Epistemological status: extremely uncertain. I’m not an epidemiologist and am writing down these thoughts to force myself to think through what I actually think and to memorialize what my thoughts were as of July 27.
There are a few things that I believe that are a little bit outside of the current mainstream thought with respect to the COVID-19 crisis. Nothing I’m going to write here is really novel, in that my thoughts have been shaped pretty dramatically by the research and commentary I’ve read from a variety of different experts. However, it seems a lot of these beliefs haven’t penetrated mainstream media commentary yet, and definitely not in the conversations I have with my friends so I wanted to sit down and lay out where I’m at with this crisis.
“Herd immunity” has a meaningful effect at substantially <60% of the population
The 60% number was originally bandied about (often with a range of 60% – 80%) when we first started talking about potential responses to the crisis. However, upon closer reading, it turns out that that number is based on a mathematical model that makes some pretty unbelievable assumptions (IMQHO). In particular, that 60% number assumes that the population is totally homogenous in terms of behavior and disease susceptibility — this is something we know isn’t true (and should be obvious!). My belief is that the people most likely to catch and spread the disease (e.g., folks who take the subway to work and work in jobs with a high degree of exposure to others on the job) are the people who catch the disease first. Since they are also the largest source of spread, once they have immunity then we’ve shut off the main disease-spreading vector and start to realize the benefits of “herd immunity” already. I believe that New York City is currently benefiting from the effects of herd immunity and the lack of a surge following the BLM protests in late May / Early June are a strong proof point.
Since “herd immunity” falls on a spectrum and is very difficult to measure even retrospectively, I have a hard time figuring out what a good “prediction” is to make around this belief but I do believe that the estimates of 60%-80% aren’t right and that to some extent1though definitely not entirely! we will look back on the Sweden strategy as being not-entirely misguided.
Mask usage is extremely effective for preventing the spread of COVID-19
I think widespread mask usage and avoiding indoor dining are probably the two biggest things we can do as a society to slow the spread of COVID-19. Trump’s delay in promoting mask-wearing2and he still isn’t doing enough to promote mask-wearing! cost thousands of lives and we will look back on that as probably the single-worst policy mistake he made during this crisis. That mask-wearing is so cheap and so easy and that the government failed to promote it sufficiently is a real travesty. I think that with 90% adherence to mask wearing and without indoor dining / indoor bars the virus will basically stop spreading.
I expect that mask-wearing will continue until we have a vaccine and that mask-wearing will become generally more accepted in Western culture.
Indoor dining is a bigger problem. Eating in a closed restaurant or, even worse, a bar, is really the perfect vector for spreading aerosolized respiratory illnesses. It’s hard for me to see a world where we believe it’s safe to open up bars for anything that looked like pre-COVID use until we’re confident of widespread immunity. I really wish NYC would start to open restaurants for indoor dining just so we could see what the impact is on the rate of spread — given my belief about herd immunity above I think that NYC is probably the safest place in the country to start opening restaurants, and it’d be good to know (from a policy perspective) just how dangerous it is.
Predictions + my subjective confidence:
- We have a vaccine approved for use in the USA by December 31, 2020: 40%
- We have a vaccine approved for use in the USA by June 31, 2020: 90%
- The incidence fatality rate of COVID-19 is less than 0.5% (5 out of 1000 people infected): 80%
- We reach a consensus that Vietnam / Thailand / Laos / parts of China had pre-existing immunity due to exposure to earlier coronaviruses: 80%
- % of the population of NYC with innate resistance to COVID-19 (no infection, no antibodies) over 10%: 75%
- More than 1% of people can get COVID-19 twice: 10%