Annual estimates of the influenza disease burden provide information to evaluate programs and allocate resources. We used a multiplier method with routine population-based surveillance data on ...influenza hospitalization in the United States to correct for under-reporting and estimate the burden of influenza for seasons after the 2009 pandemic. Five sites of the Influenza Hospitalization Surveillance Network (FluSurv-NET) collected data on the frequency and sensitivity of influenza testing during two seasons to estimate under-detection. Population-based rates of influenza-associated hospitalization and Intensive Care Unit admission from 2010-2013 were extrapolated to the U.S. population from FluSurv-NET and corrected for under-detection. Influenza deaths were calculated using a ratio of deaths to hospitalizations. We estimated that influenza-related hospitalizations were under-detected during 2010-11 by a factor of 2.1 (95%CI 1.7-2.9) for age < 18 years, 3.1 (2.4-4.5) for ages 18-64 years, and 5.2 (95%CI 3.8-8.3) for age 65+. Results were similar in 2011-12. Extrapolated estimates for 3 seasons from 2010-2013 included: 114,192-624,435 hospitalizations, 18,491-95,390 ICU admissions, and 4,915-27,174 deaths per year; 54-70% of hospitalizations and 71-85% of deaths occurred among adults aged 65+. Influenza causes a substantial disease burden in the U.S. that varies by age and season. Periodic estimation of multipliers across multiple sites and age groups improves our understanding of influenza detection in sentinel surveillance systems. Adjusting surveillance data using a multiplier method is a relatively simple means to estimate the impact of influenza and the subsequent value of interventions to prevent influenza.
Uncertain effects of the pandemic on respiratory viruses Gomez, Gabriela B.; Mahé, Cedric; Chaves, Sandra S.
Science (American Association for the Advancement of Science),
06/2021, Letnik:
372, Številka:
6546
Journal Article
Recenzirano
Expanded genomic and clinical surveillance are needed to understand the spread of respiratory viruses
The emergence and spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and ...subsequent mitigation measures have caused widespread social disruption. These disruptions have also affected community transmission of endemic diseases and the seasonal circulation patterns of other respiratory viruses. In both the Northern and Southern hemispheres, within-season influenza activity has been at historically low levels since 2020 (
1
,
2
). Additionally, the circulation of human metapneumovirus, enterovirus, adenovirus, respiratory syncytial virus (RSV), and rhinovirus has been substantially reduced (
3
). These reductions in respiratory virus infections are linked to changes in health care–seeking behaviors and limited surveillance capacity, but mostly to the widespread implementation of nonpharmacological interventions (NPIs) to control SARS-CoV-2 transmission. How this will affect the transmission patterns of endemic respiratory viruses remains unknown.
Abstract
Background
Death certificate data can improve our understanding of the mortality burden associated with respiratory syncytial virus (RSV) and influenza.
Methods
We used International ...Classification of Diseases, Tenth Revision codes listed on death certificates to characterize deaths from 1999 to 2018 as RSV, influenza, and unspecified bronchiolitis. We described the distribution of each cause of death by age, sex, race/ethnicity, place of death, and contributing causes of death.
Results
Over the 20-year study period, RSV, bronchiolitis, and influenza were listed as the underlying causes of death on 932, 1046, and 52 293 death certificates, respectively. Children <1 year of age accounted for 39% of RSV and bronchiolitis deaths, while 72% of influenza deaths were in adults ≥65 years. Children <1 year were more likely to die outside of the hospital from RSV, bronchiolitis, or influenza compared to all causes (P < .01), and black infants had the highest mortality rate for all 3 causes. Most infants dying from RSV did not have a high-risk condition listed on the death certificate. Death certificates captured 20%–60% of estimated excess RSV-attributable mortality in infants and <1% in seniors.
Conclusions
Thorough reporting on death certificates is an important public health goal, especially as new therapeutics become available. Infants had higher odds of dying out of hospital from respiratory pathogens compared to other causes, and race/ethnicity alone did not explain this disparity.
Evidence suggests that older people aged ≥65 years and those aged 60–64 years with chronic medical conditions are at higher risk of developing severe complications due to influenza virus infection ...when compared with young, healthy adults. Although seasonal influenza is monitored through a nationwide passive surveillance in Japan, influenza related outcomes and medical resource consumption have not been fully documented. This retrospective database study aimed to describe the epidemiological and clinical characteristics of medically attended influenza cases aged ≥60 years and the associated medical resource consumption in Japan. We used clinically diagnosed influenza (CDI) based on the international classification of disease codes, and laboratory-confirmed influenza (LCI) based on influenza test results, to identify the patient population during a total of nine seasons (2010/2011 to 2018/2019). A total of 372,356 CDI and 31,122 LCI cases were identified from 77 medical institutions. The highest numbers of medically-attended influenza episodes were in patients aged 65–74 years and 75–84 years. On average, across seasons, 5.9% of all-cause hospitalizations were attributable to CDI and 0.4% were LCI. Influenza viruses type A and B co-circulated annually in varying degree of intensity and were associated with similar level of complications, including cardiovascular-related. Oxygen therapy increased with age; by contrast, mechanical ventilation, dialysis, blood transfusion, and intensive care unit admission were higher in the younger groups. In-hospital mortality for inpatients aged ≥ 85 years with CDI and LCI were 18.6% and 15.5%, respectively. Considering the burden associated with medically-attended influenza in this population, influenza prevention, laboratory confirmation and clinical management should be emphasized by general practicians and specialists like cardiologists to protect this aging population.
