Thread by @DocJeffD

We hear/read a lot about "breakthrough" infections & the % of people getting or hospitalized or dying with CoV-19 that are vaccinated. But this tells us nothing about what is most important: how the risk changes for vaccinated people compared to unvaccinated people.
1/

To determine the risk, you need to know how frequently these outcomes occur in vaccinated & unvaccinated groups (the rates of disease in each group). To compare most accurately, we should compare vaccinated & unvaccinated people of similar ages (adjusting for age).
2/

Age-adjusted CoV-19 rates for past 30 days in King County, WA:
Compared to fully-vaccinated people, those not fully vaccinated are:
- 6 X more likely to test + for CoV-19
- 37 X more likely to be hospitalized for CoV-19
- 67 X more likely to die due to CoV-19 related illness
3/

In the recent Delta surge, the age-adjusted rate of CASES among people who are not fully vaccinated increased from 7 daily cases/100,000 people at the beginning of July to 77 daily cases/100,000 people as of August 17, an increase of 70 new cases per day per 100,000 people.
4/

During this same period, the age-adjusted rate of CASES among fully vaccinated people increased from 1 daily case/100,000 people to 10 daily cases/100,000 people, an increase of 9 new cases per day/100,000 people.
5/

Among not-fully-vaccinated people, age-adjusted HOSPITALIZATIONS increased from 1/100,000 people/day to 7/100,000 people/day vs. an increase from 0.04/100,000/day to 0.2/100,000 people/day for the fully vaccinated.
6/

Bottom line: CoV-19 vaccines are doing a terrific job protecting the vaccinated from CoV-19, especially for hospitalizations and death.

Clarification: denominator is per 100,000 person-days

Clarification: denominator is per 100,000 person-days