We are entering a period of deconfinement linked to Covid-19. Much progress has been made in a few weeks on the understanding of Sars-CoV2. However, there many questions remain, notably relating to duration and quality of immunity acquired following an infection, or efficacy of vaccines under development… and finally on the best strategy for combating Covid-19.

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We have been imposed protective though imperfect measures. They aim at reducing risks of spreading infection. Social distancing is not always well respected, most masks offer imperfect protection, even more so during summertime. There are no vaccines yet available that have been proven to be effective.

Viruses existed long before the dawn of humanity. If Human species has been able to develop, it is also because nature has equipped it with an effective protection system against bacterial and viral attacks.

Numerous pathogens are airborne in aerosols. They enter the body through the upper airways (nose, mouth). The nose has an effective arsenal to filter microbes by trapping them in the mucus and eliminating them thanks to the nitric oxide (NO) produced in the paranasal sinuses. Oral breathing does not filter inhaled air.

When exhaling, a significant part of the aerosols produced in the lungs is condensed in the nose, which can thus recycle exhaled water and heat, and destroy the pathogens they contain. Mouth exhalation does not offer this benefit.

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Nasal NO is an essential element for the proper functioning of the cardiovascular system, the very one that is attacked by Sars-Cov2.

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We hypothesize that restoring exclusive nasal breathing builds an additional barrier to reduce the risk of SARS-CoV2 infections or their severity. This would then be a complementary means in the public health strategy to fight against Covid-19 and a return to our economic, social, and emotional activities at lower risk.