More data became available this past week, and I think it is safe to say the delta variant is different enough that we will need to modify pandemic practices as the CDC has begun to do.
[Also, on a lighter note, I decided to investigate where the idiom in my title originated. As best I can tell, the first appearance in print was the March 13, 1971 issue of The New Yorker (page 30) in an unattributed posting in the "Talk of the Town" section commenting on what would happen if China entered the Vietnam War. The term appeared in quotation marks and I suspect that was a nod to the fact that the term was already in use.]
Delta Data
The CDC annoyed me early in the week when they came out with new recommendations for masking and other practices, referencing internal/unpublished data but not providing it. Subsequently the Washington Post released a draft slide set from the CDC that I read but was not going to comment on that because it was clearly a draft document. You can look at it but your time is better served by going to the CDC/IDSA COVID-19 Clinician Calls site where CDC's Dr. Tom Brooks provided an overview on Saturday July 31 (presentation not yet posted as of August 1).
Here's the bottom line on what's new and serious about the delta variant. A multisite outbreak on July 4 in Barnstable County, MA is showing us that not only is the delta variant highly contagious but also that vaccinated individuals had similar cycle threshold values to unvaccinated people. Cycle thresholds are sort of a biomarker for amount of virus in nasal secretions, though it is clearly not as reliable as, for example, viral load in blood in HIV patients. Cycle threshold also does not provide any exact translation into amount of viable intact virus present. Still, the concern is that even vaccinated individuals have significant amounts of replicating virus that they can pass on to other individuals and also are themselves a source of new variants. Another, non-peer reviewed, study suggests that the period of contagion with delta may be longer than with the original strain or earlier variants, though less so for vaccinated people. This could mean that quarantine periods after delta infection will need to be extended beyond our current guidelines. We need follow-up studies, but this early information is very sobering.
Note that we continue to see new, encouraging data that vaccination is still incredibly effective against infection (though slightly less so for delta variant) and for protection against hospitalizations and death. The mRNA vaccines are still working far better than anyone hoped to predict a year ago. (We don't yet have enough information about Janssen/Johnson & Johnson vaccine with delta, it hasn't been authorized as long so not as many people in the US have received it.)
Pandemic Communication
My whining about CDC being less than transparent and straightforward this week leads me to mention that CDC (and also WHO) has had a panoply of pandemic playbooks available well before the current pandemic, with a lot of updating following our 2009 influenza A pandemic (remember that?). I decided to browse the CDC's 2014 Crisis and Emergency Risk Communication Manual. At 462 pages it is not for the faint of heart, but it was interesting to reflect on communication with the current pandemic. In my nonexpert opinion, I would say that early in the pandemic it seems as if no one had even consulted this manual. Lately things are better, but the CDC needs to provide timely, clear updates and provide the supporting data at the same time so that the rest of us can make our own assessments. This is a tough job, no doubt, but I'm hoping they are learning quickly how best to manage public information in these very difficult times.