***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: Please cite this paper as : MacIntyre et al. ( 2011 ) A cluster r and omized clinical trial comparing fit‐tested and non‐fit‐tested  N95 respirators to medical masks to prevent respiratory virus infection in health care workers . Influenza and Other Respiratory Viruses DOI : 10.1111/j.1750‐2659.2010.00198.x . Background We compared the efficacy of medical masks , N95 respirators ( fit tested and non fit tested ) , in health care workers ( HCWs ) . Methods A cluster r and omized clinical trial ( RCT ) of 1441 HCWs in 15 Beijing hospitals was performed during the 2008/2009 winter . Participants wore masks or respirators  during the entire work shift for 4 weeks . Outcomes included clinical respiratory illness ( CRI ) , influenza‐like illness ( ILI ) , laboratory‐confirmed respiratory virus infection and influenza . A convenience no‐mask/respirator group of 481 health workers from nine hospitals was compared . Findings The rates of CRI ( 3·9 % versus 6·7 % ) , ILI ( 0·3 % versus 0·6 % ) , laboratory‐confirmed respiratory virus ( 1·4 % versus 2·6 % ) and influenza ( 0·3 % versus 1 % ) infection were consistently lower for the N95 group compared to medical masks . By intention‐to‐treat analysis , when P values were adjusted for clustering , non‐fit‐tested N95 respirators were significantly more protective than medical masks against CRI , but no other outcomes were significant . The rates of all outcomes were higher in the convenience no‐mask group compared to the intervention arms . There was no significant difference in outcomes between the N95 arms with and without fit testing . Rates of fit test failure were low . In a post hoc analysis adjusted for potential confounders , N95 masks and hospital level were significant , but medical masks , vaccination , h and washing and high‐risk procedures were not . Interpretation Rates of infection in the medical mask group were double that in the N95 group . A benefit of respirators is suggested but would need to be confirmed by a larger trial , as this study may have been underpowered . The finding on fit testing is specific to the type of respirator used in the study and can not be generalized to other respirators . Trial registration Australian New Zeal and Clinical Trials Registry ( ANZCTR ) , ACTRN : ACTRN12609000257268 ( http://www.anzctr.org.au ) Please cite this paper as : Simmerman et al. ( 2011 ) Findings from a household r and omized controlled trial of h and washing and face masks to reduce influenza transmission in Bangkok , Thail and . Influenza and Other Respiratory Viruses 5(4 ) , 256–267 Background Evidence is needed on the effectiveness of non‐pharmaceutical interventions ( NPIs ) to reduce influenza transmission . Methodology We studied NPIs in households with a febrile , influenza‐positive child . Households were r and omized to control , h and washing ( HW ) , or h and washing plus paper surgical face masks ( HW + FM ) arms . Study nurses conducted home visits within 24 hours of enrollment and on days 3 , 7 , and 21 . Respiratory swabs and serum were collected from all household members and tested for influenza by RT‐PCR or serology . Principal Findings Between April 2008 and August 2009 , 991 ( 16·5 % ) of 5995 pediatric influenza‐like illness patients tested influenza positive . Four hundred and forty‐two index children with 1147 household members were enrolled , and 221 ( 50·0 % ) were aged < 6 years . Three hundred and ninety‐seven ( 89·8 % ) households reported that the index patient slept in the parents ’ bedroom . The secondary attack rate was 21·5 % , and 56/345 ( 16·3 % ; 95 % CI 12·4–20·2 % ) secondary cases were asymptomatic . H and ‐washing subjects reported 4·7 washing episodes/day , compared to 4·9 times/day in the HW + FM arm and 3·9 times/day in controls ( P = 0·001 ) . The odds ratios ( ORs ) for secondary influenza infection were not significantly different in the HW arm ( OR = 1·20 ; 95 % CI 0·76–1·88 ; P‐0.442 ) , or the HW + FM arm ( OR = 1·16 ; 95 % CI .0·74–1·82 ; P = 0.525 ) . Conclusions Influenza transmission was not reduced by interventions to promote h and washing and face mask use . This may be attributable to transmission that occurred before the intervention , poor facemask compliance , little difference in h and ‐washing frequency between study groups , and shared sleeping