During his August 27 press briefing, Health Officer Dr. Jeff Duchin provided context around “breakthrough cases” and how risk changes for vaccinated people compared to unvaccinated people.
As shown in the graph above, 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. This is an increase of 70 new cases per day per 100,000 people.
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.
Among not-fully-vaccinated people, age-adjusted hospitalizations increased from 1/100,000 people per day to 7/100,000 people per day. During this same time period, people who were fully vaccinated saw an increase from 0.04/100,000 people per day to 0.2/100,000 people per day.
The bottom line here is clearly that COVID-19 vaccines – which are primarily intended to prevent serious infections, hospitalizations and deaths – are working. These vaccines reduce the risk that a vaccinated person will catch and transmit COVID-19 and provide tremendous protection against severe infections, hospitalizations and death. But you need to get vaccinated for them to work.
Health Officer dr. Jeff duchin
Originally published August 31, 2021.