Timing of influenza A(H5N1) in poultry and humans and seasonal influenza activity worldwide, 2004-2013.

Co-circulation of influenza A(H5N1) and seasonal influenza viruses among humans and animals could lead to co-infections, reassortment, and emergence of novel viruses with pandemic potential. We assessed the timing of subtype H5N1 outbreaks among poultry, human H5N1 cases, and human seasonal influenza in 8 countries that reported 97% of all human H5N1 cases and 90% of all poultry H5N1 outbreaks. In these countries, most outbreaks among poultry (7,001/11,331, 62%) and half of human cases (313/625, 50%) occurred during January-March. Human H5N1 cases occurred in 167 (45%) of 372 months during which outbreaks among poultry occurred, compared with 59 (10%) of 574 months that had no outbreaks among poultry. Human H5N1 cases also occurred in 59 (22%) of 267 months during seasonal influenza periods. To reduce risk for co-infection, surveillance and control of H5N1 should be enhanced during January-March, when H5N1 outbreaks typically occur and overlap with seasonal influenza virus circulation.

Modeling the effect of different vaccine effectiveness estimates on the number of vaccine-prevented influenza-associated hospitalizations in older adults.

We compared influenza vaccine-prevented hospitalizations in adults aged ≥65 years for a range of hypothetical effectiveness estimates. During 2012-2013, a vaccine with 10% effectiveness (66% coverage) would have averted approximately 13 000 hospitalizations, and a vaccine with 40% effectiveness would have averted approximately 60 000 hospitalizations. Annual vaccination is merited in this vulnerable population.

Explaining the link between access-to-care factors and health care resource utilization among individuals with COPD.

BACKGROUND: Limited accessibility to health care may be a barrier to obtaining good care. Few studies have investigated the association between access-to-care factors and COPD hospitalizations. The objective of this study is to estimate the association between access-to-care factors and health care utilization including hospital/emergency department (ED) visits and primary care physician (PCP) office visits among adults with COPD utilizing a nationally representative survey data. METHODS: We conducted a pooled cross-sectional analysis based upon a bivariate probit model, utilizing datasets from the 2011-2012 Behavioral Risk Factor Surveillance System linked with the 2014 Area Health Resource Files among adults with COPD. Dichotomous outcomes were hospital/ED visits and PCP office visits. Key covariates were county-level access-to-care factors, including the population-weighted numbers of pulmonary care specialists, PCPs, hospitals, rural health centers, and federally qualified health centers. RESULTS: Among a total of 9,332 observations, proportions of hospital/ED visits and PCP office visits were 16.2% and 44.2%, respectively. Results demonstrated that access-to-care factors were closely associated with hospital/ED visits. An additional pulmonary care specialist per 100,000 persons serves to reduce the likelihood of a hospital/ED visit by 0.4 percentage points (pp) (P=0.028). In contrast, an additional hospital per 100,000 persons increases the likelihood of hospital/ED visit by 0.8 pp (P=0.008). However, safety net facilities were not related to hospital utilizations. PCP office visits were not related to access-to-care factors. CONCLUSION: Pulmonary care specialist availability was a key factor in reducing hospital utilization among adults with COPD. The findings of our study implied that an increase in the availability of pulmonary care specialists may reduce hospital utilizations in counties with little or no access to pulmonary care specialists and that since availability of hospitals increases hospital utilization, directing patients with COPD to pulmonary care specialists may decrease hospital utilizations.

Cost-effectiveness of seasonal inactivated influenza vaccination among pregnant women.

