The same as with the flu, pneumonia, mumps, measles, etc., as COVID is just a Wuhan-weaponized mutation of influenza. Droplets in the air from sneezing/coughing (that enter via nose and mouth) are the major cause. This is not to discount the mass hysteria spread by Fauci, CDC, WHO, and our politicians, through the deluge of propaganda and disinformation from TASS West (MSM), along with the censorship of information by Silicon Valley.