The recent focus on reaching herd immunity through vaccination may be overblown.

My modeling suggests that it is increasingly unlikely that the US will reach the immunity levels required for theoretical herd immunity in 2021.

https://t.co/7jDgND5vE1

(A 🧵 w/ my thoughts)

This conclusion is based on the following new developments over the past month:

- Remained high levels of vaccine hesitancy
- New variants that may lower vaccine efficacy
- Rollout of the J&J vaccine (efficacy ~70%)
- Delayed arrival of the children vaccine

That said, herd immunity does not have a hard threshold, and being close to herd immunity may be sufficient to prevent large outbreaks.

Our goal should not be to reach "herd immunity", but to reduce COVID-19 deaths & hospitalizations so that life can return to normal.

From my recollection, this was the goal last year, to have a vaccine that would reduce deaths and strain on our healthcare system.

But now the messaging has shifted to "getting at least X% of the population vaccinated in order to reach herd immunity".

I believe this new public health messaging that herd immunity means "X% of people vaccinated" is flawed.

It seems to ignore the fact that:

1) Vaccines do not provide 100% immunity
2) Nor do they stop 100% of transmissions
3) ~30% of population have already been infected