Influenza-associated Respiratory Illness Research Articles

Influenza-associated respiratory illness among five cohorts of pregnant women and their young infants (0-6months), Bangladesh, 2013-2017.

Pregnant women with their infants are considered at higher risk for influenza-associated complications, and the World Health Organization (WHO) recommends influenza vaccination during pregnancy to protect them, including their infants (0-6months). There are limited data on the influenza burden among pregnant women and their infants (0-6months), and there are no routine influenza vaccinations in Bangladesh. Five annual cohorts (2013-2017) of pregnant women were enrolled from the eight sub-districts of Bangladesh before the influenza season (May-September); they were contacted weekly to identify new onset of influenza-like illness (ILI) (subjective or measured fever and cough) and acute respiratory illness (ARI) (at least two of these symptoms: cough, rhinorrhea, or difficulty in breathing) among their infants from birth to 6 months of age. We collected nasopharyngeal swabs from ILI and ARI cases, tested by real-time reverse transcription polymerase chain reaction (rRT-PCR) for influenza virus (including types and subtypes) and estimated influenza incidence (95% CI)/10000 pregnant women-months or infant-months, respectively. We enrolled 9020 pregnant women, followed for 26,709 pregnancy-months, and detected 1241 ILI episodes. We also followed 8963 infants for 51,518 infant-months and identified 5116 ARI episodes. Influenza positivity was 23% for ILI and 3% for ARI cases. The overall incidence (2013-2017) of influenza among pregnant women was 158.5/10000 pregnant women-months (95% CI: 141.4-177.6) and that among infants was 21.9/10000 infant-months (95% CI: 18.2-26.5). Although the data was collected more than 5 years ago, as the only baseline data, our findings illustrate evidence of influenza burden among pregnant women and infants (0-6months), which may support preventive policy decisions in Bangladesh.

Dynamics of Anti-influenza Mucosal IgA Over a Season in a Cohort of Individuals Living or Working in a Long-term Care Facility.

Serological surveys are used to ascertain influenza infection and immunity, but evidence for the utility of mucosal immunoglobulin A (IgA) as a correlate of infection or protection is limited. We performed influenza-like illness (ILI) surveillance on 220 individuals living or working in a retirement community in Gainesville, Florida from January to May 2018, and took pre- and postseason nasal samples of 11 individuals with polymerase chain reaction (PCR)-confirmed influenza infection and 60 randomly selected controls. Mucosal IgA against 10 strains of influenza was measured from nasal samples. Overall, 28.2% and 11.3% of individuals experienced a 2-fold and 4-fold rise, respectively, in mucosal IgA to at least 1 influenza strain. Individuals with PCR-confirmed influenza A had significantly lower levels of preseason IgA to influenza A. Influenza-associated respiratory illness was associated with a higher rise in mucosal IgA to influenza strains of the same subtype, and H3N2-associated respiratory illness was associated with a higher rise in mucosal IgA to other influenza A strains. By comparing individuals with and without influenza illness, we demonstrated that mucosal IgA is a correlate of influenza infection. There was evidence for cross-reactivity in mucosal IgA across influenza A subtypes.

Risk Factors of Influenza-Associated Respiratory Illnesses Reported to a Sentinel Hospital of Lahore, Pakistan: 2015-2016.

Epidemiological data about determinants of influenza A virus (IAV) in the Pakistani population is scarce. We aimed to conduct a prospective hospital-based active surveillance study from October 2015 to May 2016 to identify potential risk factors associated with IAV infection among patients with influenza-like illness (ILI) and severe acute respiratory illness (SARI). Surveillance was conducted in Lahore General Hospital, selected as a sentinel site in Lahore District, Pakistan. Nasal/throat samples were collected along with epidemiological and clinical data from enrolled patients. Real-time reverse-transcription polymerase chain reaction (rRT-PCR) was performed to identify IAV and its subtypes (H1N1pdm09, H3N2). Data were analyzed to determine risk factors and risk markers associated with IAV infections. A total of 311 suspected ILI and SARI cases were enrolled in the study, and among these 50 were IAV-positive. Of these 50 confirmed cases of IAV, 14 were subtyped as H1N1pdm09 and 15 were H3N2; the remaining 21 were untyped. A final multivariable model identified four independent risk factors/markers for IAV infection: exposure history to ILI patients within last 7 days and gender being male were identified as risk factors of IAV infection, while use of antibiotics prior to hospital consultation and presence of fever were identified as risk markers. We concluded that adopting nonpharmaceutical interventions like hand hygiene, masks, social distancing, and where possible, avoiding identified risk factors could decrease the risk of IAV infection and may prevent imminent outbreaks of IAV in the community.

