Facemasks and hand hygiene to prevent influenza transmission in households: a cluster randomized trial.
BACKGROUND
Few data are available about the effectiveness of nonpharmaceutical interventions for preventing influenza virus transmission.


OBJECTIVE
To investigate whether hand hygiene and use of facemasks prevents household transmission of influenza.


METHODS
Cluster randomized, controlled trial. Randomization was computer generated; allocation was concealed from treating physicians and clinics and implemented by study nurses at the time of the initial household visit. Participants and personnel administering the interventions were not blinded to group assignment. (ClinicalTrials.gov registration number: NCT00425893)


METHODS
Households in Hong Kong.


METHODS
407 people presenting to outpatient clinics with influenza-like illness who were positive for influenza A or B virus by rapid testing (index patients) and 794 household members (contacts) in 259 households.


METHODS
Lifestyle education (control) (134 households), hand hygiene (136 households), or surgical facemasks plus hand hygiene (137 households) for all household members.


METHODS
Influenza virus infection in contacts, as confirmed by reverse-transcription polymerase chain reaction (RT-PCR) or diagnosed clinically after 7 days.


RESULTS
Sixty (8%) contacts in the 259 households had RT-PCR-confirmed influenza virus infection in the 7 days after intervention. Hand hygiene with or without facemasks seemed to reduce influenza transmission, but the differences compared with the control group were not significant. In 154 households in which interventions were implemented within 36 hours of symptom onset in the index patient, transmission of RT-PCR-confirmed infection seemed reduced, an effect attributable to fewer infections among participants using facemasks plus hand hygiene (adjusted odds ratio, 0.33 [95% CI, 0.13 to 0.87]). Adherence to interventions varied.


CONCLUSIONS
The delay from index patient symptom onset to intervention and variable adherence may have mitigated intervention effectiveness.


CONCLUSIONS
Hand hygiene and facemasks seemed to prevent household transmission of influenza virus when implemented within 36 hours of index patient symptom onset. These findings suggest that nonpharmaceutical interventions are important for mitigation of pandemic and interpandemic influenza.


BACKGROUND
Centers for Disease Control and Prevention.
Cowling
Benjamin J
BJ
School of Public Health and University of Hong Kong, Cyberport 3, Pokfulam, Hong Kong SAR. bcowling@hku.hk
Chan
Kwok-Hung
KH
Fang
Vicky J
VJ
Cheng
Calvin K Y
CK
Fung
Rita O P
RO
Wai
Winnie
W
Sin
Joey
J
Seto
Wing Hong
WH
Yung
Raymond
R
Chu
Daniel W S
DW
Chiu
Billy C F
BC
Lee
Paco W Y
PW
Chiu
Ming Chi
MC
Lee
Hoi Che
HC
Uyeki
Timothy M
TM
Houck
Peter M
PM
Peiris
J S Malik
JS
Leung
Gabriel M
GM
D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005191:Family Characteristics; D006235:Hand Disinfection; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D009980:Influenza A virus / Q000302:isolation & purification; D009981:Influenza B virus / Q000302:isolation & purification; D007251:Influenza, Human / Q000175:diagnosis / Q000517:prevention & control* / Q000635:transmission; D008297:Male; D008397:Masks; D008875:Middle Aged; D010349:Patient Compliance; D010353:Patient Education as Topic; D011446:Prospective Studies; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012307:Risk Factors; D013997:Time Factors; D055815:Young Adult