The novel coronavirus is invisible to the eye because it is microscopic measuring 80-160 nanometers in size; a nanometer is one billionth of a meter.
While we cannot see it in the air or on a surface, millions of us have seen the virus in full color when we discuss it on the local and national TV news, in articles and stories online, and in print media. This is because the virus is routinely pictured and used to attract us to the information being presented. The paradox is that millions of people can now recognize this invisible enemy.
Repeatedly presenting this image is a good idea. When we have a prototype design in mind, we more readily believe and act as if it is physically present. This means that we are more likely to believe and act in ways that can prevent, contain and protect ourselves and others.
Starr, Larry M. and Mody, Darshi, "Our Invisible Enemy" (2020). School of Continuing and Professional Studies Coronavirus Papers. Paper 4.