Transocular Entry of Seasonal Influenza-Attenuated Virus Aerosols and the Efficacy of N95 Respirators, Surgical Masks, and Eye Protection in Humans

Background. The efficacy of barrier precautions to prevent influenza transmission is unknown. Methods. Twenty-eight participants were exposed to monodispersed live attenuated influenza vaccine (LAIV) particles (4.9 mu m) in 6 groups: group 1, no precautions; group 2, ocular exposure only; group 3, surgical mask without eye protection; group 4, surgical mask with eye protection; group 5, fit-tested N95 respirator without eye protection; and group 6, fit-tested N95 respirator with eye protection. Influenza was detected by reverse-transcription polymerase chain reaction (RT-PCR) and culture in nasal washes. Exact 95% confidence intervals (CIs) were calculated. Results. Influenza was detected in 4 of 4 participants in group 1 (95% CI, 0-.60), 3 of 4 in group 2 (95% CI, .006-.806]), 5 of 5 in group 3 (95% CI, 0-.522), 5 of 5 in group 4, (95% CI, 0-.522), 3 of 5 in group 5 (95% CI, .053-.853), and 1 of 5 in group 6 (95% CI, .05-.72). RT-PCR revealed significant differences between group 1 and all other groups except group 3. Conclusions. Transocular transmission of LAIV occured in most participants suggesting the necessity of eye protection. An N95 respirator provided the best guard further enhanced by eye protection.