arrangements . A prospect i ve study design and a careful analysis of sociocultural factors could improve future NPI studies Rationale Medical masks are commonly used by sick individuals with influenza-like illness ( ILI ) to prevent spread of infections to others , but clinical efficacy data are absent . Objective Determine whether medical mask use by sick individuals with ILI protects well contacts from related respiratory infections . Setting 6 major hospitals in 2 districts of Beijing , China . Design Cluster r and omised controlled trial . Participants 245 index cases with ILI . Intervention Index cases with ILI were r and omly allocated to medical mask ( n=123 ) and control arms ( n=122 ) . Since 43 index cases in the control arm also used a mask during the study period , an as-treated post hoc analysis was performed by comparing outcomes among household members of index cases who used a mask ( mask group ) with household members of index cases who did not use a mask ( no-mask group ) . Main outcome measure Primary outcomes measured in household members were clinical respiratory illness , ILI and laboratory-confirmed viral respiratory infection . Results In an intention-to-treat analysis , rates of clinical respiratory illness ( relative risk ( RR ) 0.61 , 95 % CI 0.18 to 2.13 ) , ILI ( RR 0.32 , 95 % CI 0.03 to 3.13 ) and laboratory-confirmed viral infections ( RR 0.97 , 95 % CI 0.06 to 15.54 ) were consistently lower in the mask arm compared with control , although not statistically significant . A post hoc comparison between the mask versus no-mask groups showed a protective effect against clinical respiratory illness , but not against ILI and laboratory-confirmed viral respiratory infections . Conclusions The study indicates a potential benefit of medical masks for source control , but is limited by small sample size and low secondary attack rates . Larger trials are needed to confirm efficacy of medical masks as source control . Trial registration number ACTRN12613000852752 ; Results Abstract Objective We compared the efficacy of medical masks ( MM ) and N95 respirators ( N95 ) in preventing bacterial colonization/infection in healthcare workers ( HCWs ) . Methods A cluster r and omized clinical trial ( RCT ) of 1441 hospital HCWs r and omized to medical masks or N95 respirators , and compared to 481 control HCWs , was performed in Beijing , China , during the winter season of 2008–2009 . Participants were followed for development of clinical respiratory illness ( CRI ) . Symptomatic subjects were tested for Streptococcus pneumoniae , Bordetella pertussis , Chlamydia pneumoniae , Mycoplasma pneumoniae or Haemophilus influenza type B by multiplex polymerase chain reaction ( PCR ) . Results The rate of bacterial colonization was 2.8 % in the N95 group ( p=0.02 ) , 5.3 % among medical mask users ( p<0.01 ) and 7.5 % among the controls ( p=0.16 ) . N95 respirators were significantly protective ( adjusted RR 0.34 , 95 % CI : 0.21–0.56 ) against bacterial colonization . Co-infections of two bacteria or a virus and bacteria occurred in up to 3.7 % of HCWs , and were significantly lower in the N95 arm . Conclusions N95 respirators were significantly protective against bacterial colonization , co-colonization and viral-bacterial co-infection . We showed that dual respiratory virus or bacterial-viral co-infections can be reduced by the use of N95 respirators . This study has occupational health and safety implication s for health workers BACKGROUND During the influenza A(H1N1 ) p and emic , antiviral prescribing was limited , vaccines were not available early , and the effectiveness of nonpharmaceutical interventions ( NPIs ) was uncertain . Our study examined whether use of face masks and h and hygiene reduced the incidence of influenza-like illness ( ILI ) . METHODS A r and omized intervention trial involving 1437 young adults living in university residence halls during the 2006 - 2007 influenza season was design ed . Residence halls were r and omly assigned to 1 of 3 groups-face mask use , face masks with h and hygiene , or control- for 6 weeks . Generalized models estimated rate ratios for clinical ly diagnosed or survey-reported ILI weekly and cumulatively . RESULTS We observed significant reductions in ILI during weeks 4 - 6 in the mask and h and hygiene group , compared with the control group , ranging from 35 % ( confidence