- A few quick links re: COVID-19/Delta
By Holden Karnofsky 3 min read

A few quick links re: COVID-19/Delta

There is a lot of confusing and/or misleading information out there about the recent Delta-driven COVID-19 surges.1 Here are some of the links I've found most helpful for getting a handle on the current situation: how risky things are at the moment and how much vaccines are helping. I've prioritized links that are pretty simple and digestible but (IMO) credible. (This isn't a post about all the ways the COVID-19 policy response could be better. I generally recommend Marginal Revolution for that.)

microCOVID Project:2 synthesizes lots of research about the transmission risks and provides a calculator for how risky specific activities are. I highly recommend this site on the whole, especially if you are trying to reach consensus with other people on which activities are too risky, but also if you just want to get some quantitative information on COVID-19 risks that was created via scrupulous literature review instead of via a quest for clicky headlines. Its update on the Delta variant implies that Delta is about 1.5x as contagious per hour of exposure; that vaccines are less effective but still very effective against it (83% risk reduction vs. 90% for Pfizer/Moderna, consistent with Youyang Gu's rough estimate). It also discusses the sources it used to arrive at this conclusion.

July 13 overview from Tomas Pueyo, whom I've generally found to be one of the most careful+clear writers on this topic. I didn't find his more recent update to add a ton to that, but I'm very much looking forward to his upcoming analysis of "long COVID." He seems to be estimating something like 50% protection against infection and 90% protection against hospitalization, from most vaccines (partially offset by Delta being ~2x more infectious). provides something that has been really undersupplied IMO: estimates of true (not just reported) COVID-19 prevalence, up to date, by granular geographic area. A very hacky way to estimate your risk is to assume that in a given area, if you are taking the average level of precautions, you'll have the same odds as the average person of contracting COVID-19, which means you can simply look at "new cases per 100k people" and divide by 100k to get your daily probability of infection. This is especially useful for deciding where to travel. I haven't vetted the methodology for, but it is recommended by Youyang Gu (his other recommendation is not up to date, not as geographically granular, and only estimates total cases, not cases per 100k population, making it harder to use).

Nice simple presentation of lots of charts on deaths and vaccinations from Jeff Kaufman.

Finally, my favorite links for cutting COVID-19 risk for you and those around you: rapid tests. Worth checking both Amazon and Wal-Mart as availability varies a lot; here's BinaxNOW at Wal-Mart, BinaxNOW at Amazon, QuickVue at Wal-Mart, QuickVue at Amazon. Aside from getting vaccinated, rapid testing seems like by far the least life-disrupting way to cut your risk.

Twitter Facebook Reddit More



  1. This article is an example of reporting lots of statistics like "Israeli health officials have said 60% of current hospitalized COVID-19 cases are in vaccinated people" without addressing things like what percentage of all people are vaccinated in the relevant areas, possible sources of reporting bias, etc. 

  2. Disclosure: Catherine Olsson, a former coworker, is one of the collaborators on this project. 

For email filter: florpschmop