COVID-19 Daily Update, Cases Go Back Up

Last week I wrote about how there have been surprisingly low cases are not climbing again in many locations that had a high first wave of disease. Most of the "second peak" of cases in the US were coming from new locations, which did not see an initial first wave of infections. I discussed why that was surprising, and gave several theories for why this might be happening. 

This week, we need to revisit that, and discuss regions which were hit hard early on, but where cases are, indeed, starting to rise a second time. 

One location like this is New York: 

Daily new cases there appear to be on the rise again, and this does not appear to me to be due to increases in testing. Estimates of Rt in NY yesterday put it at around 1.06, and possibly climbing. On the whole, cases are still falling in the US, with an Rt estimate of 0.96. Before now, New York has consistently had a lower Rt than the rest of the US, but that is no longer the case. 

We can see even more pronounced evidence of a resurgence of cases in other early hit places around the world, including Italy, Germany, and the UK:

Similar charts exist for many other locations in Europe. 

If these patterns continue, they may well undermine the idea that locations that were already hard hit by the virus have sufficient immunity levels to stave off a second wave of infections. Or it may indicate waning levels of immunity in those early hit locations. 

It is going to be important to watch these locations to see what happens next, because that has the future to largely dictate how the next few months go around the world, while we wait for a vaccine.

You will note that these observations may well undermine some of what I wrote last week. We are in a very uncertain time again, with a large number of unknowns, and it will be important to follow the data wherever it leads, and to be willing to change our minds rapidly if necessary (and to be able to admit when we don't know the answers).