Health and economic burden of influenza-associated illness in South Africa, 2013-2015.

BackgroundEconomic burden estimates are essential to guide policy‐making for influenza vaccination, especially in resource‐limited settings.MethodsWe estimated the cost, absenteeism, and years of life lost (YLL) of medically and non‐medically attended influenza‐associated mild and severe respiratory, circulatory and non‐respiratory/non‐circulatory illness in South Africa during 2013‐2015 using a modified version of the World Health Organization (WHO) worksheet based tool for estimating the economic burden of seasonal influenza. Additionally, we restricted the analysis to influenza‐associated severe acute respiratory illness (SARI) and influenza‐like illness (ILI; subsets of all‐respiratory illnesses) as suggested in the WHO manual.ResultsThe estimated mean annual cost of influenza‐associated illness was $270.5 million, of which $111.3 million (41%) were government‐incurred costs, 40.7 million (15%) were out‐of‐pocket expenses, and $118.4 million (44%) were indirect costs. The cost of influenza‐associated medically attended mild illness ($107.9 million) was 2.3 times higher than that of severe illness ($47.1 million). Influenza‐associated respiratory illness costs ($251.4 million) accounted for 93% of the total cost. Estimated absenteeism and YLL were 13.2 million days and 304 867 years, respectively. Among patients with influenza‐associated WHO‐defined ILI or SARI, the costs ($95.3 million), absenteeism (4.5 million days), and YLL (65 697) were 35%, 34%, and 21% of the total economic and health burden of influenza.ConclusionThe economic burden of influenza‐associated illness was substantial from both a government and a societal perspective. Models that limit estimates to those obtained from patients with WHO‐defined ILI or SARI substantially underestimated the total economic and health burden of influenza‐associated illness.

Quantifying How Different Clinical Presentations, Levels of Severity, and Healthcare Attendance Shape the Burden of Influenza-associated Illness: A Modeling Study From South Africa.

Burden estimates of medically and nonmedically attended influenza-associated illness across syndromes and levels of severity are lacking. We estimated the national burden of medically and nonmedically attended influenza-associated illness among individuals with different clinical presentations (all-respiratory, all-circulatory, and nonrespiratory/noncirculatory) and levels of severity (mild, fatal, and severe, nonfatal) using a combination of case-based (from laboratory-confirmed influenza surveillance) and ecological studies, as well as data from healthcare utilization surveys in South Africa during 2013-2015. In addition, we compared estimates of medically attended influenza-associated respiratory illness, obtained from case-based and ecological studies. Rates were reported per 100 000 individuals in the population. The estimated mean annual number of influenza-associated illness episodes was 10 737 847 (19.8% of 54 096 705 inhabitants). Of these episodes, 10 598 138 (98.7%) were mild, 128 173 (1.2%) were severe, nonfatal, and 11 536 (0.1%) were fatal. There were 2 718 140 (25.6%) mild, 56 226 (43.9%) severe, nonfatal, and 4945 (42.8%) medically attended should be after fatal episodes. Influenza-associated respiratory illness accounted for 99.2% (10 576 146) of any mild, 65.5% (83 941) of any severe, nonfatal, and 33.7% (3893) of any fatal illnesses. Ecological and case-based estimates of medically attended, influenza-associated, respiratory mild (rates: ecological, 1778.8, vs case-based, 1703.3; difference, 4.4%), severe, nonfatal (rates: ecological, 88.6, vs case-based, 75.3; difference, 15.0%), and fatal (rates: ecological, 3.8, vs case-based, 3.5; difference, 8.4%) illnesses were similar. There was a substantial burden of influenza-associated symptomatic illness, including severe, nonfatal and fatal illnesses, and a large proportion was nonmedically attended. Estimates, including only influenza-associated respiratory illness, substantially underestimated influenza-associated, severe, nonfatal and fatal illnesses. Ecological and case-based estimates were found to be similar for the compared categories.

