The WHO says that we can't assume someone is 100% guaranteed to be immune when they have antibodies. That's true, and it's an important flaw in the idea of immunity passports that they're tackling - you couldn't send people with immunity passports into quarantined nursing homes or allow them to attend potential superspreading events.

Herd immunity doesn't require perfect immunity or a 100% guarantee of it. No reasonable expert doubts that herd immunity is possible, although some argue it's too costly.

The key part of that press release is:

> As of 24 April 2020, no study has evaluated whether the presence of antibodies to SARS-CoV-2 confers immunity to subsequent infection by this virus in humans.

The most likely thing is that it does mean immunity, but the WHO isn't going to say that without clear evidence.

No-one is assuming - we are weighing evidence and there is far more evidence that it does provide at least some immunity than none - it seems oddly disingenuous of WHO to make statements like this because they know how it will be interpreted.

That doesn't mean it doesn't, it just means it isn't scientifically proven yet.

You can be reinfected. It sounds like there's already some evidence suggesting that reinfection is at least significantly less likely than initial infection.

Not sure why I am getting downvoted, I guess covid-19 shaming is a thing. From what I've read people who appear to get it again is actually just a relapse of the original infection[1].

[1] https://thehill.com/changing-america/well-being/prevention-c...