Sunday was a NINE Green Arrow Day.

Herd Immunity Factor Explored

Good Morning,

Sunday was a NINE Green Arrow Day; below are the particulars.

In the USA, we have now administered almost 229 million doses as of March 25, 2021, 19 million more than the previous week. Of which, 95 million have completed their entire regime. The vaccine distribution continues to expand (more outlets), and the restrictions of access such as age have been lifted. Almost 28% of our citizens have completed the dose regime.

The combination of the 94.7 million-plus the recorded (32.5 million) and unrecorded (73.9 million) recovers make our Herd Immunity Factor (HIF) 201.1 million or 61% of our population. More than half of our citizens are safe.

However, one astute reader asked us if we are potentially double-counting because many that have had the virus have also had the required number of doses. We agree, and that’s why we modified our calculation. The current approach reduces the number of recorded recoveries by the same percentage of those who have completed their respective shots compared to the US population. The graph below shows the reduction of recorded recoveries by 28.5% or 9.3 million. Our revised HIF is now 191.9 million, or 58 %. Notice how the yellow-green recorded recoveries area on the graph is shrinking by eliminating double-counting.

We will continue using this method until we discover a better way to estimate the HIF. By the way, the CDC believes that at 70% to 80%, we will be at the long-sought herd immunity.

As for new cases, there were 77,100 fewer cases this past week, a 16% drop from the prior week.

We see this trend continuing.