Cohort profile: China respiratory illness surveillance among pregnant women (CRISP), 2015–2018

PurposeWe established the China Respiratory Illness Surveillance among Pregnant women (CRISP) to conduct active surveillance for influenza-associated respiratory illness during pregnancy in China from 2015 to 2018. Among annual cohorts...

The effects of the attributable fraction and the duration of symptoms on burden estimates of influenza-associated respiratory illnesses in a high HIV prevalence setting, South Africa, 2013-2015.

BackgroundThe attributable fraction of influenza virus detection to illness (INF‐AF) and the duration of symptoms as a surveillance inclusion criterion could potentially have substantial effects on influenza disease burden estimates.MethodsWe estimated rates of influenza‐associated influenza‐like illness (ILI) and severe acute (SARI‐10) or chronic (SCRI‐10) respiratory illness (using a symptom duration cutoff of ≤10 days) among HIV‐infected and HIV‐uninfected patients attending 3 hospitals and 2 affiliated clinics in South Africa during 2013‐2015. We calculated the unadjusted and INF‐AF‐adjusted rates and relative risk (RR) due to HIV infection. Rates were expressed per 100 000 population.ResultsThe estimated mean annual unadjusted rates of influenza‐associated illness were 1467.7, 50.3, and 27.4 among patients with ILI, SARI‐10, and SCRI‐10, respectively. After adjusting for the INF‐AF, the percent reduction in the estimated rates was 8.9% (rate: 1336.9), 11.0% (rate: 44.8), and 16.3% (rate: 22.9) among patients with ILI, SARI‐10, and SCRI‐10, respectively. HIV‐infected compared to HIV‐uninfected individuals experienced a 2.3 (95% CI: 2.2‐2.4)‐, 9.7 (95% CI: 8.0‐11.8)‐, and 10.0 (95% CI: 7.9‐12.7)‐fold increased risk of influenza‐associated illness among patients with ILI, SARI‐10, and SCRI‐10, respectively. Overall 34% of the estimated influenza‐associated hospitalizations had symptom duration of >10 days; 8% and 44% among individuals aged <5 and ≥5 years, respectively.ConclusionThe marginal differences between unadjusted and INF‐AF‐adjusted rates are unlikely to affect policies on prioritization of interventions. HIV‐infected individuals experienced an increased risk of influenza‐associated illness and may benefit more from annual influenza immunization. The use of a symptom duration cutoff of ≤10 days may underestimate influenza‐associated disease burden, especially in older individuals.

Quantifying How Different Clinical Presentations, Levels of Severity and Healthcare Attendance Shape the Burden of Influenza-Associated Illness: A Modeling Study from South Africa

Background Burden estimates of medically and nonmedically attended influenza-associated illness across syndromes and levels of severity are lacking. Methods We estimated the national burden of medically and nonmedically attended influenza-associated illness among individuals with different clinical presentations (all-respiratory, all-circulatory, and nonrespiratory/noncirculatory) and levels of severity (mild, fatal, and severe, nonfatal) using a combination of case-based (from laboratory-confirmed influenza surveillance) and ecological studies, as well as data from healthcare utilization surveys in South Africa during 2013-2015. In addition, we compared estimates of medically attended influenza-associated respiratory illness, obtained from case-based and ecological studies. Rates were reported per 100 000 individuals in the population. Results The estimated mean annual number of influenza-associated illness episodes was 10 737 847 (19.8% of 54 096 705 inhabitants). Of these episodes, 10 598 138 (98.7%) were mild, 128 173 (1.2%) were severe, nonfatal, and 11 536 (0.1%) were fatal. There were 2 718 140 (25.6%) mild, 56 226 (43.9%) severe, nonfatal, and 4945 (42.8%) medically attended should be after fatal episodes. Influenza-associated respiratory illness accounted for 99.2% (10 576 146) of any mild, 65.5% (83 941) of any severe, nonfatal, and 33.7% (3893) of any fatal illnesses. Ecological and case-based estimates of medically attended, influenza-associated, respiratory mild (rates: ecological, 1778.8, vs case-based, 1703.3; difference, 4.4%), severe, nonfatal (rates: ecological, 88.6, vs case-based, 75.3; difference, 15.0%), and fatal (rates: ecological, 3.8, vs case-based, 3.5; difference, 8.4%) illnesses were similar. Conclusions There was a substantial burden of influenza-associated symptomatic illness, including severe, nonfatal and fatal illnesses, and a large proportion was nonmedically attended. Estimates, including only influenza-associated respiratory illness, substantially underestimated influenza-associated, severe, nonfatal and fatal illnesses. Ecological and case-based estimates were found to be similar for the compared categories.

