Severe Illnesses Associated With Outbreaks of Respiratory Syncytial Virus and Influenza in Adults.

BACKGROUND: Recent reports have described the contribution of adult respiratory syncytial virus (RSV) infections to the use of advanced healthcare resources and death. METHODS: Data regarding patients aged ≥18 years admitted to any of Maryland's 50 acute-care hospitals were evaluated over 12 consecutive years (2001-2013). We examined RSV and influenza (flu) surveillance data from the US National Respiratory and Enteric Virus Surveillance System and the Centers for Disease Control and Prevention and used this information to define RSV and flu outbreak periods in the Maryland area. Outbreak periods consisted of consecutive individual weeks during which at least 10% of RSV and/or flu diagnostic tests were positive. We examined relationships of RSV and flu outbreaks to occurrence of 4 advanced medical outcomes (hospitalization, intensive care unit admission, intubated mechanical ventilation, and death) due to medically attended acute respiratory illness (MAARI). RESULTS: Occurrences of all 4 MAARI-related hospital advanced medical outcomes were consistently greater for all adult ages during RSV, flu, and combined RSV-flu outbreak periods compared to nonoutbreak periods and tended to be greatest in adults aged ≥65 years during combined RSV-flu outbreak periods. Rate ratios for all 4 MAARI-related advanced medical outcomes ranged from 1.04 to 1.38 during the RSV, flu, or combined RSV-flu outbreaks compared to the nonoutbreak periods, with all 95% lower confidence limits >1. CONCLUSIONS: Both RSV and flu outbreaks were associated with surges in MAARI-related advanced medical outcomes (hospitalization, intensive care unit admission, intubated mechanical ventilation, and death) for adults of all ages.

Statin use and medically attended acute respiratory illness among influenza vaccine recipients.

BACKGROUND: Previous studies have suggested that statins decrease influenza vaccine effectiveness and increase risk of medically attended acute respiratory illness (MAARI). OBJECTIVES: To examine the association of incident statin use and MAARI in a cohort of influenza vaccine recipients. METHODS: This retrospective cohort study evaluated influenza vaccine recipients within the Tricare population. The primary outcome compared MAARI incidence during the follow-up period in a propensity score-matched cohort of incident statin users and statin non-users. Secondary analysis included propensity score-adjusted comparisons between incident statin users and statin non-users in the entire cohort and prespecified sub-cohorts with and without comorbidities. The propensity score was derived from 72 variables encompassing demographics, medical history, comorbidities, medication use, and healthcare utilization. RESULTS: MAARI incidence in statin users was similar to non-users in the propensity score-matched cohort (odds ratio [OR] 0.92; 95% confidence interval [CI] 0.84-1.01). In contrast, statin users with lower comorbidity had lower OR for MAARI compared to non-users (Charlson Score zero cohort: 0.85 [CI 0.74-0.98]; No Diabetes cohort: 0.88 [CI 0.80-0.96]). CONCLUSION: Incident statin use was not associated with increased MAARI incidence and may be associated with lower incidence of MAARI in those with less comorbidity. This study thus offers reassurance regarding the effectiveness of the influenza vaccine in statin users.

Hospitalization following outpatient medical care for influenza: US influenza vaccine effectiveness network, 2011-12-2015-16.

Over five seasons, we determined the proportion of outpatients with laboratory-confirmed, influenza-associated illness who were hospitalized within 30 days following the outpatient visit. Overall, 136 (1.7%) of 7813 influenza-positive patients were hospitalized a median of 4 days after an outpatient visit. Patients aged ≥ 65 years and those with high-risk conditions were at increased risk of hospitalization. After controlling for age and high-risk conditions, vaccination status and infecting influenza virus type were not associated with hospitalization risk among adults.

Effect of statin use on the risk of medically attended acute respiratory illness among influenza vaccinated elderly.

OBJECTIVES: The immunomodulatory effects of statins may reduce the immune response induced by influenza vaccines. However, evidence regarding the effect of statin use on the effectiveness of seasonal influenza vaccines against medically attended acute respiratory illness (MAARI) in the elderly remains scarce. METHODS: We conducted a retrospective cohort study using data from Taiwan's National Health Insurance Research Database. Elderly adults aged ≧ 66 years who were vaccinated with seasonal influenza vaccines during the 2007-2008 to 2012-2013 influenza seasons were enrolled for this analysis. We compared the risk of MAARI between statin and non-statin users. Propensity score matching and conditional logistic regression models were used to analyze the data. RESULTS: A total of 440,180 elderly were included in this study. In general, the risk of MAARI was higher in statin users than non-statin users (odds ratio [OR]: 1.03, 95% confidence interval [CI]: 1.02-1.05). Statin exposure after vaccination was associated with a higher risk of MAARI (OR: 1.05, 95% CI: 1.02-1.07). Among different statin agents, simvastatin and lovastatin use was associated with a significant increase in the risk of MAARI (ORsimvastatin: 1.14, 95% CI: 1.10-1.18; ORlovastatin: 1.18, 95% CI: 1.12-1.25). CONCLUSIONS: Statin exposure, especially simvastatin and lovastatin, was associated with a higher risk of MAARI in the seasonal influenza vaccinated elderly. Future studies exploring the differences between individual statins and mechanisms of their immunomodulatory effects are necessary.

Estimation of influenza-attributable medically attended acute respiratory illness by influenza type/subtype and age, Germany, 2001/02-2014/15.

