Thread by @bencowling88

Hong Kong Citizen News have kindly agreed to publish my commentary on herd immunity. It's a long read, available here, grab a coffee: hkcnews.com/article/39405/… I published a similar commentary a few weeks ago in Chinese in Mingpao. I'll give a short summary in a new thread below

https://twitter.com/bencowling88/status/1365117246368976898

Herd immunity describes the situation where a high enough fraction of the population are immune that a large epidemic is no longer possible. Immunity can be acquired through infection or through vaccination (2/10)

In some parts of the world, herd immunity will be reached mainly through large numbers of infections. In other places like Hong Kong where infection rates have been kept low by successful public health measures, herd immunity could be achieved through vaccination (3/10)

Until Hong Kong can reach herd immunity, we won't be able to return to normal and stop all control measures. We could suppress "waves" and then temporarily lift measures when case numbers are low, but cases would rise again sooner or later (4/10)

We could aim for elimination like mainland China, Taiwan, Australia and New Zealand. But it's tough to get to zero cases, and it's tough to stay at zero cases, any outbreaks need to be quickly stamped out (5/10)

Higher vaccination coverage in HK would make elimination a bit easier, and an advantage of pursuing elimination would be the possibility of a quarantine-free travel bubble with mainland China or some other locations also aiming for elimination (6/10)

If we are able to achieve high vaccine coverage, we could drop all the control measures - no more closure of bars, cinemas, beaches, no more bans on social gatherings, no more contact tracing, no more on-arrival quarantines for persons arriving from anywhere in the world (7/10)

However, once we achieve herd immunity and reopen to the world, we would still expect COVID cases and outbreaks to occur from time to time, we wont expect COVID to disappear from the world time.com/5942246/elimin… (8/10)

That means that in this scenario, Hong Kong citizens likely might face the need to quarantine on arrival in mainland China or some other parts of the world that are still pursuing elimination, because those locations won't want to risk importation of infections (9/10)

For example, in mainland China, every small COVID outbreak in recent months has resulted in expensive lockdowns and mass testing exercises. Minimising introductions of infection is critical to maintaining successful elimination, and that requires on-arrival quarantines (10/10)

Should end the thread on a positive note - we have secured safe and effective vaccines and have the opportunity to get to herd immunity within 6 months. I’m looking forward to the chance to return to normal (11/10)