***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: The risk factors for complications in patients with influenza A (H1N1)v virus infection have not been fully eluci date d. We performed an observational analysis of a prospect i ve cohort of hospitalized adults with confirmed p and emic influenza A (H1N1)v virus infection at 13 hospitals in Spain , between June 12 and November 10 , 2009 , to identify factors associated with severe disease . Severe disease was defined as the composite outcome of intensive-care unit ( ICU ) admission or in-hospital mortality . During the study period , 585 adult patients ( median age 40 years ) required hospitalization because of p and emic ( H1N1 ) 2009 . At least one comorbid condition was present in 318 ( 54.4 % ) patients .  Pneumonia was diagnosed in 234 ( 43.2 % ) patients and bacterial co-infection in 45 ( 7.6 % ) . Severe disease occurred in 75 ( 12.8 % ) patients , of whom 71 required ICU admission and 13 ( 2.2 % ) died . Independent factors for severe disease were age < 50 years ( OR , 2.39 ; 95 % CI , 1.05 - 5.47 ) , chronic comorbid conditions ( OR , 2.93 ; 95 % CI , 1.41 - 6.09 ) , morbid obesity ( OR , 6.7 ; 95 % CI , 2.25 - 20.19 ) , concomitant and secondary bacterial co-infection ( OR , 2.78 ; 95 % CI , 1.11 - 7 ) and early oseltamivir therapy ( OR , 0.32 ; 95 % CI 0.16 - 0.63 ) . In conclusion , although adults hospitalized for p and emic ( H1N1 ) 2009 suffer from significant morbidity , mortality is lower than that reported in the earliest studies . Younger age , chronic comorbid conditions , morbid obesity and bacterial co-infection are independent risk factors for severe disease , whereas early oseltamivir therapy is a protective factor OBJECTIVE To compare the effectiveness of zanamivir with oseltamivir for influenza A and B. METHODS 1113 patients with influenza A or B were enrolled in the 2006 - 2007 influenza season . The duration of fever ( temperature , > or=37.5 degrees C ) and the percentage of patients afebrile at 24 and 48 h after the first dose of zanamivir or oseltamivir  were calculated . Virus persistence after zanamivir therapy was also evaluated . RESULTS There were marginally significant differences between the duration of fever after the first dose of zanamivir ( 31.8+/-18.4h ) and oseltamivir ( 35.5+/-23.9h ) for influenza A ( p<0.05 ) . The duration of fever after starting zanamivir therapy ( 35.8+/-22.4h ) was significantly shorter than that of oseltamivir ( 52.7+/-31.3h ) for influenza B ( p<0.001 ) . There were no significant differences between influenza A and B in the percentage of patients afebrile at 24 or 48 h after the first inhalation of zanamivir . The reisolation rate after zanamivir  therapy showed marginally significant differences between influenza A and B ( < 0.05 ) . By multiple regression analysis , therapy ( zanamivir or oseltamivir ) was the major determinant affecting the duration of fever for influenza B. CONCLUSION Zanamivir therapy is more effective than oseltamivir for the treatment of influenza B infection Background —Influenza infection has been associated with increased risk of adverse cardiac and cerebral vascular outcomes .  Oseltamivir , a treatment for influenza , has been shown to decrease the severity of an influenza episode , but few data exist regarding its potentially protective effect against recurrent vascular outcomes among influenza patients with a history of vascular disease . Methods and Results —Electronic healthcare service and pharmacy records for 37 482 TRICARE beneficiaries , aged 18 and older , with a coded history of cardiovascular ( CV ) disease and a subsequent diagnosis of influenza from October 1 , 2003 , through September 30 , 2007 , were examined . Subjects were grouped according to whether they had filled a prescription for oseltamivir within 2 days of their influenza diagnosis . The incidence of recurrent CV events within 30 days after the influenza diagnosis among oseltavmivir-treated and untreated subjects was 8.5 % and 21.2 % , respectively ( P<0.005 ) . Subject age was a persistent and significant contributor to the likelihood of recurrent CV outcomes . After