BACKGROUND: The total burden of influenza in primary care is difficult to assess. The case definition of medically attended "acute respiratory infection" (MAARI) in the German physician sentinel is sensitive; however, it requires modelling techniques to derive estimates of disease attributable to influenza. We aimed to examine the impact of type/subtype and age. METHODS: Data on MAARI and virological results of respiratory samples (virological sentinel) were available from 2001/02 until 2014/15. We constructed a generalized additive regression model for the periodic baseline and the secular trend. The weekly number of influenza-positive samples represented influenza activity. In a second step, we distributed the estimated influenza-attributable MAARI (iMAARI) according to the distribution of types/subtypes in the virological sentinel. RESULTS: Season-specific iMAARI ranged from 0.7% to 8.9% of the population. Seasons with the strongest impact were dominated by A(H3), and iMAARI attack rate of the pandemic 2009 (A(H1)pdm09) was 4.9%. Regularly the two child age groups (0-4 and 5-14 years old) had the highest iMAARI attack rates reaching frequently levels up to 15%-20%. Influenza B affected the age group of 5- to 14-year-old children substantially more than any other age group. Sensitivity analyses demonstrated both comparability and stability of the model. CONCLUSION: We constructed a model that is well suited to estimate the substantial impact of influenza on the primary care sector. A(H3) causes overall the greatest number of iMAARI, and influenza B has the greatest impact on school-age children. The model may incorporate time series of other pathogens as they become available.

Illness Severity and Work Productivity Loss Among Working Adults With Medically Attended Acute Respiratory Illnesses: US Influenza Vaccine Effectiveness Network 2012-2013.

BACKGROUND: Influenza causes significant morbidity and mortality, with considerable economic costs, including lost work productivity. Influenza vaccines may reduce the economic burden through primary prevention of influenza and reduction in illness severity. METHODS: We examined illness severity and work productivity loss among working adults with medically attended acute respiratory illnesses and compared outcomes for subjects with and without laboratory-confirmed influenza and by influenza vaccination status among subjects with influenza during the 2012-2013 influenza season. RESULTS: Illnesses laboratory-confirmed as influenza (ie, cases) were subjectively assessed as more severe than illnesses not caused by influenza (ie, noncases) based on multiple measures, including current health status at study enrollment (≤7 days from illness onset) and current activity and sleep quality status relative to usual. Influenza cases reported missing 45% more work hours (20.5 vs 15.0; P < .001) than noncases and subjectively assessed their work productivity as impeded to a greater degree (6.0 vs 5.4; P < .001). Current health status and current activity relative to usual were subjectively assessed as modestly but significantly better for vaccinated cases compared with unvaccinated cases; however, no significant modifications of sleep quality, missed work hours, or work productivity loss were noted for vaccinated subjects. CONCLUSIONS: Influenza illnesses were more severe and resulted in more missed work hours and productivity loss than illnesses not confirmed as influenza. Modest reductions in illness severity for vaccinated cases were observed. These findings highlight the burden of influenza illnesses and illustrate the importance of laboratory confirmation of influenza outcomes in evaluations of vaccine effectiveness.

Impact of Statins on Influenza Vaccine Effectiveness Against Medically Attended Acute Respiratory Illness.

BACKGROUND: Statins have antiinflammatory effects that may impact vaccine-induced immune responses. We investigated the impact of statin therapy on influenza vaccine effectiveness (VE) against medically attended acute respiratory illness (MAARI). METHODS: We conducted a retrospective cohort study over nine influenza seasons using research databases of a large managed care organization in the United States. Influenza vaccination and statin prescription statuses of cohort members and MAARI cases were ascertained on a per-season basis. Incidence rate ratios (IRRs) of MAARI were estimated using Poisson regression and stratified by statin use. Using a ratio of ratios approach, we compared IRRs from periods during to IRRs from periods before influenza circulation and then used relative IRRs to compute VE. RESULTS: After adjustment for multiple prespecified covariates, the influenza VE against MAARI was lower among statin users than nonusers during periods of local (14.1% vs 22.9%; mean difference, 11.4%; 95% confidence interval [CI], -1.7% to 26.1%) and widespread (12.6% vs 26.2%; mean difference, 18.4%; 95% CI, 2.9%-36.2%) influenza circulation. CONCLUSIONS: In this study, statin therapy was associated with reduced influenza VE against MAARI. Since many cases of MAARI are not caused by influenza, studies of the impact of statins on influenza VE against laboratory-confirmed influenza are needed.

Surge in Hospitalizations Associated With Mechanical Ventilator Use During Influenza Outbreaks.

OBJECTIVE: Information on surges in critical care services including mechanical ventilator use during seasonal influenza outbreaks is limited. To potentially facilitate preparedness plans for future pandemics, we retrospectively quantitated surges in all-cause mechanical ventilator use during peak influenza for 12 consecutive years in all certified hospitals in Maryland. METHODS: Influenza testing data obtained for the Centers for Disease Control and Protection, Health and Human Services region 3, included defined peak influenza outbreak periods (PIOP), non-influenza time periods (non-ITP), and proportions of circulating influenza types for all study years. Procedure codes for mechanical ventilator use and diagnostic codes for medically attended acute respiratory illness (MAARI) were reviewed for every Maryland hospitalization. Daily counts of hospitalizations associated with ventilator use or MAARI during PIOP compared to non-ITP were analyzed using Poisson regression adjusted for month and year. RESULTS: Ventilator use increased during PIOP by 7% (95% CI, 5-10) over non-ITP (P < .0001) for all study years. These annual surges correlated with influenza season intensity, as measured by MAARI-related hospitalizations (correlation coefficient = 0.91, P < .0001). CONCLUSIONS: Surges in ventilator use were temporally associated with PIOP and were positively correlated with influenza season intensity, as measured by hospitalizations associated with acute respiratory illness. This information may assist resource planning for future pandemics. (Disaster Med Public Health Preparedness. 2014;x:1-7).