Surgical Mask Prophylaxis during Osculation: The Impact of Variable Lingual Muscle Thrusting. (2009) M. Besos, A. Lothario, and G. Cassanova. Emerging Infectious Diseases.
Human to human spread of influenza is known to be particularly efficient at educational institutions. Although substantial evidence has shown that the best way to limit the spread of pandemic influenza is early and complete school closures, current CDC policy requires that schools remain open as long as possible. Given this policy, it is important to explore the effectiveness of various mitigation strategies in educational institutions. Colleges pose particular problems as the presence of large numbers young people with peak reproductive steroid production oftentimes results in significant bodily fluid exchange. As saliva swapping is a known risk factor for influenza dissemination, we explored the potential of surgical mask prophylaxis to decrease the R0 among college-age humans.
Two groups, one which wore surgical masks during osculation and one which did not, were compared with respect to influenza dissemination. The two groups were matched for age, steroid hormone level and attractiveness. Of note, although 30 matched pairs were part of the original study design, N = 10 for the matched pairs due to insufficient numbers of female subjects. Interestingly, over 1,000 males had signed up for the experiment. The reason for this sex disparity in recruitment is unclear to us, but will be the subject of a future study.
In each group, one half of each matched pair, randomly chosen, was intranasaly innoculated with the H1N1 pandemic virus. IRB approval was based on the CDC finding that this virus is no more virulent than seasonal flu.
Based on a pilot project, force tensiometers were wired to each participants lingual muscle to determine the impact of thrusting force on prophylaxis.
In both groups, all individuals presented with clinical signs of infection. Symptoms included cough (70%), fever (60%), sore throat (55%), diarrhea (40%) and vomiting (36%). Three of the subjects in the control group and two in the experimental group unexpectedly became ill and needed to hospitalised. Two of the subjects required ventilation and one died. A thorough investigation revealed no breach of CDC approved protocols. 50% of the subjects were positive with Flu A tests. 100% of subjects were positive with RT-PCR assays.
One interesting finding from the current study was that our instrument for lingual thrusting force proved quite effective. A t-test indicated a significant difference between males and females in lingual thrusting force (p<0.001). However, we should note that the experiment was not carried to completion in 6 of the matched pairs as the males in these groups removed their own and their female partners surgical masks after less than 3 minutes of osculation. Post-osculation analysis indicates that the masks were removed with unnecessary force suggesting that future designs factor in more robust ear loops.
Although the current results indicate some limitations to the use of surgical masks as prophylaxis for college students during the ongoing H1N1 pandemic, the effectiveness of the tensiometers for measuring lingual thrusting force is encouraging. Additional studies are necessary to understand the psychological factors influencing premature prophylaxis removal.
The expert advice of Baiser Langoureux in study design is gratefully acknowledged.