A cluster randomized trial of HEPA filters is strikingly negative

Another failure of public health 'experts'

During the pandemic many public health researchers said we should spend hundreds of millions of dollars adding HEPA filters to schools and homes. In some cases, this was their entire professional work.

I had my doubts. There are a million reasons why this hypothesis might not work. Most notably, that, in the course of our day-to-day lives, we eventually will go someplace that doesn't have filtration. Additionally, it might not work as well as you think. Some air, or pockets of air, will be unfiltered. Instead of spending millions, we should study these interventions in cluster randomized trials-- that was always my position.

Here are some receipts.

Well, it appears we have more evidence.

I was going to summarize the randomized trial, but my sensible medicine colleague John Mandrola did that superbly

https://www.sensible-med.com/p/lessons-from-the-hepa-filter-rct

The authors chose a nursing home population— I.e. if this intervention is going to work anywhere, it should work here. Here's what they found

Per Dr John

• There was no evidence of a difference in the number of respiratory infections per winter per intervention vs control bedroom residents (0.99 vs 1.04; adjusted incident rate ratio, 0.92; 95% CI, 0.64-1.33; P = .67).

To my knowledge, and a reader can correct me if I'm wrong, no one has shown a benefit to having these filtration systems on any clinical endpoint, in any setting, in cluster randomized or randomized fashion.

In my opinion this story illustrates the two most important lessons of modern medicine

1. The greatest source of misinformation— i.e. the most damaging and least likely to be questioned— comes from experts, frequently quoted in the mainstream media. These experts are far more dangerous than random people on the internet who also hold incorrect views precisely because the latter group is vigorously questioned and the former group is not.

2. I place zero trust in public health experts. There's no qualifications to that. I wouldn't trust a single thing they said if I cannot independently verify it. These days, the distorted claims are too many to count. Everyday I open the newspaper and I see every story is incorrect. Wild! I wrote about one recently for the Free press.