As if herd immunity is the only way. Note that Australians and New Zealanders don't have immunity to a lot of things.

We're don't have herd immunity to Ebola. Instead we just don't let it take hold. We have 0 cases of rabies. It no longer exists in any animals. Cholera is almost non-existent. Occasionally a flight will come in that causes some alarm but that's it. Malaria only comes from people who traveled abroad. Our cows aren't immune to mad cow disease. But we don't have any cases here.

It's amazing what a bit of distance and quarantine can achieve. The two nations are also close to eliminating COVID-19 internally. Sure international travel will have to remain restricted but it's really not a big deal. Trade is still happening, just not tourism.

Those examples are either not very contagious or not contagious at all.

Yes. Ebola, for example, requires direct contact with the body fluids of an infected person. It also kills a high double-digit percentage of everyone who gets it. This makes eradicating it entirely both more feasible and much more important than a respiratory disease that can be caught just by being in the same room as someone with no symptoms, and that causes mild or even no symptoms in most people who get it. Covid-19 just doesn't have characteristics that make eliminating it entirely look like a feasible option.

And yet given the continuing 0 new cases of COVID in New Zealand it is manageable. The only risk is international visitors at this point which the article discusses in terms of both issues and solutions to an ongoing international travel ban.

>The two nations are also close to eliminating COVID-19 internally.

And all it takes is one person to coof somewhere in their country and bada bing you're toast. I don't see how this is beneficial, unless moving forward they has no travel period which is completely unrealistic.

Except that's not the case at all. It is easy to track and isolate a small number of cases. The New Zealand government listens to its advises who know more than you do.

New Zealand has had fairly strict lockdown measures even though new cases have been in the single digits for weeks. This suggests that they think contact tracing can't control even a small number of cases without extreme additional measures.

Can't control the number of cases at the moment. And New Zealand is planning to leave lockdown very soon

Because if we do that now hopefully we won't have to do it again.

That's my point. If your end goal is to have zero cases and not just a small manageable number, that will require severe ongoing restrictions - for example, probably no travelers from Europe or the US for years. It won't be just a matter of having good coronavirus infrastructure in place.

That's correct and that's exactly what the leadership of AU+NZ are discussing at the moment as per the article.

>The meeting discussed a possible "trans-Tasman bubble", where people could go between Australia and New Zealand freely, and without quarantine. But she said visitors from further afield were not possible any time soon.

Trade will still occur of course. There doesn't seem to be a documented risk of COVID spreading via cargo ships. Tourism is the issue.

The hope is that since AU/NZ have more or less as much outgoing tourism as they do incoming tourism the economic damage from border closures can be mitigated by directing tourism internally and bilaterally. New Zealand has been at 0 new cases for days now and Australia seems to be just a couple of weeks behind on getting COVID-19 to zero new cases. There were 24 new cases in Australia yesterday but that's far away from the peak 500+ they had in March. So it's a possibility.

The only risk to these two nations is foreign travel sparking a new wave of infections. So foreign travel will have to be restricted. In all other respects life will go back to normal. I don't think the same is true of any other nations in the world right now. Nowhere else will you be able to live normally without that risk.

Seriously if the best negative anyone has against the quarantine is you'll have to continue to restrict international travel now that you've literally got the number to 0 new cases you've lost me. That's such a small price to pay.

We can have travellers from anywhere, they will just need to accept two weeks quarantine. It's not perfect but it's better than no travel at all.

>We're don't have herd immunity to Ebola. Instead we just don't let it take hold.

Well, COVID-19 isn't Ebola, and it has taken hold, and we are under lockdown. So what are the conditions for reopening? Vaccine?

> it has taken hold

New Zealand had zero new cases yesterday. Zero. Australia had 24 new cases and trending to zero.

I'm not sure which timezone you're in but, yesterday (Wed 6 May) in New Zealand we recorded one confirmed case, one probable case and one death.

We still have a ways to go before we're out of the woods. We have some reassuring signs though (many consecutive days of < 10 cases detected).

Pretty stupid to develop herd immunity for a virus when you don't even know if herd immunity is possible, or any immunity for that matter.

How can a vaccine ever work if it's impossible to develop immunity by reacting to it?

