February 20, 2021
We’ve come to the end of another work week, so let’s compare where we are versus the prior week in Alabama.
The average of new cases has declined from 1,301 per day for the 5 days ending February 12, to 876 cases per day for the 5 days ending yesterday. However, the 7-day moving average for positivity has risen from 18.9% last week to 20.2% this week, reflecting a significant decline in testing this week. As of February 12, there were 1,140 patients in 97 reporting hospitals, or 11.8 patients per hospital. One week later, there are 895 patients in 99 reporting hospitals, or 9.04 patients per hospital. Over the 5 work days ending on the 12th, there were 719 reported deaths, whereas there were 346 reported deaths for the 5 days ending the 19th.
In short, new daily cases and hospitalizations and deaths all have steadily declined in this week-to-week comparison, but the positivity rate has held steady, even edging up a bit. This actually makes sense. As the more vulnerable among us get vaccinated, you would expect hospitalizations and deaths to decline. While overall cases also have declined amidst great fanfare in local media, the lower case count is at least partly due to fewer tests. The residual high positivity rate suggests that asymptomatic or mildly symptomatic cases may be just as prevalent as before.
So, when can we expect to reach herd immunity? An article in the NY Times attempts to answer that question today, pointing to the roles that vaccinations and infections play in achieving herd immunity. According to a model developed by PHICOR, a prominent public health research group, we could reach herd immunity as early as July, based on current vaccination rates. However, there are still many unknowns that will affect the path to herd immunity - such as the rise of new variants, or the risk of reinfection, or potential transmissibility of the virus by a person who has been vaccinated.
Even more important is the pace of vaccinations. Currently, about 1.7 million vaccinations are being administered in the U.S. each day. If the pace increases to 3 million per day (similar to the pace of flu vaccinations every fall), then herd immunity could be reached by May. In an Op-Ed published in the WSJ on Thursday, Dr. Marty Makary, a Johns Hopkins professor, went so far as to suggest that “there may be very little Covid-19 by April” if you assume, as he does, that two-thirds of the U.S. population have already been infected, a percentage I find difficult to believe.
The bottom line is, we are entering a new era of ambiguity. There will be no magic moment when it can be declared that the pandemic is over, especially when some mutations of the virus, like the one that originated in South Africa, are more resistant to vaccines than others. Ambiguity is the essence of scientific innovation … and we have to get comfortable with that notion. I, for one, don’t have a problem with it. The totals:
2/5 - 1496
2/6 - 1992
2/7 - 1112
2/8 - 925
2/9 - 1318
2/10 - 1401
2/11 - 1503
2/12 - 1097
2/13 - 1189
2/16 - 883
2/17 - 679
2/18 - 1198
2/19 - 847
2/20 - 774