 5 years of age in Suzhou, China, were high, particularly among children 0-5 months of age. Higher hospitalization rates were observed in years where the predominant circulating virus was influenza A/H3N2. Immunization for children > 6 months, and maternal and caregiver immunization for those < 6 months, could reduce influenza-associated hospitalizations in young children in Suzhou.

CHARACTERISTICS OF INFLUENZA INFECTION IN 2017 AND CURRENT PRACTICE: A RETROSPECTIVE STUDY AT A COLLEGE HOSPITAL IN JEDDAH

Saudi Arabia has recentlystarted a surveillance process for seasonal influenza outbreaks. Special interest should be given to the influenza-associated severe acute respiratory infection (SARI) to describe the epidemiological and clinical characteristics and current practice of influenza-associated SARI in 2017. A retrospective observational study was conducted at IbnSina National College Hospital in Jeddah in 2018. Review of medical records was done using checklists for in-patients who did rapid influenza diagnostic tests during 2017 using nasopharyngeal swabs and for whom coronavirus RT-PCR test was also performed by the “Saudi National Health Laboratory”. Data collection included time of admission, demographic, clinical, and laboratory data, treatment, and outcome. Among 300 in-patients with fever, 31.3% had SARI due to influenza A rather than B but not H1N1 or MERS-CoV infection. SARI cases clustered during July and September (‘Ramadan’ and ‘Hajj’ periods). The risk of flu-related complications was high (45.7%) and included mostly children &lt; 5 and presented mainly with pneumonia (21.3%). The main presentations were fever (83%), flu-like symptoms (41.9%), nonproductive cough (33%), dyspnea (25%), vomiting (14.9%), and abdominal pain (8.5%). Patients had lymphocytosis (27.7%) and neutropenia (20.2%).All received antiviral oseltamivir (16% received it late, 3.4% did not continue after discharge) and 90.4% received empirical antibiotics. All recovered completely with no ICU admission. Seasonal influenza A-associated SARI in 2017 in our hospital coincided with ‘Ramadan’ and ‘Hajj’ periods, presented with typical symptoms, and had a high risk of complications, especially pneumonia. It was amenable to antiviral therapy with a favorable outcome. Most patients received empirical antibiotics and a few did not receive proper antiviral therapy. Physicians should consider early antiviral treatment in patients with suspected SARI during influenza seasons. There is a need for national recommendations to guide antibiotic strategies and regimens in influenza-associated SARI.

Severe acute respiratory infections (SARI) from influenza in adult patients in Chile: the experience of a sentinel hospital.

ABSTRACTObjectiveTo 1) describe clinical characteristics of adult patients in Chile with severe acute respiratory infections (SARI) associated with influenza viruses, and 2) analyze virus subtypes identified in specimens collected from those patients, hospital resources used in clinical management, clinical evolution, and risk factors associated with a fatal outcome, using observational data from the SARI surveillance network (SARInet).MethodsAdults hospitalized from 1 July 2011 to 31 December 2015 with influenza-associated SARI at a SARI sentinel surveillance hospital in Santiago were identified and the presence of influenza in all cases confirmed by reverse transcription polymerase chain reaction (RT-PCR), using respiratory samples.ResultsA total of 221 patients (mean age: 74.1 years) were hospitalized with influenza-associated SARI during the study period. Of this study cohort, 91.4% had risk factors for complications and 34.3% had been vaccinated during the most recent campaign. Pneumonia was the most frequent clinical manifestation, occurring in 57.0% of the cohort; other manifestations included influenza-like illness, exacerbated chronic bronchitis, decompensated heart failure, and asthmatic crisis. Cases occurred year-round, with an epidemic peak during autumn–winter. Both influenza A (H1N1pdm09 and H3N2) and B virus co-circulated. Critical care beds were required for 26.7% of the cohort, and 19.5% needed ventilatory assistance. Multivariate analysis identified four significant factors associated with in-hospital mortality: 1) being bedridden (adjusted odds ratio (aOR): 22.3; 95% confidence interval (CI): 3.0–164); 2) admission to critical care unit (aOR: 8.9; CI: 1.44–55); 3) Pa02/Fi02 ratio < 250 (aOR: 5.8; CI: 1.02–33); and 4) increased serum creatinine concentration (> 1 mg/dL) (aOR: 5.47; CI: 1.20–24). Seasonal influenza vaccine was identified as a significant protective factor (aOR: 0.14; CI: 0.021–0.90).ConclusionsInfluenza-associated SARI affected mainly elderly patients with underlying conditions. Most patients evolved to respiratory failure and more than one-quarter required critical care beds. Clinical presentation was variable. Death was associated with host characteristics and disease-associated conditions, and vaccine was protective. Virus type did not influence outcome.

National burden of influenza-associated hospitalizations in Cambodia, 2015 and 2016.

IntroductionThe burden of influenza in Cambodia is not well known, but it would be useful for understanding the impact of seasonal epidemics and pandemics and to design appropriate policies for influenza prevention and control. The severe acute respiratory infection (SARI) surveillance system in Cambodia was used to estimate the national burden of SARI hospitalizations in Cambodia.MethodsWe estimated age-specific influenza-associated SARI hospitalization rates in three sentinel sites in Svay Rieng, Siem Reap and Kampong Cham provinces. We used influenza-associated SARI surveillance data for one year to estimate the numerator and hospital admission surveys to estimate the population denominator for each site. A national influenza-associated SARI hospitalization rate was calculated using the pooled influenza-associated SARI hospitalizations for all sites as a numerator and the pooled catchment population of all sites as denominator. National influenza-associated SARI case counts were estimated by applying hospitalization rates to the national population.ResultsThe national annual rates of influenza-associated hospitalizations per 100 000 population was highest for the two youngest age groups at 323 for < 1 year and 196 for 1–4 years. We estimated 7547 influenza-associated hospitalizations for Cambodia with almost half of these represented by children younger than 5 years.DiscussionWe present national estimates of influenza-associated SARI hospitalization rates for Cambodia based on sentinel surveillance data from three sites. The results of this study indicate that the highest burden of severe influenza infection is borne by the younger age groups. These findings can be used to guide future strategies to reduce influenza morbidity.