controlling for the differences in demographics among treated and untreated cohorts using a propensity-scored logistic regression model , a statistically significant protective effect was associated with oseltamivir treatment ( odds ratio , 0.417 ; 95 % CI , 0.349 to 0.498 ) . Conclusions —Our findings suggests that oseltamivir treatment for influenza is associated with significant decrease in the risk of recurrent CV events in subjects with a history of CV disease . These findings merit confirmation in further prospect i ve and controlled studies . Meanwhile , in patients with CV disease , strict adherence with current practice guidelines for prevention and treatment of influenza is recommended BACKGROUND In April 2009 a novel influenza A virus ( AH1N1v ) of swine origin ( swine flu ) emerged , spreading rapidly and achieving p and emic status in June 2009 . Pregnant women were identified as being at high risk of severe influenza-related complications and as a priority group for vaccination against AH1N1v . Limited information was available about the maternal and fetal risks of AH1N1v infection or of antiviral drug or AH1N1v vaccine use in pregnancy . OBJECTIVES To assess rates of and risk factors for adverse outcomes following AH1N1v infection in pregnancy and to assess the adverse effects of the antiviral drugs and vaccines used in prevention and management . METHODS Prospect i ve national cohort studies were conducted to identify pregnant women who were ( 1 ) suspected to be infected with AH1N1v or being treated with antiviral medication in primary care ; ( 2 ) vaccinated against AH1N1v ; and ( 3 ) admitted to hospital with confirmed AH1N1v . Characteristics of women with influenza-like illness ( ILI ) in primary care were compared with those of women without symptoms accepting or declining immunisation . Characteristics of women admitted to hospital with confirmed AH1N1v infection in pregnancy were compared with a historical cohort of over 1200 women giving birth in the UK who were uninfected with AH1N1v . Outcomes examined in hospitalised women included maternal death , admission to an intensive care unit , perinatal mortality and preterm birth . Risk factors for hospital and intensive care unit admission were examined in a full regression model . RESULTS The weekly incidence of ILI among pregnant women averaged 51/100,000 over the study period .  Antiviral drugs were offered to 4.8 % [ 95 % confidence interval ( CI ) 4.0 % to 5.9 % ] and vaccination to 64.8 % ( 95 % CI 64.7 % to 68.9 % ) of registered pregnant women . Ninety pregnant women with ILI presenting in primary care were reported to the research team , 55 of whom were prescribed antiviral drugs and in 42 ( 76 % ) cases this was within 2 days of symptom onset . After comparison with 1329 uninfected pregnant women offered vaccination , pre-existing asthma was the only maternal factor identified as increasing risk of ILI presentation [ adjusted odds ratio ( OR ) 2.0 , 95 % CI 1.0 to 3.9 ] . Maternal obesity and smoking during pregnancy were also associated with hospital admission with AH1N1v infection . Overall , 241 pregnant women were admitted to hospital with laboratory-confirmed AH1N1v infection . Eighty-three per cent of these women were treated with antiviral agents , but only 6 % received antiviral treatment before hospital admission . Treatment within 2 days of symptom onset was associated with an 84 % reduction in the odds of admission to an intensive therapy unit ( OR 0.16 , 95 % CI 0.08 to 0.34 ) . Women admitted to hospital with AH1N1v infection were more likely to deliver preterm ; a three times increased risk was suggested compared with an uninfected population cohort ( OR 3.1 , 95 % CI 2.1 to 4.5 ) . CONCLUSIONS Earlier treatment with antiviral agents is associated with improved outcomes for pregnant women and further actions are needed in future p and emics to ensure that antiviral agents and vaccines are provided promptly to pregnant women , particularly in the primary care setting . Further research is needed on longer-term outcomes for infants exposed to AH1N1v influenza , antiviral drugs or vaccines during pregnancy