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The formulation of accurate clinical case definitions is an integral part of an effective process of public health surveillance. Although such definitions should, ideally, be based on a standardized and fixed collection of defining criteria, they often require revision to reflect new knowledge of the condition involved and improvements in diagnostic testing. Optimal case definitions also need to have a balance of sensitivity and specificity that reflects their intended use. After the 2009-2010 H1N1 influenza pandemic, the World Health Organization (WHO) initiated a technical consultation on global influenza surveillance. This prompted improvements in the sensitivity and specificity of the case definition for influenza - i.e. a respiratory disease that lacks uniquely defining symptomology. The revision process not only modified the definition of influenza-like illness, to include a simplified list of the criteria shown to be most predictive of influenza infection, but also clarified the language used for the definition, to enhance interpretability. To capture severe cases of influenza that required hospitalization, a new case definition was also developed for severe acute respiratory infection in all age groups. The new definitions have been found to capture more cases without compromising specificity. Despite the challenge still posed in the clinical separation of influenza from other respiratory infections, the global use of the new WHO case definitions should help determine global trends in the characteristics and transmission of influenza viruses and the associated disease burden.

Abstract Background Severe influenza illness is presumed more common in adults with chronic medical conditions (CMCs), but evidence is sparse and often combined into broad CMC categories. Methods Residents (aged 18–80 years) of Central and South Auckland hospitalized for World Health Organization-defined severe acute respiratory illness (SARI) (2012–2015) underwent influenza virus polymerase chain reaction testing. The CMC statuses for Auckland residents were modeled using hospitalization International Classification of Diseases, Tenth Revision codes, pharmaceutical claims, and laboratory results. Population-level influenza rates in adults with congestive heart failure (CHF), coronary artery disease (CAD), cerebrovascular accidents (CVA), chronic obstructive pulmonary disease (COPD), asthma, diabetes mellitus (DM), and end-stage renal disease (ESRD) were calculated by Poisson regression stratified by age and adjusted for ethnicity. Results Among 891 276 adults, 2435 influenza-associated SARI hospitalizations occurred. Rates were significantly higher in those with CMCs compared with those without the respective CMC, except for older adults with DM or those aged <65 years with CVA. The largest effects occurred with CHF (incidence rate ratio [IRR] range, 4.84–13.4 across age strata), ESRD (IRR range, 3.30–9.02), CAD (IRR range, 2.77–10.7), and COPD (IRR range, 5.89–8.78) and tapered with age. Conclusions Our findings support the increased risk of severe, laboratory-confirmed influenza disease among adults with specific CMCs compared with those without these conditions. Population-based surveillance of acute respiratory infections among Auckland, New Zealand residents during 2012–2015 revealed significantly higher incidence and risk of influenza-related hospitalizations in adults with chronic medical conditions, with the largest effects occurring in CHF, ESRD, CAD, and COPD.

Studies in the literature have indicated that the timing of seasonal influenza epidemic varies across latitude, suggesting the involvement of meteorological and environmental conditions in the transmission of influenza. In this study, we investigated the link between meteorological parameters and influenza activity in 9 sub-national areas with temperate and subtropical climates: Berlin (Germany), Ljubljana (Slovenia), Castile and León (Spain) and all 6 districts in Israel. We estimated weekly influenza-associated influenza-like-illness (ILI) or Acute Respiratory Infection (ARI) incidence to represent influenza activity using data from each country's sentinel surveillance during 2000-2011 (Spain) and 2006-2011 (all others). Meteorological data was obtained from ground stations, satellite and assimilated data. Two generalized additive models (GAM) were developed, with one using specific humidity as a covariate and another using minimum temperature. Precipitation and solar radiation were included as additional covariates in both models. The models were adjusted for previous weeks' influenza activity, and were trained separately for each study location. Influenza activity was inversely associated (p<0.05) with specific humidity in all locations. Minimum temperature was inversely associated with influenza in all 3 temperate locations, but not in all subtropical locations. Inverse associations between influenza and solar radiation were found in most locations. Associations with precipitation were location-dependent and inconclusive. We used the models to estimate influenza activity a week ahead for the 2010/2011 period which was not used in training the models. With exception of Ljubljana and Israel's Haifa District, the models could closely follow the observed data especially during the start and the end of epidemic period. In these locations, correlation coefficients between the observed and estimated ranged between 0.55 to 0.91and the model-estimated influenza peaks were within 3 weeks from the observations. Our study demonstrated the significant link between specific humidity and influenza activity across temperate and subtropical climates, and that inclusion of meteorological parameters in the surveillance system may further our understanding of influenza transmission patterns.