Hospitalizations for Influenza-Associated Severe Acute Respiratory Infection, Beijing, China, 2014–2016

We analyzed surveillance data for 2 sentinel hospitals to estimate the influenza-associated severe acute respiratory infection hospitalization rate in Beijing, China. The rate was 39 and 37 per 100,000 persons during the 2014–15 and 2015–16 influenza seasons, respectively. Rates were highest for children <5 years of age.

An outbreak investigation of paediatric severe acute respiratory infections requiring admission to intensive care units - Fiji, May 2016.

IntroductionInfluenza-associated severe acute respiratory infections (SARI) are a major contributor to global morbidity and mortality. In response to a cluster of SARI cases and deaths in pregnant women, with two deceased cases testing positive for influenza A(H1N1)pdm09, an investigation was initiated to determine whether there was an increase of paediatric SARI cases admitted to divisional hospital intensive care units in Fiji in may 2016 compared to May 2013–2015.MethodsRetrospective case finding was conducted at the paediatric intensive care units (PICUs) in Fiji’s three divisional hospitals. Data were collected from 1 January 2013 to 26 May 2016. Cases were identified using a list of clinical diagnoses compatible with SARI.ResultsA total of 632 cases of paediatric SARI with complete details were identified. The median age of cases was 6 months (Interquartile range: 2–14 months). Children aged less than 5 years had a higher rate of paediatric SARI requiring admission to a divisional hospital PICU in May 2016 compared to May 2013–2015 (Incidence rate ratio: 1.7 [95% CI: 1.1–2.6]). This increase was not observed in children aged 5–14 years. The case-fatality ratio was not significantly different in 2016 compared to previous years.ConclusionThe investigation enabled targeted public health response measures, including enhanced SARI surveillance at divisional hospitals and an emergency influenza vaccination campaign in the Northern Division.

Clinical and epidemiological characterization of influenza virus infections in children with severe acute respiratory infection in Maputo, Mozambique: Results from the implementation of sentinel surveillance, 2014 - 2016.

In Sub-Saharan Africa, where burden, impact, and incidence of acute respiratory infections (ARI) are the highest in the world, conversely, the epidemiology of influenza-associated severe acute respiratory infections (SARI) is incompletely known. The aim of this study was to describe the clinical and epidemiological features of influenza-associated SARI in hospitalized children in Maputo city, Mozambique. Nasopharyngeal and oropharyngeal swabs were collected from children aged 0–14 years old who met the case definition for SARI in two hospitals in Maputo city after their parents or legal representative consented to participate. A structured questionnaire was used to collect clinical and demographic data. Typing and subtyping of influenza were performed by real-time PCR. From January 2014 to December 2016, a total of 2,007 eligible children were recruited, of whom 1,997 (99.5%) were screened for influenza by real-time PCR. The median age of participants was 16.9 months (IQR: 7.0–38.9 months) and 53.9% (1076/1991) were male. A total of 77 were positive for influenza, yielding a frequency of 3.9% (77/1,991), with the highest frequency being reported in the age group 1–5 years old. Cases of influenza peaked twice each year, during which, its frequency reached up to 60%-80%. Among all influenza confirmed cases, 33.7% (26/77), 35.1% (27/77) and 28.6% (22/77) were typed as influenza A/H3N2, A/H1N1pdm09, and B, respectively. This represents the first report of influenza in urban/sub urban setting in Mozambique and the first evidence of distribution of strains of influenza in the country. Our data showed that frequency of influenza was lower than reported in a rural setting in Mozambique and the frequency of seasonal (A/H1N1pdm09) and (A/H3N2) subtypes were similar in children with SARI.

Using a hospital admission survey to estimate the burden of influenza-associated severe acute respiratory infection in one province of Cambodia-methods used and lessons learned.

BackgroundUnderstanding the burden of influenza‐associated severe acute respiratory infection (SARI) is important for setting national influenza surveillance and vaccine priorities. Estimating influenza‐associated SARI rates requires hospital‐based surveillance data and a population‐based denominator, which can be challenging to determine.ObjectivesWe present an application of the World Health Organization's recently developed manual (WHO Manual) including hospital admission survey (HAS) methods for estimating the burden of influenza‐associated SARI, with lessons learned to help others calculate similar estimates.MethodsUsing an existing SARI surveillance platform in Cambodia, we counted influenza‐associated SARI cases during 2015 at one sentinel surveillance site in Svay Rieng Province. We applied WHO Manual‐derived methods to count respiratory hospitalizations at all hospitals within the catchment area, where 95% of the sentinel site case‐patients resided. We used HAS methods to adjust the district‐level population denominator for the sentinel site and calculated the incidence rate of influenza‐associated SARI by dividing the number of influenza‐positive SARI infections by the adjusted population denominator and multiplying by 100 000. We extrapolated the rate to the provincial population to derive a case count for 2015. We evaluated data sources, detailed steps of implementation, and identified lessons learned.ResultsWe estimated an adjusted influenza‐associated 2015 SARI rate of 13.5/100 000 persons for the catchment area of Svay Rieng Hospital and 77 influenza‐associated SARI cases in Svay Rieng Province after extrapolation.ConclusionsMethods detailed in the WHO Manual and operationalized successfully in Cambodia can be used in other settings to estimate rates of influenza‐associated SARI.