interval [ CI ] , 9%-53 % ) to 51 % ( CI , 13%-73 % ) , after adjusting for vaccination and other covariates . Face mask use alone showed a similar reduction in ILI compared with the control group , but adjusted estimates were not statistically significant . Neither face mask use and h and hygiene nor face mask use alone was associated with a significant reduction in the rate of ILI cumulatively . CONCLUSIONS These findings suggest that face masks and h and hygiene may reduce respiratory illnesses in shared living setting s and mitigate the impact of the influenza A(H1N1 ) p and emic . TRIAL REGISTRATION Clinical Trials.gov identifier : NCT00490633 Introduction While influenza A and B viruses can be transmitted via respiratory droplets , the importance of small droplet nuclei “ aerosols ” in transmission is controversial . Methods and Findings In Hong Kong and Bangkok , in 2008–11 , subjects were recruited from outpatient clinics if they had recent onset of acute respiratory illness and none of their household contacts were ill . Following a positive rapid influenza diagnostic test result , subjects were r and omly allocated to one of three household-based interventions : h and hygiene , h and hygiene plus face masks , and a control group . Index cases plus their household contacts were followed for 7–10 days to identify secondary infections by reverse transcription polymerase chain reaction ( RT-PCR ) testing of respiratory specimens . Index cases with RT-PCR-confirmed influenza B were included in the present analyses . We used a mathematical model to make inferences on the modes of transmission , facilitated by apparent differences in clinical presentation of secondary infections result ing from aerosol transmission . We estimated that approximately 37 % and 26 % of influenza B virus transmission was via the aerosol mode in households in Hong Kong and Bangkok , respectively . In the fitted model , influenza B virus infections were associated with a 56%–72 % risk of fever plus cough if infected via aerosol route , and a 23%–31 % risk of fever plus cough if infected via the other two modes of transmission . Conclusions Aerosol transmission may be an important mode of spread of influenza B virus . The point estimates of aerosol transmission were slightly lower for influenza B virus compared to previously published estimates for influenza A virus in both Hong Kong and Bangkok . Caution should be taken in interpreting these findings because of the multiple assumptions inherent in the model , including that there is limited biological evidence to date supporting a difference in the clinical features of influenza B virus infection by different modes BACKGROUND Health care workers outside surgical suites in Asia use surgical-type face masks commonly . Prevention of upper respiratory infection is one reason given , although evidence of effectiveness is lacking . METHODS Health care workers in a tertiary care hospital in Japan were r and omized into 2 groups : 1 that wore face masks and 1 that did not . They provided information about demographics , health habits , and quality of life . Participants recorded symptoms daily for 77 consecutive days , starting in January 2008 . Presence of a cold was determined based on a previously vali date d measure of self-reported symptoms . The number of colds between groups was compared , as were risk factors for experiencing cold symptoms . RESULTS Thirty-two health care workers completed the study , result ing in 2464 subject days . There were 2 colds during this time period , 1 in each group . Of the 8 symptoms recorded daily , subjects in the mask group were significantly more likely to experience headache during the study period ( P < .05 ) . Subjects living with children were more likely to have high cold severity scores over the course of the study . CONCLUSION Face mask use in health care workers has not been demonstrated to provide benefit in terms of cold symptoms or getting colds . A larger study is needed to definitively establish noninferiority 
    Output:
    
Conclusion The use of N95 respirators compared with surgical masks is not associated with a lower risk of laboratory‐confirmed influenza .
It suggests that N95 respirators should not be recommended for general public and nonhigh‐risk medical staff those are not in close contact with influenza patients or suspected patients