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Let’s just take a moment today to talk about why a lot of experts ( @devisridhar, @BhadeliaMD, @sarahcobey, @neil_ferguson, @joshua_schiffer and more) think the pursuit of natural herd immunity for COVID is a really bad idea, and why they also believe it won’t work. 
First, the concept: if enough people get infected with COVID and recover, and if they’re immune for the long-term, then the virus burns out. The tipping point is generally thought to be between 50-80% of a population would have to contract coronavirus for this to happen...
The idea was floated early on in the pandemic (Boris Johnson described it as the “take it on the chin” approach). But it was quickly abandoned by most nations because it would likely cause hundreds of thousands or even millions of additional deaths.
And experts now think the cost of millions of COVID infections is higher still—it’s become clear that a large number of those who recover have long-term health effects from the virus. Nobody knows how long, but that is an additional burden on the health system.
Sweden came closest to chasing the herd immunity dream. They limited large gatherings but kept shops and schools opened. The result? Overall infection rates, according to blood tests, rose but not that much …
Meanwhile Sweden’s nursing homes were hit hard. Their death rates are far higher than other Scandinavian countries.
Their economy has done a little better, but not hugely better, than nations like Germany, which have taken a more aggressive approach. https://www.npr.org/sections/coronavirus-live-updates/2020/08/06/899776725/sweden-records-largest-gdp-drop-since-1980-but-outperforms-many-other-eu-countri
Their economy has done a little better, but not hugely better, than nations like Germany, which have taken a more aggressive approach. https://www.npr.org/sections/coronavirus-live-updates/2020/08/06/899776725/sweden-records-largest-gdp-drop-since-1980-but-outperforms-many-other-eu-countri
Why has COVID not moved quickly through the Swedish population? One simple theory is that people don’t want to catch it on an individual level… nobody wants to be part of the "herd."
But another issue may be that the immune response to COVID wanes with time. Antibodies might fade. The past few weeks have seen the first confirmed cases of COVID reinfections. https://www.statnews.com/2020/08/28/covid-19-reinfection-implications/
If people can get COVID multiple times, even if the second infection is mild, that makes herd immunity without a vaccine impossible. We still don’t have the data to know, but we will in coming months.
Natural herd immunity may have always a little bit of a pipe dream anyway. The experts I spoke to couldn’t come up with an example of a disease that got to herd immunity without a vaccine. Chicken pox, for example, circulated (mostly) in children until the vaccine.
What’s more likely is that COVID becomes endemic. The huge waves of infections might end, but the virus will continue to circulate, and sicken people, for a long time. (n.b. A vaccine will still be a game-changer and help a whole lot). https://www.npr.org/sections/goatsandsoda/2020/06/08/872470111/noting-like-sars-researchers-warn-the-coronavirus-will-not-fade-away-any-time-so
There’s more here: https://www.npr.org/sections/health-shots/2020/07/24/894148860/without-a-vaccine-researchers-say-herd-immunity-may-never-be-achieved
And #nprshortwave did an episode (in case you’re tired of reading).
Also @maddie_sofia is an immunologist, so maybe you'd like to get your facts from her instead of a physics reporter? https://www.npr.org/2020/08/07/900323554/why-herd-immunity-wont-save-us
Also @maddie_sofia is an immunologist, so maybe you'd like to get your facts from her instead of a physics reporter? https://www.npr.org/2020/08/07/900323554/why-herd-immunity-wont-save-us