Uptake and Effectiveness of a Trivalent Inactivated Influenza Vaccine in Children in Urban and Rural Kenya, 2010 to 2012.

In Africa, recent surveillance has demonstrated a high burden of influenza, but influenza vaccine is rarely used. In Kenya, a country with a tropical climate, influenza has been shown to circulate year-round, like in other tropical countries. During 3 months in 2010 and 2011 and 2 months in 2012, the Kenya Medical Research Institute/Centers for Disease Control and Prevention-Kenya offered free injectable trivalent inactivated influenza vaccine to children 6 months to 10 years old in 2 resource-poor communities in Kenya-Kibera and Lwak (total population ~50,000). We conducted a case-control study to evaluate vaccine effectiveness (VE) in preventing laboratory-confirmed influenza associated with influenza-like illness and acute lower respiratory illness. Of the approximately 18,000 eligible children, 41%, 48% and 51% received at least 1 vaccine in 2010, 2011 and 2012, respectively; 30%, 36% and 38% were fully vaccinated. VE among fully vaccinated children was 57% [95% confidence interval (CI): 29% to 74%] during a 6-month follow-up period, 39% (95% CI: 17% to 56%) during a 9-month follow-up period and 48% (95% CI: 32% to 61%) during a 12-month follow-up period. For the 12-month follow-up period, VE was statistically significant in children <5 years and in children 5 to <10 years old (50% and 46%, respectively). In Kenya, parents of nearly half of the eligible children <10 years old chose to get their children vaccinated with a free influenza vaccine. During a 12-month follow-up period, the vaccine was moderately effective in preventing medically attended influenza-associated respiratory illness.

Oseltamivir and the risk of influenza-related complications and hospitalizations in patients with diabetes

Objective: This subgroup analysis of a retrospective cohort study examined, from a managed care perspective, the risk of influenza-related complications and hospitalizations in patients with diabetes who were prescribed oseltamivir for the treatment of influenza and those who were not prescribed antiviral treatment. Methods: Health insurance claims data from the Thomson Healthcare MarketScan Research Database for 6 influenza seasons (October 1-March 31) between 2000 and 2006 were used to identify patients aged ≥18 years with influenza and diabetes. Patients who received a prescription for oseltamivir within 1 day of a diagnosis of influenza were compared with those who received no antiviral treatment. Outcomes included the frequency of pneumonia, respiratory diagnoses, and otitis media and its complications, and rates of hospitalization within 14 days of the diagnosis of influenza. Cox proportional hazards regression was used to determine the relative risk (RR) of influenza-related complications and hospitalizations. Results: A total of 9090 patients with diabetes and a diagnosis of influenza were identified who met all study criteria. Of these, 2919 (32%) received a prescription for oseltamivir and 6171 (68%) received no antiviral treatment. Patients receiving oseltamivir had a significant 17% reduction in the risk of respiratory illnesses (RR = 0.83; 95% CI, 0.73-0.93) and a 30% reduction in the risk of hospitalization for any reason (RR = 0.70; 95% CI, 0.52-0.94). There were no significant differences between the oseltamivir and control groups in terms of the risks for pneumonia (RR = 0.87; 95% CI, 0.64-1.18), otitis media and its complications (RR = 0.96; 95% CI, 0.48-1.91), or hospitalization for pneumonia (RR = 0.81; 95% CI, 0.41-1.58). Conclusion: In this retrospective study, the risk of influenza-associated respiratory illnesses and the number of hospitalizations for any reason were reduced in patients with diabetes who were prescribed oseltamivir compared with an unmatched group that was not prescribed antiviral therapy.

