Breathing Is Enough: For the Spread of Influenza Virus and SARS-CoV-2 by Breathing Only

<b><i>Background:</i></b> The transmission of respiratory viruses such as influenza and corona viruses from one person to another is still not fully understood. <b><i>Methods:</i></b> A literature search showed that there is a strong scientific rationale and evidence that viruses are very efficiently spread through aerosols by the patient's breathing only. It is not necessary for the patient to cough or sneeze. <b><i>Results:</i></b> The exhaled aerosol particles are generated by normal breathing in the deep lung through reopening of collapsed small airways during inspiration. These mucus/surfactant aerosols (size range between 0.2 and 0.6 μm) can transport viruses out of the lungs of patients and be present in the room air for hours. <b><i>Conclusion:</i></b> These aerosol particles are difficult to filter out of the air; because of their physical properties, new strategies must be developed to protect people from these virus aerosols.