Background The aim of this study was to investigate factors affecting clinical outcomes of adults hospitalised with severe seasonal influenza . Methods A prospect i ve , observational cohort study was conducted over 24 months ( 2007–2008 ) in two acute , general hospitals . Consecutive , hospitalised adult patients were recruited and followed once their laboratory diagnosis of influenza A/B was established ( based on viral antigen detection and virus isolation from nasopharyngeal aspirates collected per protocol ) . Outcomes studied included in-hospital death , length of stay and duration of oxygen therapy . Factors affecting outcomes were analysed using multivariate Cox proportional hazards models . Sequencing analysis on the neuraminidase gene was performed for available H1N1 isolates . Results 754 patients were studied ( influenza A , n=539 ; > 75 % H3N2 ) . Their mean age was 70±18 years ; co-morbidities and serious complications were common ( 61–77 % ) . Supplemental oxygen and ventilatory support was required in 401 ( 53.2 % ) and 41 ( 5.4 % ) patients , respectively . 39 ( 5.2 % ) patients died ; pneumonia , respiratory failure and sepsis were the causes . 395 ( 52 % ) patients received antiviral ( oseltamivir ) treatment . Omission of antiviral treatment was associated with delayed presentation or negative antigen detection results . The mortality rate was 4.56 and 7.42 per 1000 patient-days in the treated and untreated patients , respectively ; among those with co-morbidities , it was 5.62 and 11.64 per 1000 patient-days , respectively . In multivariate analysis , antiviral use was associated with reduced risk of death ( adjusted HR ( aHR ) 0.27 ( 95 % CI 0.13 to 0.55 ) ; p<0.001 ) . Improved survival was observed with treatment started within 4 days from onset . Earlier hospital discharge ( aHR 1.28 ( 95 % CI 1.04 to 1.57 ) ; p=0.019 ) and faster discontinuation of oxygen therapy ( aHR 1.30 ( 95 % CI 1.01 to 1.69 ) ; p=0.043 ) was associated with early treatment within 2 days . Few ( n=15 ) H1N1 isolates in this cohort had the H275Y mutation . Conclusions Antiviral treatment for severe influenza is associated with reduced mortality and improved clinical outcomes Oseltamivir has been used for treatment of influenza A and B infections , but recent reports documented that it was less active against the latter . We compared the effectiveness of oseltamivir in children between laboratory confirmed influenza A and B over 4 influenza seasons from 2001 to 2005 in a pediatric clinic in Japan . Among 1,848 patients screened , 299 influenza A and 209 influenza B patients were administered oseltamivir  ( treated groups ) , and 28 influenza A and 66 influenza B patients were assigned as non-treated groups . The duration of fever , defined as period when patients had the maximum temperature higher than 37.5 degrees C in three-time measurements in a day after the clinic visit , was evaluated among the four groups . In uni-variate analysis , the duration of fever was shorter for treated group than non-treated for influenza A ( 1.8 + /- 0.9 days vs 2.6 + /- 1.3 days , p < 0.01 ) , but it was not significant for influenza B ( 2.4 + /- 1.3 days vs 2.8 + /- 1.2 days , p = 0.9 ) . The fever duration was longer in treated influenza B than A patients ( p < 0.01 ) . Multi-variate analysis indicated younger age ( < 6 years old ) and higher body temperature at the clinic visit prolonged the duration of fever . Adjusted average duration of fever indicated that oseltamivir was effective for both types , but more effective on influenza A , and the benefit increased for younger children . Our data provide evidence that oseltamivir is beneficial for influenza infections , but the effectiveness is differed by type and age BACKGROUND To compare the effectiveness of oseltamivir for treatment of influenza 
    Output:
    
Earlier treatment with oseltamivir was generally associated with better outcomes .
Direct comparison of oral oseltamivir and inhaled zanamivir suggests no important differences in key outcomes .
Therapy with oral oseltamivir and inhaled zanamivir may provide a net benefit over no treatment of influenza .