An example with tetanus:

> Unlike many infectious diseases, recovery from naturally acquired tetanus _does not usually result in immunity to tetanus_. This is due to the extreme potency of the tetanospasmin toxin. Tetanospasmin will likely be lethal before it will provoke an immune response.

Quoted from https://en.wikipedia.org/wiki/Tetanus. Emphasis is mine.

That's an unusual situation that probably isn't relevant here. The way that tetanus vaccines work is that they cause the immune system to destroy the extraordinarily neurotoxic tetanospasmin toxin. It's impossible to get a natural immune response because, as the article points out, anyone with enough of it to trigger an immune response is dead. Coronaviruses triggers immunity just fine, the immunity just doesn't last and we don't really know why.

If there are many different strains loose in a region that don't confer immunity to each other and immunity only last a year people could be perpetually sick with the virus. A vaccine combines a variety of weak or inactive strains that give your immune system a big picture view of the virus to develop a comprehensive response to COVID-19 instead of COVID-19 Strain 93A.

The flu vaccine works the same way: scientists predict which strains are the most likely to spread and create or find weaker strains that are all combined into a single vaccine.

That's an interesting and important point. Luckily it seems to mutate 10x slower than influenza viruses and so far no different strains have been found. Finding new strains would also thwart some of the current work on vaccines being done.

https://www.theatlantic.com/health/archive/2020/05/coronavir...

I was being a bit imprecise when using the phrase "strain." In the context of virology in general, a strain is delineated by a difference in functionality - i.e. some key component of how it infects, replicated, or damages the body is different from other known cases. However, in the context of vaccines, a "strain" may function the same but might not produce some unique protein or other marker that the immune system uses to identify the pathogen, without having an effect on the rest of the virus.

COVID vaccine work is still in its infancy so we don't know yet whether the non-functional mutations we're seeing in COVID's phylogeny will effect how effective vaccines are.

There is no guarantee that a vaccine is possible.

Exactly what I'm getting at. They tend to use similar mechanisms, though vaccine being the more or less completely safe path.

What could alter the course though is if some treatment is found which makes it essentially harmless, even if immunity would be impossible.

Herd immunity hasn't been achieved anywhere and with around a half percent infection fatality rate that doesn't seem like something you would like to get to.

It’s lower than half percent now. Around 0.2-0.3% and probably going to go even more lower.

any source? I know that many people who have it don't go to hospital unless severe (have few colleagues like that), plus tons of +-asymptomatic folks, but these are just words, no hard data

Source from April 25:

https://www.nbcnewyork.com/news/local/2-7-million-in-new-yor...

> With 271,000-plus confirmed cases, the mortality rate would be as high as 6 percent. With 2.7 million cases, it would be around 0.5 percent -- much lower, though still much higher than the seasonal flu.

0.5% in New York as of April 25. Since New York is the worst case so far in US, overall, the fatality rate drops to 0.2-0.3%.

You say:

> I know that many people who have it don't go to hospital unless severe (have few colleagues like that), plus tons of +-asymptomatic folks

That's exactly why the true mortality rate is much LOWER. Mortality rate's denominator is supposed to be the true number of infected. So asymptomatic and others with anti-bodies means the true denominator is much higher and thus the true mortality rate is much lower.

It's much higher than than. New York had an ~1% IFR.

Source from April 25:

https://www.nbcnewyork.com/news/local/2-7-million-in-new-yor...

> With 271,000-plus confirmed cases, the mortality rate would be as high as 6 percent. With 2.7 million cases, it would be around 0.5 percent -- much lower, though still much higher than the seasonal flu.

0.5% in New York as of April 25. Since New York is the worst case so far in US, overall, the fatality rate drops to 0.2-0.3%.

You say:

> I know that many people who have it don't go to hospital unless severe (have few colleagues like that), plus tons of +-asymptomatic folks

That's exactly why the true mortality rate is much LOWER. Mortality rate's denominator is supposed to be the true number of infected. So asymptomatic and others with anti-bodies means the true denominator is much higher and thus the true mortality rate is much lower.

It's much much lower than that now. The numbers we've been fed to justify this quarantine are not real.