Background The 2009 H1N1 pandemic highlighted the need to routinely monitor severe influenza, which lead to the establishment of sentinel hospital-based surveillance of severe acute respiratory infections (SARI) in several countries in Europe. The objective of this study is to describe characteristics of SARI patients and to explore risk factors for a severe outcome in influenza-positive SARI patients. Methods Data on hospitalised patients meeting a syndromic SARI case definition between 2009 and 2012 from nine countries in Eastern Europe (Albania, Armenia, Belarus, Georgia, Kazakhstan, Kyrgyzstan, Romania, Russian Federation and Ukraine) were included in this study. An exploratory analysis was performed to assess the association between risk factors and a severe (ICU, fatal) outcome in influenza-positive SARI patients using a multivariate logistic regression analysis. Results Nine countries reported a total of 13,275 SARI patients. The majority of SARI patients reported in these countries were young children. A total of 12,673 SARI cases (95%) were tested for influenza virus and 3377 (27%) were laboratory confirmed. The majority of tested SARI cases were from Georgia, the Russian Federation and Ukraine and the least were from Kyrgyzstan. The proportion positive varied by country, season and age group, with a tendency to a higher proportion positive in the 15+ yrs age group in six of the countries. ICU admission and fatal outcome were most often recorded for influenza-positive SARI cases aged >15 yrs. An exploratory analysis using pooled data from influenza-positive SARI cases in three countries showed that age > 15 yrs, having lung, heart, kidney or liver disease, and being pregnant were independently associated with a fatal outcome. Conclusions Countries in Eastern Europe have been able to collect data through routine monitoring of severe influenza and results on risk factors for a severe outcome in influenza-positive SARI cases have identified several risk groups. This is especially relevant in the light of an overall low vaccination uptake and antiviral use in Eastern Europe, since information on risk factors will help in targeting and prioritising vulnerable populations.

The early success of the demonstration Program of All-Inclusive Care for the Elderly (PACE) led to its designation as a permanent Medicare program in 1997. But the growth in the number of programs and enrollment has lagged and does not meet expectations. This article offers insights into the mechanisms influencing the expansion of PACE, from information obtained in interviews and surveys of administrators, medical directors, and financial officers in 27 PACE programs. Sixteen barriers to expansion were found, including competition, PACE model characteristics, poor understanding of the program among referral sources, and a lack of financing for expansion. This experience offers important lessons for providing integrated health care to the frail elderly.

The Program of All-Inclusive Care for the Elderly (PACE) is a unique program providing a full spectrum of health care services, from primary to acute to long-term care for frail elderly individuals certified to require nursing home care. The objective of this article is to identify program characteristics associated with better risk-adjusted health outcomes: mortality, functional status, and self-assessed health. The article examines statistical analyses of information combining DataPACE (individual-level clinical data), a survey of direct care staff about team performance, and interviews with management in twenty-three PACE programs. Several program characteristics were associated with better functional outcomes. Fewer were associated with long-term self-assessed health, and only one with mortality. These findings offer strategies that may lead to better care.

Objective: The objective of this study was to test the hypothesis that social support is an important predictor of mortality in a frail older population receiving formal long-term care services. Research Design and Methods: The analysis is based on 3138 individuals enrolled in 28 Programs of All-Inclusive Care for the Elderly (PACE). Information about the enrollees is obtained from dataPACE. Semiparametric Cox proportional hazards models are estimated to assess the importance of individual risk factors, program effect, and social support. Results: The introduction of the social support variables into the mortality model containing the sociodemographic, health needs, and the PACE-site indicator variables results in a significant improvement of the overall model fit. Several social support variables are statistically significant predictors of mortality. Controlling for all participant and caregiver characteristics, participants whose caregiver is a spouse have a significantly lower risk of mortality (hazard ratio = 0.63) compared with those whose caregiver is not a spouse. Furthermore, caregivers' assistance with meals confers a significantly lower risk of morality (hazard ratio = 0.66) compared with no assistance with meals. Conclusions: This study shows that certain aspects of informal caregiving are important factors enhancing survival in a population of frail, nursing home-certifiable individuals enrolled in a health program that already provides extensive services, including personal care, chores, and meals. Further research to better differentiate between the affective versus the instrumental dimensions of social support is needed to guide programs on how to balance the use of resources to provide both the necessary formal services and the support for the informal caregivers.

