1. Very important new paper via @MarkMuro1 on the connection between density & COVID-19.
cep.lse.ac.uk/pubs/download/…
cep.lse.ac.uk/pubs/download/…
2. The paper by an LSE team looks at the outbreak & spread of COVID-19 across 1197 US counties which comprise 82% of US counties.
3. It uses several measures of density, including simple density and population-weighted density, and adds an instrumental variable based on geological conditions.
4. The study finds that density makes big superstar cities more susceptible to early & severe outbreaks. They suggest this has less to do with density per se, and more to do with the greater connectedness of bigger, denser cities.
5. Furthermore, they find "no evidence that population density is positively associated with time-adjusted COVID-19 cases and deaths."
6. But perhaps the big finding is that density actually appears to mitigate the severity of the outbreaks.
7. They write: "we find that population density is positively associated with proxies for social distancing measures, access to healthcare and income, highlighting the importance of these mediating factors in containing the outbreak."
8. They conclude: "First, density is associated
with an early arrival of COVID-19, so that urban cores and superstar cities get a head start on the spread of the disease. Second, the subsequent spread - once COVID-19 has arrived - is not faster or deadlier than in smaller towns."
with an early arrival of COVID-19, so that urban cores and superstar cities get a head start on the spread of the disease. Second, the subsequent spread - once COVID-19 has arrived - is not faster or deadlier than in smaller towns."
9. They add: "Cities get hit first, but do not necessarily get hit harder. "
10. Ultimately, they conclude that "several
mechanisms may explain these findings. Large cities are intensely inter-connected with other locations, which can explain early onset ..."
mechanisms may explain these findings. Large cities are intensely inter-connected with other locations, which can explain early onset ..."
11. "Yet, in the case of within-city spread, many different offsetting forces may be at play."
12. And the kicker: "Crowding may promote the
spread of the disease but differences in precautionary measures, access to health care and demographics may contain it. As a result, it is important to distinguish
differences in spread between and within locations."
spread of the disease but differences in precautionary measures, access to health care and demographics may contain it. As a result, it is important to distinguish
differences in spread between and within locations."
