How much more dangerous is Delta? An incomplete peek

No formal studies yet because widespread Delta is still quite new in the US healthcare system, though some preliminary papers are starting to appear out of the UK which has been wrestling with this for 4–6 weeks longer. So far, younger people (< 50) appear twice as likely to go to the hospital and 3 times more likely to die if they do go. The data are too sparse on older unvaccinated folks.

The impression I have is Delta is more dangerous, which makes sense. If viral loads in noses are 1000 times higher than the original wild type COVID, it stands to reason there will be more virus through the body, and the impact on the body will be higher. It is still early in the US experience with Delta, so we won’t know for sure for a while, but there is some information.

Before we go further, note: this Medium article discusses the mortality rates of people who ended up in the hospital. These are people who were sick enough to have to go the hosptial and most people who contract COVID do not. These numbers do not reflect the odds of dying from a COVID infection overall, but perhaps do reflect something close to the odds if you get sick enough that you have trouble breathing.

Last Year, pre-Delta

The plot below from the paper communicates many things. Younger people do better, and as the medical community learned new things about treating people, mortality rates dropped. Also note that this is also before B.1.17 (Alpha [see endnote]) was common in the US. So if there was any change from Alpha, that is not shown here. (As a note, I have heard, but not read papers about it, that the UK saw some evidence that it was somewhat more lethal.)

From “Mortality Among US Patients Hospitalized With SARS-CoV-2 Infection in 2020” published in JAMA infections diseases on April 8th 2021. Notice the falloff in mortality amongst hospitalized patiens by mid 2020 as doctors learned about various therapies. Also note how low mortality was for folks under 50.

So what is going on now with Delta?

Other than that, I don’t have much to look at apart from anecdotes from doctors on the ground in large ICUs about how now, compares to then, mostly from different news stories.

I have heard that people are not lasting as long when they end up ventilated. I remember seeing a plot in a paper many months ago where the median time on a ventilator in mortal cases was around 6 weeks(!) . Now, people are dying within 2 weeks (and they are younger so should tolerate it better…)

This morning I listened to an interview of a hospital administrator at Mercy Hospital in SW Missouri where Delta has been dominant for longer than in much of the US. A lot more COVID patients in the Mercy ICU are younger, “in the their 20s and 30s and 40s.” I suspect this is because older folks are more likely to vaccinated, and even when they are not, they don’t go out into the world as boldly or as often and the younger folks. That is mostly the under 50 crowd. Looking at the figure from the JAMA paper, this is the group with a mortality rate 5% amongst hospitalized patients last year.

Turns out, since July 1st, 17% of Mercy’s ICU patients have died. The number is 78 which is starting to be large enough to be statistically meaningful . They are dying at more than 3 times the rate the same people would have died last year. I have been hearing similar stories in recent weeks, but this was the first that put down some statistics that felt believable. So far, it appears twice as likely Delta infectees will go to the hospital. If you multiply those together a younger person is 6 times more likely to die if infected by Delta vs. Alpha.

Once the data is in and there are studies, I believe we will find Delta is a lot more angerous. We already know it is a lot more contagious. It is as contagious as chicken pox ….except unlike chicken pox you don’t have a childhood immunity and there are hundreds to thousands of contagious people in your community. If you do not hide in your home you will catch this one at some point. So get vaccinated. If you are older you are at serious risk of death if you don’t. If you are younger, the danger is much increased over what it was last year. Hundreds of millions of people have had these shots in their arms for several months and some 10s of thousands for over a year. That is a pretty good baseline of data. Vaccination is definitely safer than the illness, and Delta is so contagious, you will contract it at some point. So get the shot.

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Endnote on Variant of Concern (VOC) designations by the World Health Organization (WHO):

Alpha was the VOC first identified in the UK late last year. It is the first VOC the World Health Organization named, so it was called Alpha. Earlier variants/original strain that are not VOCs are generally just referred to as ‘wild type’.

This Chicago Tribune story lists the first 4 VOCs and provides a brief explanation.

The World Health Organization’s page on tracking variants has a nomenclature description partway down.

I have a background in science. I back up nearly everything science I write with peer reviewed research, or at least preprints and pointers to my data sources