The current best estimate is an assumption.

The CDC issued an updated Covid 19 Pandemic Planning Scenarios. They have come out with several interesting estimates but probably the most important is that they estimate that 40% of infections, meaning positive tests (new cases) are asymptomatic. Asymptomatic as opposed to pre-symptomatic means that the person has not and will not suffer physically from the covid-19 virus.

If correct this means that whenever you hear a number of new cases, total cases, etc. 40% are not now nor ever will be ill. It would mean, for example, that 40% of the 3.75 million plus cumulative cases or over 1.5 million people never even suffer(ed) from the virus. In fact, if we were not testing in such unprecedented numbers, they would not even know they had the virus.

Some immunologist believe that many of those that test positive are actually not asymptomatic at all, rather they are people who are immune to the virus. They believe that the positive test is of people whose immunity system has smashed the virus and the sensitivity of the test picks up the fragments of the virus that they have not yet shed. These fragment are not contagious. This is speculation though it is based on more science than the 40% figure given by the CDC. Here is the CDC footnote on that figure.

The percent of cases that are asymptomatic, i.e. never experience symptoms, remains uncertain. Longitudinal testing of individuals over time is required to accurately indicate the absence of symptoms for the full period of infectiousness. Current peer-reviewed and preprint studies vary widely in follow-up times for re-testing, or do not include re-testing of cases. Additionally, studies vary in the definition of a symptomatic case, which makes it difficult to make direct comparisons between estimates. Furthermore, the percent of cases that are asymptomatic may vary by age and studies also vary in the age groups included. 

If you think that is a vary "scientific" way of saying "we don't know" you are correct. But that little bit of footnote jujitsu is nothing compared to the one describing how infectious asymptomatic "cases" are. Those sick people that never get sick but infect others because they don't wear mask cases. Here is how the CDC describes their "knowledge" behind these "silent spreaders." I guess they are silent because they neither cough nor sneeze. 

CDC footnote on asymptomatic infectiousness.

The relative infectiousness of asymptomatic cases to symptomatic cases remains highly uncertain as asymptomatic cases are difficult to identify and transmission is difficult to observe and quantify. The estimates for relative infectiousness are assumptions based on studies of viral shedding dynamics....

They then go on to list the various studies that are inconclusive as to the infectiousness of these non-sick, sick cases of Covid 19 and conclude with this final statement. 

The current best estimate is an assumption.

Excuse me? This if you remember, the asymptomatic infectiousness, is the reason given to reverse course on mask wearing. Nice to know that we are following the science.

So I know you are dying to know what that assumption is. Well here it is folks this is the CDC Pandemic Planning Scenario assumption of this nation dividing "suggestion." 

 "Infectiousness of asymptomatic individuals relative to symptomatic"

(drum roll)

75%

After admitting to not having a clue, the CDC assumes that an asymptomatic person is 75% as likely to infect another person as someone who actually shows symptoms, you know like sneezes or coughs. 

There is no proof, there are no studies that reach this conclusion, it is merely an assumption. The IHME has used this assumption to "model" 33,000 less deaths if we all would just wear masks. I'll tell you a little secret, if there turns out to be less deaths than their projections, they will credit it on mask usage, if there are not less deaths, they will blame it on less than full compliance. Today there was a study (based on modeling) saying we could have saved forty thousand live if we had only used masks from the beginning, stupid Trump. I know that in the "beginning" the CDC, Fauci, the Surgeon General and anyone in our national Health Care elite class within six feet of a microphone told everyone to not wear a mask but hey that was then, geez what boobs you are. Now though peasant, you are unpatriotic if you do not wear a mask according to our assumption. And the assumption is built on the guess that 40% of "cases" are asymptomatic to begin with, but that could vary depending on what day of the week it is. 

I thought the first rule of medicine was "first do no harm." The CDC must not realize that its one and only patient is the United States of America.