1340 PUBLICATION Analysis of haematological risk factors for thromboembolic events in anaemic cancer patients treated with epoetin beta

Objective: This subgroup analysis of a retrospective cohort study examined, from a managed care perspective, the risk of influenza-related complications and hospitalizations in patients with diabetes who were prescribed oseltamivir for the treatment of influenza and those who were not prescribed antiviral treatment.Methods: Health insurance claims data from the Thomson Healthcare MarketScan Research Database for 6 influenza seasons (October 1-March 31) between 2000 and 2006 were used to identify patients aged ≥18 years with influenza and diabetes. Patients who received a prescription for oseltamivir within 1 day of a diagnosis of influenza were compared with those who received no antiviral treatment. Outcomes included the frequency of pneumonia, respiratory diagnoses, and otitis media and its complications, and rates of hospitalization within 14 days of the diagnosis of influenza. Cox proportional hazards regression was used to determine the relative risk (RR) of influenza-related complications and hospitalizations.Results: A total of 9090 patients with diabetes and a diagnosis of influenza were identified who met all study criteria. Of these, 2919 (32%) received a prescription for oseltamivir and 6171 (68%) received no antiviral treatment. Patients receiving oseltamivir had a significant 17% reduction in the risk of respiratory illnesses (RR = 0.83; 95% CI, 0.73-0.93) and a 30% reduction in the risk of hospitalization for any reason (RR = 0.70; 95% CI, 0.52-0.94). There were no significant differences between the oseltamivir and control groups in terms of the risks for pneumonia (RR = 0.87; 95% CI, 0.64-1.18), otitis media and its complications (RR = 0.96; 95% CI, 0.48-1.91), or hospitalization for pneumonia (RR = 0.81; 95% CI, 0.41-1.58).Conclusion: In this retrospective study, the risk of influenza-associated respiratory illnesses and the number of hospitalizations for any reason were reduced in patients with diabetes who were prescribed oseltamivir compared with an unmatched group that was not prescribed antiviral therapy.

Exploring Reasons for Bed Pressures in Winnipeg Acute Care Hospitals

Hospital overcrowding has plagued Winnipeg and other Canadian cities for years. This study explored factors related to overcrowding. Hospital files were used to examine patterns of hospital use from fiscal years 1996/1997 to 1999/2000. Chart reviews were conducted to examine appropriateness of admissions and hospital stays during one pressure week. Results indicate that pressure periods in the hospital system were driven by an influx of older adults with influenza-associated respiratory illnesses. Moreover, examination of one specific pressure week showed that at least 100 beds were occupied by patients who likely did not require acute care. The chart review revealed that a substantial proportion of non-acute patient-days were spent awaiting home care, long-term care, or diagnostic testing services. These findings suggest future bed pressures might be prevented through influenza vaccination and an increase in the availability of--and timely transfer to--alternative levels of care.

The Impact of Influenza-associated Respiratory Illnesses on Hospitalizations, Physician Visits, Emergency Room Visits, and Mortality

Although the increased risk of hospitalization and mortality during influenza seasons has been documented extensively, there is a relative paucity of research on the impact of influenza-related illnesses on other health care use indicators, such as physician use. The purpose of this study was to examine the impact of influenza-associated respiratory illnesses on the Winnipeg health care system, including hospitalizations, physician visits and emergency room visits. Their impact on mortality was also examined.Administrative data were used to track health care use and mortality over four influenza seasons (1995-96 to 1998-99). Excess health care use and deaths were calculated by subtracting rates during influenza seasons from those during weeks when influenza viruses were not circulating.Significant excess hospitalization, physician visit, and emergency room visit rates emerged for influenza and pneumonia, acute respiratory diseases, and chronic lung disease, especially among children and adults aged 65 and over. Considerable excess mortality due to influenza and pneumonia and chronic lung disease among individuals aged 65 and over also emerged, particularly among nursing home residents.Influenza-associated respiratory illnesses have a substantial impact on the health care system. Given the burden of illness among children during influenza seasons, the study further suggests that influenza vaccination might be considered for this age group.

Health impact of influenza in the United States.

Influenza infection is associated with significant morbidity and mortality. The purpose of this investigation was to describe the health effects of influenza in the US. Although a number of different data sources have been used to provide estimates of the health impact of influenza in the US, estimates provided in this article are primarily based upon the experiences reported in community-based studies performed in Houston, Texas, and Tecumseh, Michigan. Estimates of the annual average are provided for the following: (1) infection rate; (2) number of influenza-associated respiratory illnesses; (3) number of ill days with influenza; (4) number of bed and activity restriction days due to influenza illness; (5) physician visits; (6) hospitalisations and days hospitalised; and (7) mortality. Large differences were found between estimates from Houston and Tecumseh, and possible explanations for these are provided. However, all estimates find that influenza is an important cause of morbidity and mortality in the US.