A lot of important numbers are included in it, many of which are somewhat obscured by either medical jargon (the slide show was not created for public consumption) or unclear presentation. So I’ve taken a stab at breaking out some of the more interesting data and presenting it a bit more cleanly.
For example, the slides begin by comparing the rates at which infections, hospitalizations and deaths occur among the vaccinated and unvaccinated populations. There’s no real comparison; the incidences of all three of those outcomes is far higher among the unvaccinated than the vaccinated populations.
But it’s worth picking out the relative frequencies of incidence in particular. The rate of infection among the unvaccinated, for example, is eight times as high as the rate for the vaccinated. When it comes to hospitalization, the divergence is even wider: The unvaccinated are hospitalized at 25 times the rate of the vaccinated.
Notice that the data are through July 24 — meaning they include data for the delta variant that is now the most common version of the virus in the United States.
The document also notes that, as of that date, there were about 35,000 symptomatic infections per week among the 162 million vaccinated Americans. That’s different than the number of infections overall; it could be the case, for example, that a large percentage of infections among the vaccinated are asymptomatic. But if we compare that 35,000 figure to the total number of infections in the week ending July 24 — more than 351,000 — we see that new infections are much more common among the unvaccinated than the vaccinated as a function of population. (Here we’re assuming a total U.S. population of 331 million.)
A key graph from the piece is actually layered on top of a New York Times chart from February 2020. It compares the fatality rate of different diseases (the vertical axis) to the rate of transmission (the horizontal). A dot that is in the upper left corner is very deadly but not very transmissible; a dot at lower rate is very contagious but not very deadly. (I’ll note that some of the positions of the dots vary from some estimates of transmissibility and fatality.)
What you want to pay attention to are the pink and blue boxes. Those are the estimated ranges of fatality and transmissibility for the original virus (elsewhere called the alpha strain) and the new delta variant, which is the blue box. That the blue box is farther to the right but not much higher means that the delta variant is believed to be much more contagious (as contagious as chickenpox, potentially, as the slide notes) but not much deadlier. Not great, but could be worse. (Another slide documents evidence from other countries showing slightly higher odds of hospitalization and death with the delta variant.)
The document also shows evidence from three countries — Scotland, Canada and Israel — evaluating how effective the Pfizer-BioNTech vaccine is against the two strains of the virus after a person is fully vaccinated. In the Scottish study, published in the Lancet journal in June, the vaccine is less effective at preventing infection with the delta variant, although it’s still very effective. It is just as strong in preventing death.
The data from Israel are less positive, showing significant declines in the effectiveness of the vaccine, although it remains at least 64 percent effective in preventing both infection and hospitalization. There has been a great deal of debate over that particular piece of the data.
One bit of good news is that there is little evidence that the effectiveness of the vaccine wanes over time, although, as pointed out by Robert Wachter, chairman of the Department of Medicine at University of California at San Francisco, there is evidence that natural immunity — immunity from a prior infection — wanes after six months.
Another chart shows how vaccinated individuals have made up increasing percentages of those being hospitalized and those who die of the virus. This, it notes, is largely a function of more people being vaccinated and of the most at-risk populations being overwhelmingly vaccinated. When compared to the percentage of adults who are vaccinated overall, the percentage of vaccinated individuals among those hospitalized or who’ve died remains disproportionately low.
The document is largely centered on sharing information about the pandemic, and recommendations based on the data are more subtle. But on one slide, evaluating the utility of non-pharmaceutical interventions — such as wearing masks, for example — the CDC went out of its way to introduce a big, bold recommendation across the data.
“Given higher transmissibility and current vaccine coverage,” it reads, “universal masking is essential to reduce transmission of the Delta variant.”
The war has changed.