CNN News:部分国家考虑发放"免疫护照" 世卫组织发出警告

We start off the week with a bit of a follow up to a story we covered last week about possible herd immunity in Sweden. When there's no vaccine for a disease like coronavirus, herd immunity can occur when enough people have gotten it, recovered from it and are then immune to it. A Swedish disease expert said there are signs of herd immunity appearing around the capital Stockholm. But one of the challenges of the new coronavirus is that it's still mysterious.

There's a lot that researchers don't know about it. And the World Health Organization, which is part of the United Nations, says just because people have recovered from COVID-19 does not mean they're immune to it. Some governments around the world are considering giving out "immunity passports" to people who've recovered from coronavirus. This would let them continue with normal life without as many restrictions as other people might have. But the World Health Organization says that's not a good idea because it doesn't have proof that surviving COVID-19 means people are safe from getting it again.
Is it possible that they are? Yes. But researchers don't know if the antibodies people may have give complete or just partial protection from coronavirus. And they don't know how long those antibodies will stick around in someone's system. These are the reasons why many health officials are telling people to continue keeping their distance from others even if they've had coronavirus and made a full recovery.