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According to the signatories of an open letter called the Great Barrington Declaration, lockdown does more harm than good. Should we really ‘open up society’ and let the virus rip? As it turns out, herd immunity is scientifically illiterate, the last thing we want to do.
The idea behind herd immunity
The Great Barrington Declaration claims herd immunity is all about ‘focused protection’. The authors suggest the most vulnerable people shield themselves from society, leaving everyone else to ‘immediately be allowed to resume life as normal’. The theory says this will allow herd immunity to build up.
On one side we have mainstream scientists who view lockdowns as the only way to keep a lid on the pandemic while we wait for vaccines to be rolled out. On the other side we have libertarians who say the damage done by lockdowns to economies and people’s lives is a price that’s too high.
On the face of it you can probably see both sides. The thing is, there’s a fundamental problem with the Declaration. It makes ‘extremely dubious’ claims about herd immunity, something absolutely central to the strategy, and badly misunderstands the science.
How the Great Barrington Declaration gets the science badly wrong
Herd immunity is a simple enough concept. When enough people become immune the whole herd is protected because infectious people rarely come across a person who isn’t immune. As a result the virus dies out.
Sadly this is far too simplistic.
The level of individual immunity you need to reach herd immunity depends on how infectious the virus is. Measles, for example, has an R number of about 15 and a herd immunity threshold of 95%. Coronavirus has an R number of around 3.5 and a herd immunity threshold of 60-70%.
So far the human race has only ever achieved herd immunity via vaccination. The Declaration recommends natural immunity. This would mean letting 66 – 75% of people catch the virus. And that’s where things get messy. Even if the death rate is less than 1% the virus will hospitalise and kill many millions of us.
Worse still, there’s absolutely no guarantee widespread individual immunity will automatically mean we also end up with herd immunity, because herd immunity only happens when the immune response completely stops people from picking up and transmitting the virus. This happens sometimes but by no means always. Much of the time an immune response stops us from falling ill if we catch the virus a second time, but it doesn’t stop the virus’s onward transmission. The same goes for vaccines.
There’s more. We still don’t know if natural immunity to SARS-CoV-2 or the experimental vaccines will stop the spread. Until we know for sure, the herd immunity theory is nothing short of scientifically irresponsible as well as deadly.
Last but not least, the Great Barrington Declaration doesn’t take the terrible effects of Long Covid into account.
It’s clear the people who signed the Declaration have totally failed to grasp the concept of herd immunity. Please don’t make the same mistake.