Respiratory syncytial virus (RSV) mortality estimates have not been updated since 2009, and no study has assessed changes in influenza mortality after the 2009 pandemic. Updated burden estimates are ...needed to characterize long-term changes in the epidemiology of these viruses.
To evaluate excess mortality from RSV and influenza in the US from 1999 to 2018.
This cross-sectional study used data from 50.3 million US death certificates from 1999 to 2018 to create age-specific linear regression models and assess weekly mortality fluctuations above a seasonal baseline associated with RSV and influenza. Statistical analysis was performed for 1043 weeks from January 3, 1999, to December 29, 2018.
Excess mortality associated with RSV and influenza estimated from the difference between observed and expected underlying respiratory mortality each season.
There were 50.3 million death certificates (50.1% women and 49.9% men; mean SD age at death, 72.7 18.6 years) included in this analysis, 1.0% for children younger than 1 year and 73.4% for adults aged 65 years or older. A mean of 6549 (95% CI, 6140-6958) underlying respiratory deaths were associated with RSV annually, including 96 (95% CI, 92-99) deaths among children younger than 1 year. For influenza, there were 10 171 (95% CI, 9652-10 691) underlying respiratory deaths per year, with 23 deaths (95% CI, 19-27) among children younger than 1 year. The highest mean mortality rate per 100 000 population for both viruses was among adults aged 65 years or older at 14.7 (95% CI, 13.8-15.5) for RSV and 20.5 (95% CI, 19.4-21.5) for influenza. A lower proportion of influenza deaths occurred among those aged 65 years or older compared with earlier estimates (75.1% 95% CI, 67.4%-82.8%). Influenza mortality was highest among those aged 65 years or older in seasons when A/H3N2 predominated (18 739 95% CI, 16 616-21 336 deaths in 2017-2018) and among those aged 5 to 49 years when A/H1N1pdm2009 predominated (1683 95% CI, 1583-1787 deaths in 2013-2014). Results were sensitive to the choice of mortality outcome and method, with the broadest outcome associated with annual means of 23 352 (95% CI, 21 814-24 891) excess deaths for RSV and 27 171 (95% CI, 25 142-29 199) for influenza.
This study suggests that RSV poses a greater risk than influenza to infants, while both are associated with substantial mortality among elderly individuals. Influenza has large interannual variability, affecting different age groups depending on the circulating virus. The emergence of the influenza A/H1N1pdm2009 pandemic virus in 2009 shifted mortality toward middle-aged adults, a trend still observed to date. This study's estimates provide a benchmark to evaluate the mortality benefits associated with interventions against respiratory viruses, including new or improved immunization strategies.
Although influenza is primarily considered a respiratory infection and causes significant respiratory mortality, evidence suggests that influenza has an additional burden due to broader consequences ...of the illness. Some of these broader consequences include cardiovascular events, exacerbations of chronic underlying conditions, increased susceptibility to secondary bacterial infections, functional decline, and poor pregnancy outcomes, all of which may lead to an increased risk for hospitalization and death. Although it is methodologically difficult to measure these impacts, epidemiological and interventional study designs have evolved over recent decades to better take them into account. Recognizing these broader consequences of influenza virus infection is essential to determine the full burden of influenza among different subpopulations and the value of preventive approaches. In this review, we outline the main influenza complications and societal impacts beyond the classical respiratory symptoms of the disease.
In 2003, surveillance for influenza in hospitalized persons was added to the Centers for Disease Control and Prevention Emerging Infections Program network. This surveillance enabled monitoring of ...the severity of influenza seasons and provided a platform for addressing priority questions associated with influenza. For enhanced surveillance capacity during the 2009 influenza pandemic, new sites were added to this platform. The combined surveillance platform is called the Influenza Hospitalization Surveillance Network (FluSurv-NET). FluSurv-NET has helped to determine the risk for influenza-associated illness in various segments of the US population, define the severity of influenza seasons and the 2009 pandemic, and guide recommendations for treatment and vaccination programs.
