Question: I was just reading in Politico that the president of the American Federation of Teachers is warning that teacher strikes may be coming to protest unsafe working conditions if schools reopen in states where infections are surging. According to the article, “The union, which represents 1.7 million educators in the United States, adopted a resolution this month that says schools should only open in places where the average daily community infection rate among those tested for the coronavirus is below 5 percent and the transmission rate is below 1 percent.” Which states meet this criteria and where can I find these state-by-state data?
Answer: These criteria are written slightly differently than I usually see them. Put another way, the first indicator, “average daily community infection rate among those tested for the coronavirus is below 5 percent,” is “average test positivity rate <5%” and here I would expect the average to be the 7-day rolling average. We can get these data directly from covidtracking.com or we can use this data visualization tool from Johns Hopkins, which pulls data from covidtracking.com. When it comes to the second indicator, “transmission rate is below 1 percent,” this is the reproduction rate — R0 — and it is a measure of the average number of people an infectious person infects. Anything above 1 (not 1% as stated in Politico) is an indication that the virus spread is growing rather than contracting. R0 is a relatively simple concept, but it is challenging to measure and requires mathematical modeling, as described by this 2019 paper from Emerging Infectious Disease. RT.live (a “public service” site run by the cofounders of Instagram) uses case count and test positivity rate data from covidtracking.com to model R0 by state (Figure 1). For ease of reference, I made a table that shows which states meet the test positivity rate and R0 criteria (Table 1).As of July 29, only 6 states meet the American Federation of Teachers’ criteria for reopening — Delaware, Maine, Michigan, New York, Ohio, and Vermont.
Figure 1. Reproduction Rate by State (from RT.Live)
Table 1. Reopening by State
