What we can learn from Bay Area vaccine data

Skepticism warranted

Thanks for joining me for the 30th issue of the Golden Stats Warrior, a newsletter for data-based insights about the Bay Area. If this is your first time reading, welcome! You can sign up here. Thank you for your support!


Several weeks ago, I decided this newsletter would be about what we could learn about the Bay Area’s Covid-19 vaccination progress. It’s perhaps the most important issue facing the region (and the world), so an obvious subject choice. But in the course of my research, I’ve realized gaining any insight from this data is an incredibly fraught exercise. When it comes to data comparing how counties or states are doing on vaccine efficiency or equity, you should take it with more than a grain of salt.

Let me share a few examples.

The first question I had about vaccinations in the Bay Area was how the region’s counties compare to one another in vaccination rates. The chart below shows the number of vaccines administered per person as of February 15th for each of the region’s nine counties according to data from the California Department of Public Health and San Francisco Chronicle. (Remember, this data includes both first and second doses. Currently, comparable data on the number of first and second doses administered by county is not available.)

A quick look at that chart would suggest that Napa County has been better able to vaccinate its citizens than other counties in the region. It might also make you think that whiter, lower poverty counties like Napa, Marin, and Sonoma are performing better than their peers.

In reality, the main factor leading Napa and Marin to such high vaccination rates is the age of their citizens. The state distributes vaccines to counties based on the number of eligible residents, which at this point mostly includes people over 65 and healthcare workers. Below is a scatter plot showing the strong relationship between vaccination rates and the share of people over 65 in a county.

Why some counties, like Napa, are administering more vaccines than others with a similar share of seniors, like Sonoma, is hard to say. It may be because there are more healthcare workers (I haven’t found a good explanation—if a reader has thoughts, I would love to hear them).

To better judge the performances of counties, it would be ideal to see the share of vaccine doses released to a county that have been administered. Unfortunately, as far I can tell, it’s not possible to access that data.

Another big question about vaccines is whether they are being distributed equitably. Are people of certain races more likely to get the vaccine? How about people of higher incomes?

Again, unfortunately, it’s difficult to glean insights from data on race and vaccinations. Across the US, demographic data for vaccine recipients have not been carefully collected. It seems that healthcare workers and recipients are not filling out race and ethnicity forms accurately.

We can see this in California’s data. For about 9% of all vaccinations in California, there is no race data at all. Also, the share of people in the data listed as “other” (12.1%) and multi-race (13.9%) is higher than plausible given California’s overall demographics. Data for Bay Area counties have the same issue.

Given the messiness of this data, it seems to be inappropriate to use it for any sort of analysis. And even if the data was more accurate, when examining possible inequities, it’s important to consider how many people of each group are eligible for the vaccine. For example, the Latinx population in California is, on average, much younger than the state’s Black population, so fewer Latinx people will be eligible.

Still, there is some data available that point to inequities. A few Bay Area counties provide data on the number of people in particular cities that received the vaccine. For example, Contra Costa lists the number of first and second doses received for each of the 31 cities in the county. The data show that richer, whiter cities like Danville and San Ramon have had more first doses administered than people over 65, while poorer cities with more Black residents like Richmond and Antioch have had fewer. Some of these differences could be explained by the number of healthcare workers, but a large portion is likely the result of access issues.

Overall, my recommendation is when it comes to thinking about vaccine success, at this point, don’t take raw numbers at face value. Access and fairness when it comes to the vaccine is an incredibly important issue, but given the state of the data, we need to be careful about using it to come to any conclusions.

Just because we don’t have great data, that doesn’t mean we should just assume the vaccine distribution is being done fairly or efficiently. History suggests the rich will receive better healthcare, so it makes sense to monitor access to the vaccine. But in this case, we need to go beyond the headline numbers and pay attention to health researchers and on-the-ground reporting.


Bay Area media recommendations of the week

Two recommendations this week.

First, everyone should read the San Francisco Chronicle’s excellent reporting on the police killing in Danville in 2018. Investigative reporter Rachel Swan acquired videos and documents that suggest the death of Laudemer Arboleda could have easily been avoided. The police officer who killed Arboleda has faced no charges and his department’s internal affairs division found he did not violate any policies.

Second, my friend Tim Fernholz recently pointed me to science reporter Andrew Alden’s Oakland Geology blog. I am sure every post is interesting for the geology buff, but for me, the real fun was in Alden’s attempt to retrace the path of the first European expedition to Oakland in 1770. It’s fascinating to imagine Spanish army captain Pedro Fages and his soldiers walking along the borders of what is now Lake Merritt.

(Seen any great Bay Area media recently? Send it to me!)

Dan’s favorite things

The Bay Area is blessed with steps. Many neighborhoods in our hilly region have stairways to make going up easier for pedestrians. In the East Bay, where I live, those steps were mostly built in the early 20th Century to make it more efficient for people living in the hills to get to the streetcars which would take them to downtown Oakland and San Francisco for work.

Seeking out these steps makes for an excellent urban hike. For a great set of “trails”, I suggest picking up Charles Fleming’s Secret Stairs: East Bay. The book has 38 recommended walks. I’ve done three of them and they were all full of surprise and charm.


If you think a friend might enjoy this newsletter, please forward it along. You can follow me on Twitter at @dkopf or email me at dan.kopf@gmail.com. The Golden Stats Warrior logo was made by the great Jared Joiner, the best friend a newsletter writer could have. Follow him @jnjoiner. Also, thanks to my favorite crow enthusiast Kanchan Gautam for copy editing this week.