Originally Posted by Varrok
What's the deal with this whole herd immunity, anyway?
In theory, if enough people have immunity to a virus, it means that any time the virus enters the population, it'll hit a dead end of people who are immune and thus won't be able to pass it on. So then, if there are people who don't have immunity they won't catch it because the virus is unlikely to reach them.
Details vary for virus to virus. But to give an example, if 90-95% of the population have the measles vaccine, it's very unlikely that the remaining 5-10% of the population will catch it. If everyone who could take the vaccine had it, that 5-10% would be made up only of people who are immunocompromised and thus can't take the vaccine, as well as the small percentage of people who receive the vaccine but don't gain immunity.
It's not a sharp target number though. The larger the percentage of people who have immunity, the less the virus will spread. It's just that a certain point it becomes almost an impossibility.
But that's just context on the concept of herd immunity. In the case of COVID-19, anyone who suggests we should aim for herd immunity right now is willfully ignorant and dangerous. The fact is, we don't yet know that catching COVID-19 even grants you significant levels of immunity, and if it does, how long that lasts. What we do know is that other coronaviruses tend to only have immune responses that last for months, which is not enough to give any real protection. In the case of COVID-19, we know that not everyone who catches it has a measurable immune response; people who have been tested positive while they were sick were then given antibody tests later and came up negative. It is also thought that the many asymptomatic carriers of the virus are less likely to have a measurable immune response, which may mean that they could then catch it again and again and pass it around multiple times.
To summarise; given the number of things we don't know about COVID-19, and given the few things we do know about it, it is clear that the concept of herd immunity through widespread natural infection is likely impossible, and anyone who suggests it is, as I said before, willfully ignorant and dangerous.
And to add to that that anyone who says 'It'll just be a couple of old people who die' is really, completely full of shit. Plenty of young folk have died. And even if the death rate were low (which it isn't), the number of people who have long-term, serious side effects is seriously worrying.