(2021-07-15) Zvi M Covid 7/15 Rates Of Change

Zvi Mowshowitz: Covid-19 7/15: Rates of Change. Cases rose by over 60% in America this week, and we’re seeing large jumps in cases around the world. I am highly suspicious about the jump in the rate of increase, but Delta variant certainly seems to be the real deal, and this was well above my expectations.

the bulk of this post is a numbers analysis trying to figure out what we know about Delta’s transmissibility and the effectiveness of vaccines in reducing that transmissibility, using data from a variety of sources. Others are encouraged to continue this analysis and try to get to the bottom of this.

The Numbers

Vaccinations

If America’s Delta problem gets sufficiently worse that they start bringing restrictions back, and they don’t start requiring proof of vaccination in such situations but instead once again halt life for the rest of us, I call upon all of us to find this completely unacceptable, the same way I find permanent child masking unacceptable.

In such a scenario, there are two sane choices. You can either let people do what they want, or severely restrict what the unvaccinated can do

Delta Variant

Israel offers the scariest data point, suggesting greatly reduced vaccine effectiveness.

the data supporting the increased deadliness is not that solidly grounded. The extra viral loads are suggestive, and the early data does look like it’s more deadly for a given unvaccinated person, but our data remains not great.

None of this matches the greatly reduced effectiveness hypothesis, unless you presume that behaviors are substantially adjusting during this period, but the shape of the curve isn’t suggestive of that either.

Thus I don’t believe the chart above is a representative sample – the math doesn’t add up.

Our lower bound should presumably be that Delta is 50% more infectious than Alpha, but that vaccine effectiveness is mostly unchanged.

Under Israeli conditions, it seems mostly safe to say that Delta is at most twice as infectious as Alpha, but that about twice is possible. This is the scariest data set.

Under American conditions, it seems mostly safe to say that Delta is going to be less than twice as infectious

above 75% or so

For the USA, a 75% increase in transmission would imply 76% vaccine effectiveness versus transmission.

If things were instead at our lower bound, by assumption, vaccines would remain at 96% effective.

In Other News

Moderna begins a trial for yearly mRNA shot that would combine vaccines for flu, COVID-19, respiratory viruses RSV and HMPV. It turns out that not only does mRNA allow us to cure a wide variety of diseases, it lets us cure all of them at the same time, because the technology allows the payloads to be delivered together