We only need to stop some Covid, to stop all Covid. Going back to Jeremy’s work nearly 4 years ago, on masks.…

We only need to stop some Covid, to stop all Covid. Going back to Jeremy’s work nearly 4 years ago, on masks. But the same applies across most aspects of Covid. /1 https://t.co/AEBgD00M7b

The expression ‘making the perfect the enemy of the good’ applies to public health too I think. There’s a constant conflation of individual and collective measures. /2

A perfect fit-tested mask example is a must for a health professional in a high-risk situation all day. For others, even if everybody wore poor masks, we would make massive inroads against Covid. /3

The key to beating any infectious disease isn’t in the protection we can devise for individuals (though that’s always desirable). It’s in how much we slow transmission. Which we do by reducing (only rarely eradicating) viral load in individuals. /4

You just need to reduce transmission enough that Rt < 1. Then exponential decay will do the rest, for us. A sub-optimal mask worn widely is a powerful weapon to help achieve that. As is a sub-optimal vaccine. /5

‘Sterilising’ vaccines are that individual focus again. Most vaccines that end epidemics and pandemics are not sterilising. They don’t need to be. They just need to slow transmission to Rt < 1. By *reducing* viral load in the unfortunate infected. /6

Then maths does the rest, for us. And with a virus like SARS2, with its dispersion characteristics, this is even easier. Because most people aren’t spreading the virus anyway. /7

Just a handful of superspreading hubs. Again, we don’t need to track down and eliminate Covid everywhere. Just to slow spread from the infected, in this case in hubs. /8

Maths will do the rest. We make the perfect the enemy of the good when measures get sucked into the team sports of society. Imitative rivalry. /9

Social media groups on efficient housing are another example. Those groups are often obsessive about turning every home into some sort of frightening self-contained utopia. The individual focus. But we only need most people to be quite a bit more efficient. Not perfect. /10

Similarly cycling groups often rapidly escalate into the imitative rivalry warfare of ‘gear’. Bikes, suits and helmets worth thousands. Who can have the coolest gear, etc. /11

Social media accelerates and encourages this sort of imitative extremism, leading to utopian metrics. But again, collectively we mostly just need to all be a bit better. Maths does the rest. /end

P.S. this *absolutely* applies to air purifiers too. They don’t need to be the quietest, to have the most efficient HEPA filters. They just need to reduce transmission. Maths does the rest. Maths and time, just keep them running a bit faster and longer.