Some of this I agree with and some of it I don’t. They don’t talk about how structural racism affects Covid deaths enough.
“In a recent interview, Linda Villarosa outlines the three major causes that she and other public health researchers have identified as causes for the huge racial gap in Covid mortality:
1) Proximity to the virus:
Black people live and work in environments where the virus is difficult to escape. They are more likely to work in essential services where it is difficult to engage in social distancing, and they are more likely to live in inter-generational homes in densely populated areas. All of this leads to more contact with the virus; more contact leads to more infection, and more infection leads to more death.
2) Racial bias in healthcare:
Black people receive worse healthcare than white people. Black patients are less likely to be believed by physicians, essential interventions are more likely to be delayed, and resources tend to be allocated to white patients. Naturally, if you get worse healthcare because of your skin colour, your outcomes are going to be worse.
3) Pre-existing conditions:
For a variety of reasons, Black Americans have higher rates of conditions that make Covid-19 more dangerous. Rates of diabetes, hypertension, and asthma are all higher in Black communities, which leads to higher Covid-19 mortality.
4) The vitamin D model
I’ve been very interested in vitamin D deficiency as a potential cause of Covid-19 mortality because it’s one of the best treatment candidates for widespread use. Unlike other potential therapies, we already have a lot of vitamin D clinical research data and we know that it’s safe to consume prophylactically. Vitamin D would also go a long way to explain why people of colour are dying at such high rates in the northern hemisphere where sunlight is currently scarce, but not in equatorial or southern parts of the world where sunlight is currently abundant. While skin colour is not the only factor that changes serum vitamin D, and race is a social category that’s only loosely related to skin colour, it is the case that in most northern latitudes people with darker skin (tend to have lower vitamin D)[https://nutrition.bmj.com/content/early/2020/05/20/bmjnph-2020-000096#ref-13] levels in the winter.
A recent study provides a strong argument that the missing factor is vitamin D. The study uses a technique called mendelian randomisation, which requires a bit of explanation: In the ideal world, we would answer the question of whether vitamin D deficiency increases your risk of dying of Covid-19 by controlling for vitamin D in the model, but we don’t have information about everyone’s vitamin D levels. Mendelian randomization is the idea that if you have information about something that you know is related to the thing you wish you had data on, then you can include that as a proxy. In this case we know that people with darker skin tend to have lower vitamin D levels than people with lighter skin, and that that probably gets worse as you move north. The intuition here is that the skin’s ability to synthesize vitamin D is less important in Florida than Wisconsin because intense UVB radiation is abundant for most of the year. So this study uses race + latitude as a proxy for vitamin D levels.
The rules of mendelian randomization are that the randomizing factor can’t be directly associated with the outcome, and it can’t be associated with other explanatory factors.
To reiterate, this argument is not to dispute the factors that Villarosa proposes. None of the papers about vitamin D and Covid challenge the idea that healthcare bias, pre-existing conditions, and proximity to the virus are major causes of excess mortality, and in fact all of the data supports that conclusion. What this does challenge is the idea that that’s the whole story. It seems like excess Covid mortality among people with darker skin is not completely explained by socioeconomics, location, or pre-existing medical condition. And if that’s true, it’s good news because it means that there may be something we can do about it. Vitamin D is a good candidate for that missing piece because it helps to explain why latitude would increase the racial gap in Covid mortality.