Unvaccinated Californians were between 15 and 20 times more likely to die of COVID-19 than vaccinated ones when deaths from the disease most recently peaked at the start of September, according to state data.
The California Department of Public Health publishes data on the vaccination status of people who test positive for coronavirus as well as people who are hospitalized with, and die from, COVID-19. Their data shows that the death rate among unvaccinated Californians aged 16 and older soared in early September, reaching a peak of 13 average daily deaths per million on Sept. 6.
In contrast, the average daily COVID-19 death rate for fully vaccinated Californians peaked at just under one in a million in late August. By Sept. 6, it had declined to 0.75. COVID-19 death rates for both vaccinated and unvaccinated Californians have dropped since September, and are now averaging 0.26 and 5.8 deaths per million per day, respectively.
The gap in deaths between vaccinated and unvaccinated people exists across the U.S. A study published in early September by the Centers for Disease Control and Prevention, which tracked over 600,000 COVID-19 cases in 13 states from April through mid-July, found that unvaccinated people were over 10 times more likely to get hospitalized with the disease and 11 times more likely to die from it.
In the CDC study, unvaccinated people were 5 times more likely than vaccinated ones to test positive for coronavirus. In California as of late September, unvaccinated people were about 7 times more likely to test positive than vaccinated ones.
This data shows that the vaccine is not quite as effective in preventing overall infection by the delta variant as it was against earlier strains; another study published by the CDC in August found that once delta became the dominant coronavirus strain, vaccines went from being 91% effective at preventing infection to 66% effective.
However, it also shows that vaccinated Americans have remained strongly protected from serious disease and death in the latest surge. Through at least the end of August, vaccines remained about 90% effective in preventing COVID-19 hospitalizations, according to the CDC.
CDC data also shows that, as of Oct. 7, states with higher vaccination rates have lower death rates on average than less-vaccinated states.
It’s also likely that these statistics don’t fully capture vaccine efficacy, because vaccinated people are older on average than unvaccinated ones, and thus are more likely in general to get seriously ill from, and die of, COVID-19.
Even for unvaccinated Californians, COVID-19 death rates have dropped off dramatically since early September. The state’s average death rate is currently the lowest of any U.S. state, at just 0.3 daily deaths per 100,000 people according to the CDC. Its weekly case rate is also the lowest of any state, at 66 new cases per 100,000.
California’s current low death rate is likely due to a combination of increasing immunity driven by high earlier case rates, plus strict public health rules and above-average statewide levels of vaccination. As of October 6, 61% of all Californians are fully vaccinated, compared to 56% of Americans overall.