Abstract Background Understanding the attack rate of influenza infection and the proportion who become ill by risk group is key to implementing prevention measures. While population-based studies of antihemagglutinin antibody responses have been described previously, studies examining both antihemagglutinin and antineuraminidase antibodies are lacking. Methods In 2015, we conducted a seroepidemiologic cohort study of individuals randomly selected from a population in New Zealand. We tested paired sera for hemagglutination inhibition (HAI) or neuraminidase inhibition (NAI) titers for seroconversion. We followed participants weekly and performed influenza polymerase chain reaction (PCR) for those reporting influenza-like illness (ILI). Results Influenza infection (either HAI or NAI seroconversion) was found in 321 (35% [95% confidence interval, 32%–38%]) of 911 unvaccinated participants, of whom 100 (31%) seroconverted to NAI alone. Young children and Pacific peoples experienced the highest influenza infection attack rates, but overall only a quarter of all infected reported influenza PCR–confirmed ILI, and one-quarter of these sought medical attention. Seroconversion to NAI alone was higher among children aged <5 years vs those aged ≥5 years (14% vs 4%; P < .001) and among those with influenza B vs A(H3N2) virus infections (7% vs 0.3%; P < .001). Conclusions Measurement of antineuraminidase antibodies in addition to antihemagglutinin antibodies may be important in capturing the true influenza infection rates. New Zealand’s seroepidemiological cohort study found that neuraminidase inhibition assay identified more influenza virus infections than hemagglutination inhibition assay. This result highlights the importance to measure serologically defined infections against not just hemagglutinin but also neuraminidase antigens in future seroepidemiologic cohort studies.

Background Influenza is responsible for substantial morbidity and mortality, but there is limited information on reliable disease burden estimates, especially from middle‐income countries in the WHO European Region. Objectives To estimate the incidence of medically attended influenza‐associated influenza‐like illness (ILI) and hospitalizations due to severe acute respiratory infection (SARI) presenting to public healthcare facilities in Romania. Patients/Methods Sentinel influenza surveillance data for ILI and SARI from 2011/12‐2015/16, including virological data, were used to estimate influenza‐associated ILI and SARI incidence/100 000 and their 95% confidence intervals (95% CI). Results The overall annual incidence of ILI and influenza‐associated ILI per 100 000 persons in Romania varied between 68 (95% CI: 61‐76) and 318 (95% CI: 298‐338) and between 23 (95% CI: 19‐29) and 189 (95% CI: 149‐240), respectively. The highest ILI and influenza incidence was among children aged 0‐4 years. We estimated that SARI incidence per 100 000 persons was 6 (95% CI: 5‐7) to 9 (95% CI: 8‐10), of which 2 (95% CI: 1‐2) to 3 (95% CI: 2‐4) were due to influenza. Up to 0.3% of the Romanian population were annually reported with ILI, and 0.01% was hospitalized with SARI, of which as much as one‐third could be explained by influenza. Conclusions This evaluation was the first study estimating influenza burden in Romania. We found that during each influenza season, a substantial number of persons in Romania suffer from influenza‐related ILI or are hospitalized due to influenza‐associated SARI.

We identified differences in the peripheral cellular immune response between mild and severe influenza. Our findings suggest that individuals with severe influenza may experience immune activation that, despite a slow start, is prolonged, compared with those with mild influenza. Abstract Background The immunologic factors underlying severe influenza are poorly understood. To address this, we compared the immune responses of influenza-confirmed hospitalized individuals with severe acute respiratory illness (SARI) to those of nonhospitalized individuals with influenza-like illness (ILI). Methods Peripheral blood lymphocytes were collected from 27 patients with ILI and 27 with SARI, at time of enrollment and then 2 weeks later. Innate and adaptive cellular immune responses were assessed by flow cytometry, and serum cytokine levels were assessed by a bead-based assay. Results During the acute phase, SARI was associated with significantly reduced numbers of circulating myeloid dendritic cells, CD192+ monocytes, and influenza virus–specific CD8+ and CD4+ T cells as compared to ILI. By the convalescent phase, however, most SARI cases displayed continued immune activation characterized by increased numbers of CD16+ monocytes and proliferating, and influenza virus–specific, CD8+ T cells as compared to ILI cases. SARI was also associated with reduced amounts of cytokines that regulate T-cell responses (ie, interleukin 4, interleukin 13, interleukin 12, interleukin 10, and tumor necrosis factor β) and hematopoiesis (interleukin 3 and granulocyte-macrophage colony-stimulating factor) but increased amounts of a proinflammatory cytokine (tumor necrosis factor α), chemotactic cytokines (MDC, MCP-1, GRO, and fractalkine), and growth-promoting cytokines (PDGFBB/AA, VEGF, and EGF) as compared to ILI. Conclusions Severe influenza cases showed a delay in the peripheral immune activation that likely led prolonged inflammation, compared with mild influenza cases.