Background. We investigated the effect of influenza vaccination on disease severity in adults hospitalized with laboratory-confirmed influenza during 2013–14, a season in which vaccine viruses were ...antigenically similar to those circulating. Methods. We analyzed data from the 2013–14 influenza season and used propensity score matching to account for the probability of vaccination within age strata (18–49, 50–64, and ≥65 years). Death, intensive care unit (ICU) admission, and hospital and ICU lengths of stay (LOS) were outcome measures for severity. Multivariable logistic regression and competing risk models were used to compare disease severity between vaccinated and unvaccinated patients, adjusting for timing of antiviral treatment and time from illness onset to hospitalization. Results. Influenza vaccination was associated with a reduction in the odds of in-hospital death among patients aged 18–49 years (adjusted odds ratios aOR = 0.21; 95% confidence interval CI, 0.05 to 0.97), 50–64 years (aOR = 0.48; 95% CI, 0.24 to 0.97), and ≥65 years (aOR = 0.39; 95% CI, 0.17 to 0.66). Vaccination also reduced ICU admission among patients aged 18–49 years (aOR = 0.63; 95% CI, 0.42 to 0.93) and ≥65 years (aOR = 0.63; 95% CI, 0.48 to 0.81), and shortened ICU LOS among those 50–64 years (adjusted relative hazards aRH = 1.36; 95% CI, 1.06 to 1.74) and ≥65 years (aRH = 1.34; 95% CI, 1.06 to 1.73), and hospital LOS among 50–64 years (aRH = 1.13; 95% CI, 1.02 to 1.26) and ≥65 years (aRH = 1.24; 95% CI, 1.13 to 1.37). Conclusions. Influenza vaccination during 2013–14 influenza season attenuated adverse outcome among adults that were hospitalized with laboratory-confirmed influenza.
In this randomized trial, oseltamivir, when initiated an average of 5 days post symptom onset, did not reduce clinical failure in hospitalized patients with influenza-associated lower respiratory ...tract infection (I-LRTI). Oseltamivir may not reduce failure in hospitalized patients with I-LRTI.
Abstract
Background
Influenza-associated hospitalizations result in high morbidity and mortality. We sought to determine if early empiric anti-influenza therapy improves outcomes of hospitalized patients with influenza-associated lower respiratory tract infections (I-LRTIs).
Methods
This was a randomized, unblinded, trial of adult patients hospitalized with I-LRTIs in Kentucky during 2009-2012. Patients were randomized to group A (standard of care) or group B (standard of care plus oseltamivir as early as possible but within 24 hours of enrollment). The primary outcome was development of clinical failure (composite variable including failure to reach clinical improvement within 7 days, transfer to intensive care 24 hours after admission, or rehospitalization or death within 30 days). Intent-to-treat (ITT) (all LRTI) and per-protocol (PP) (I-LRTI) analyses were done.
Results
A total of 1107 patients were enrolled and included in the ITT analysis, 556 in group A and 551 in group B. The median time from symptom onset to hospital admission was 5 days (interquartile range, 5) for both groups; oseltamivir was initiated median day 6 in group B. There was no difference in the development of clinical failure (group A, 25%, and group B, 24%; P = .561). In the PP analysis, 11 of 45 (24%) patients in group A and 4 of 29 (14%) patients in group B had clinical failure (P = .414).
Conclusions
Initiation of oseltamivir more than 5 days after illness onset did not reduce clinical failures among hospitalized patients with I- LRTIs. However, we did not enroll our projected sample size of I-LRTI.
Clinical Trials Registration
NCT01248715.
Abstract
Background
High-dose (HD) influenza vaccine offers improved protection from influenza virus infection among older adults compared with standard-dose (SD) vaccine. Here, we explored whether ...HD vaccine attenuates disease severity among older adults with breakthrough influenza.
Methods
This was a retrospective cohort study of US claims data for influenza seasons 2016–2017, 2017–2018, and 2018–2019, defined as 1 October through 30 April, among adults aged ≥65 years. After adjusting the different cohorts for the probability of vaccination conditional on patients’ characteristics, we compared 30-day mortality rate post-influenza among older adults who experienced breakthrough infection after receipt of HD or SD influenza vaccines and among those not vaccinated (NV).
Results
We evaluated 44 456 influenza cases: 23 109 (52%) were unvaccinated, 15 037 (33.8%) received HD vaccine, and 6310 (14.2%) received SD vaccine. Significant reductions in mortality rates among breakthrough cases were observed across all 3 seasons for HD vs NV, ranging from 17% to 29% reductions. A significant mortality reduction of 25% was associated with SD vaccination vs NV in the 2016–2017 season when there was a good match between circulating influenza viruses and selected vaccine strains. When comparing HD vs SD cohorts, mortality reductions were higher among those who received HD in the last 2 seasons when mismatch between vaccine strains and circulating H3N2 viruses was documented, albeit not significant.
Conclusions
HD vaccination was associated with lower post-influenza mortality among older adults with breakthrough influenza, even during seasons when antigenically drifted H3N2 circulated. Improved understanding of the impact of different vaccines on attenuating disease severity is warranted when assessing vaccine policy recommendations.
High-dose vaccination among people aged ≥65 years with breakthrough influenza was associated with lower post-influenza mortality, even during seasons when antigenically drifted H3N2 circulated. Attenuation of disease severity should be included when assessing vaccine policy recommendations.
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