What isn’t herd immunity-Michigan.

Yesterday I discussed the example of Israel where social restrictions were kept in place until approximately a third of the population had vaccine-induced immunity. Below I include the graph documenting daily Israeli infections and vaccine percentages from yesterday for comparison with Michigan’s situation. 

The key here is that the social restrictions were not eliminated until the population had significant vaccine-induced immunity.  

For comparison, today I provide what happens when stringent social restrictions are removed without the population having significant immunity. It turns out that the state of Michigan has a population very similar to Israel’s. My colleague in the School of Information, Dean Tom Finholt, was kind enough to plot a graph similar to the Israeli data, but using Michigan’s daily COVID-19 infections and immunizations. The result is startling. 

Michigan’s restrictions were removed in mid-February after almost a year of enforced distancing along with closure of restaurants and schools. At that point in time, Michigan had only 5% of its population fully vaccinated and only 10-15% having received even a single dose.  

After release of restrictions, COVID-19 exploded so that by April 1st infections were six times the daily rate in mid-February. While the rate of vaccination did increase, it was slow and nowhere near the increase in infections. As late as April 1st the percent of the population with full COVID-19 vaccination was still less than 20 percent, only twice the level in February.

If there is any solace in these figures it is that the level of vaccination in the third week of April is now approaching the level in Israel when they released their social restrictions. That corresponds with the decrease in the number of daily COVID-19 infections over the past week. However, the numbers of new daily infections are so high that the beneficial effects of vaccines will take weeks to be fully impacted.

Improvements in COVID-19 infections in Michigan will also require more aggressive vaccination efforts with continual increases in the vaccination of the population. This would be a change for the state of Michigan, which currently has one of the poorer vaccine efforts in the nation. 

The take home lesson here is that social restrictions are a bridge to more definitive tactics, usually an effective therapeutic or a vaccine. If those approachs aren’t in place, one cannot expect continued low levels of infection after stopping restrictions. In Michigan, the strict social restrictions that ended in mid-February were, unfortunately, a bridge to nowhere.  

Published by jbakerjrblog

Immunologist, former Army MD, former head of allergy and clinical immunology at University of Michigan, vaccine developer and opinionated guy.

2 thoughts on “What isn’t herd immunity-Michigan.

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