OBJECTIVE: To evaluate the cost-effectiveness of seasonal inactivated influenza vaccination among pregnant women using data from three recent influenza seasons in the United States. DESIGN, SETTING, AND PARTICIPANTS: We developed a decision-analytic model following a cohort of 5.2 million pregnant women and their infants aged <6 months to evaluate the cost-effectiveness of vaccinating women against seasonal influenza during pregnancy from a societal perspective. The main outcome measures were quality-adjusted life-year (QALY) gained and cost-effectiveness ratios. Data sources included surveillance data, epidemiological studies, and published vaccine cost data. Sensitivity analyses were also performed. All costs and outcomes were discounted at 3% annually. MAIN OUTCOME MEASURES: Total costs (direct and indirect), effects (QALY gains, averted case numbers), and incremental cost-effectiveness of seasonal inactivated influenza vaccination among pregnant women (cost per QALY gained). RESULTS: Using a recent benchmark of 52.2% vaccination coverage among pregnant women, we studied a hypothetical cohort of 2,753,015 vaccinated pregnant women. With an estimated vaccine effectiveness of 73% among pregnant women and 63% among infants <6 months, QALY gains for each season were 305 (2010-2011), 123 (2011-2012), and 610 (2012-2013). Compared with no vaccination, seasonal influenza vaccination during pregnancy was cost-saving when using data from the 2010-2011 and 2012-2013 influenza seasons. The cost-effectiveness ratio was greater than $100,000/QALY with the 2011-2012 influenza season data, when CDC reported a low attack rate compared to other recent seasons. CONCLUSIONS: Influenza vaccination for pregnant women can reduce morbidity from influenza in both pregnant women and their infants aged <6 months. Seasonal influenza vaccination during pregnancy is cost-saving during moderate to severe influenza seasons.

Net Costs Due to Seasonal Influenza Vaccination--United States, 2005-2009.

BACKGROUND: Seasonal influenza causes considerable morbidity and mortality across all age groups, and influenza vaccination was recommended in 2010 for all persons aged 6 months and above. We estimated the averted costs due to influenza vaccination, taking into account the seasonal economic burden of the disease. METHODS: We used recently published values for averted outcomes due to influenza vaccination for influenza seasons 2005-06, 2006-07, 2007-08, and 2008-09, and age cohorts 6 months-4 years, 5-19 years, 20-64 years, and 65 years and above. Costs were calculated according to a payer and societal perspective (in 2009 US$), and took into account medical costs and productivity losses. RESULTS: When taking into account direct medical costs (payer perspective), influenza vaccination was cost saving only for the older age group (65≥) in seasons 2005-06 and 2007-08. Using the same perspective, influenza vaccination resulted in total costs of $US 1.7 billion (95%CI: $US 0.3-4.0 billion) in 2006-07 and $US 1.8 billion (95%CI: $US 0.1-4.1 billion) in 2008-09. When taking into account a societal perspective (and including the averted lost earnings due to premature death) averted deaths in the older age group influenced the results, resulting in cost savings for all ages combined in season 07-08. DISCUSSION: Influenza vaccination was cost saving in the older age group (65≥) when taking into account productivity losses and, in some seasons, when taking into account medical costs only. Averted costs vary significantly per season; however, in seasons where the averted burden of deaths is high in the older age group, averted productivity losses due to premature death tilt overall seasonal results towards savings. Indirect vaccination effects and the possibility of diminished case severity due to influenza vaccination were not considered, thus the averted burden due to influenza vaccine may be even greater than reported.

Deaths averted by influenza vaccination in the U.S. during the seasons 2005/06 through 2013/14.

BACKGROUND: Excess mortality due to seasonal influenza is substantial, yet quantitative estimates of the benefit of annual vaccination programs on influenza-associated mortality are lacking. METHODS: We estimated the numbers of deaths averted by vaccination in four age groups (0.5 to 4, 5 to 19, 20 to 64 and ≥65 yrs.) for the nine influenza seasons from 2005/6 through 2013/14. These estimates were obtained using a Monte Carlo approach applied to weekly U.S. age group-specific estimates of influenza-associated excess mortality, monthly vaccination coverage estimates and summary seasonal influenza vaccine effectiveness estimates to obtain estimates of the number of deaths averted by vaccination. The estimates are conservative as they do not include indirect vaccination effects. RESULTS: From August, 2005 through June, 2014, we estimated that 40,127 (95% confidence interval [CI] 25,694 to 59,210) deaths were averted by influenza vaccination. We found that of all studied seasons the most deaths were averted by influenza vaccination during the 2012/13 season (9398; 95% CI 2,386 to 19,897) and the fewest during the 2009/10 pandemic (222; 95% CI 79 to 347). Of all influenza-associated deaths averted, 88.9% (95% CI 83 to 92.5%) were in people ≥65 yrs. old. CONCLUSIONS: The estimated number of deaths averted by the US annual influenza vaccination program is considerable, especially among elderly adults and even when vaccine effectiveness is modest, such as in the 2012/13 season. As indirect effects ("herd immunity") of vaccination are ignored, these estimates represent lower bound estimates and are thus conservative given valid excess mortality estimates.