I superficially looked at the CDC site, and learned 2 things about delta:
1. CDC says the Delta Variant is one and a half times as contagious as Alpha (which I understand is the first new iteration after original Covid-19. What they mean is that if a person infected with Alpha would (under a particular set of circumstances) infect 2 additional persons; then a person infected with Delta, under the same set of circumstances, would infect 3 people. (Of course a major epidemic management goal would be to get the that number down to .9 or less.).
A transmission rate of 3 rather than 2 is huge, played out over even a short time makes a big difference. ALPHA 2 x 2 x 2 x 2 x 2 = 32 patients after 5 transmission. DELTA 3 x 3 x 3 x 3 x 3 = 243 patients after 5 transmission.
The CDC is hedgy about whether or not catching Delta causes worse cases or not, but they imply that it is. (Elsewhere, on legitimate sites, I have seen that the death rate for Delta is 1/19th that for Alpha. There may be a statistical artifact unduly increasing the death rate gap between the 2 variants, but not anywhere near enough to explain such an extreme ratio as 1:19.)
The CDC places each variant in one of the three following categories:
1. Variant of Interest (VOI)– View current VOI in the United States that are being monitored and characterized
2. Variant of Concern (VOC)– View current VOC in the United States that are being closely monitored and characterized by federal agencies
3. Variant of High Consequence (VOHC) – Currently there are no SARS-CoV-2 variants that rise to the level of high consequence
Delta is categories as a Variant of Concern, which is defined as follows;
Variant of Concern
A variant for which there is evidence of an increase in transmissibility, more severe disease (e.g., increased hospitalizations or deaths), significant reduction in neutralization by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures.
The site has additional details about this as well as the other 2 categories.
Confusion about Delta is partly because not enough is known about it yet to give definitive answer; part is because of poor logic checking, fact checking, and accurate reporting by the 4th Estate; and part is untrustworthy history by official, government and medical sources who at times have transparently curated their communication in order to steer mass behavior for the greater good, even when they fudge facts under the banner of: “The Science.”