How will the world vaccinate seven billion?

This is false, immunity is strong and long-lasting. The news is trying to sell papers. A vaccine is also an attenuated version of the virus so if becoming immune from the virus doesn't last long it won't last long from a vaccine.

I am also not sure how long it lasts but I fail to see why it will matter whether you got the immunity from a vaccine or the normal way.

And let's say everybody get vaccine in 2 weeks period of time, if the immunity doesn't last at least few years what's the point of this mass vaccination then.

FWIW, correctly or incorrectly, I just read the OP as saying that people who have already been infected might not need to be vaccinated because they already have been exposed. So that figure might be smaller than what the BBC is floating. Not saying that affects the challenge appreciably, just that I read it differently.

The ship has long since sailed for productivity missed.

Immunity doesn't last for the common cold because there's so many viruses that cause it.

The original herd immunity "estimates" of 60% were 1-1/Ro. This never considered heterogeneous spread and it assumed everyone was equally susceptible.

It's hard to estimate prevalance because PCR testing has a large false negative rate. It depends highly on which day of the infection you're tested and even then the peak rate is still quite miserable for trying to find it.

Serorevalence is also tricky as we trade off false positive for false negative and the antibodies decline after a few months. That's not to say that memory B cells can't spin up production on demand though. Then there's the whole t-cell response which may play a bigger role in asymptomatic cases. All in all, its understood that antibody testing is underestimating infection rates.

Regardless of what values we think herd immunity should have, it's pretty clear that places like Sweden have seen the death peak and then tail off without any major change in distancing policies. If anything, people are relaxing more with time.

edit: I should mention that since march, we do have better treatment options and we have stepped up our game protecting care homes all over the world including Sweden which saw a majority of deaths from those facilities. This is why it's important to look at trends in other countries as well.

Herd immunity is only going to be around 10 to 20% because of previous cross-reactivity with common cold viruses.

Sweden Italy and New Zealand have already hit herd immunity. They're done with the virus and didn't have 50 percent.

And before you post that they have a few cases recently... understand herd immunity doesn't mean the virus is gone...it just means the virus has nowhere to jump to... so there will always be a smattering of cases.

Hear hear!

Fair enough, of course any vaccine that does get distributed to billions of people should be tested very, very carefully. Chances are the first option might not be the best one (see the vaccine that's being rolled out in Russia).

But the article is talking about the logistics of distributing an effective vaccine, once it's found, not distributing the first best thing someone happens to come up with. It seems pretty likely that at some point a safe and effective vaccine will be found. Should that vaccine not be distributed widely?

Look at the death rates for people under 45...it's like 1 in 10,000. In some cities and for certain age brackets, you're more likely to be murdered or commit suicide than to die from Covid. The car accident fatality rate is roughly 1 in 10,000.

What are you talking about? What drowning? The clinical picture hasn't been that different compared to previous years with outbreaks of respiratory illnesses. In fact in some countries the death rates have actually been lower. The only reason this year we are talking about it is because for some reason it became a huge media thing. There was no reason previous years to not talk about respiratory illnesses. They have always been serious thing and people are dying each year from them. They have always been dangerous to elderly people and people with other illnesses. I feel like I'm living in a parallel universe all of a sudden.

If you travel, vaccinations are sometimes not optional, depending on the destination.

No, sorry. My body. My choice.

And all the other people with lots of in-person contact with others, like in retail, restaurants, taxis, etc.

And a lot of those who cram into public transportation during rush hour.

Otherwise you'll still overwhelm hospitals quickly in another runaway wave of infections.

They are a high risk group.

This is false immunity is strong and long-lasting otherwise they wouldn't be sinking billions into a vaccine which operates the same way that infectious immunity operates.

I'm not saying you shouldn't have the option... but there's plenty of us that understand how risk works.