Just stop. We've seen what happens when this virus is let loose. We've seen it collapse the Italian healthcare system. It almost came close to collapsing the healthcare system in NYC. So it isn't just a big conspiracy to quarantine everyone. The initial numbers were higher, but that's expected given the lack of data. The new numbers are better but still flawed. We won't know the true infection rate and the death toll for a while still, but the models are constantly refined.

Eh it's just as well, NZ could use an environmental breather from all the tourism. Silver linings.

Maybe. The effects of a weakened economy often mean a switch from caring about the environment to caring about bottom lines. It's harder to push green regulation when compliance costs will cause job losses.

So cause damage and then try to fix it vs don't cause damage in the first place?

Unfortunately tourism is often what makes the environment justify its opportunity cost when it isn't an effective "local service". It isn't great for economy, workers, or the environment but it is a very workable compromise that is better off than the worst case for all three.

Even in countries hit hard by it, those will not develop herd immunity because there are enough people able to work from home.

This is especially true in affluent tech hub areas like Silicon Valley and Seattle. So even if the country hits the 0.7 infection rate threshold (or whatever), it's still unlikely to be able to open completely.

They wait until a vaccine is available. That is obviously what they are shooting for using this tactic.

It's actually very smart. You can try to achieve herd immunity if vaccination proves nearly impossible, but why not wait and see while you can?

>but why not wait and see while you can?

Wait for how long? We've never turned around a vaccine in under 18 months, and some pathogens don't have vaccines and have been around forever. What if it takes 24 months to develop an effective vaccine? Do we lockdown for that long?

You quarantine for that long. NZ is easily isolated, and self sufficient. As long as the deaths keep mounting elsewhere in the world NZ populous might be happy to have no international flights for 24 months.

Herd immunity isn't a thing for coronavirus yet.

Herd immunity only works when you have an effective vaccine/treatment, and it only helps the people who aren't eligible for that treatment. Given the coronavirus R0, you might achieve herd immunity when 75% of the population has been infected. Achieving herd immunity by letting the virus slowly spread until 0.5% or 1% of your people to die is a loss condition, that's millions of deaths. It's certainly better than letting it spread like wildfire and overwhelm hospitals so that 5% of your people die, no question there, but still not good.

The alternative is indefinite lock down and lots of prayers for an effective vaccine?

Not indefinite lock down, but tight border controls. There are only a couple of hundred active cases in NZ currently. We are looking at exiting from our stricter lockdown next week.

It buys time to prepare, and for vaccines and other treatments.

Yes, this point is being strongly overlooked. Worst case scenario they end up like the rest of the world now with a struggling economy and thousands of cases.

By closing their borders it gives them time to build up their healthcare infrastructure, wait for vaccines and other experimental treatments to be vetted so by the time their borders open up again it won't devastate the country like it has everywhere else. These are all luxuries every nation wishes it could have taken advantage of. Criticizing New Zealand's response right now is extremely premature.

Isn't tourism a large portion of the economy there? I'd imagine this isn't going to help. Although no one is really traveling now, so maybe the damage is already done.

For New Zealand the largest source of tourists are from Australia. The opposite isn't true due to the nations population imbalance but New Zealand is still a large source of tourism for Australia.

It may surprise some people but the number of Australians that visit countries overseas is roughly equal to tourists visiting Australia. As wealthy diversified nations tourism for Australia and New Zealand is a net wash in terms of foreign cash flows. Citizens spend as much overseas as tourists coming to Australia. The issue isn't foreign currency gains/losses but a more simple case of the economy and jobs are setup to service a certain number of tourists who are no longer there.

Both nations leaders have met and discussed encouraging bilateral tourism. Honeymoons, family overseas trips, etc. will be bilateral and internal for the time being. If the previously external tourism can be directed internally it'll actually more or less be a wash on topline numbers.

Over thousands of years, no herd immunity has ever been developed for smallpox, measles, chickenpox, or various other diseases.

Only vaccine development allowed the creation of any level of herd immunity. There’s no such thing as “natural herd immunity” in the real world.

Whether or not "herd immunity" is the right term, Europeans were sure a lot better protected against smallpox than the inhabitants of the Americas were when said Europeans arrived and started spreading the disease.

nor coronaviruses, those pesky colds stay with us because the antibodies don't last

That's absurd. Why do you think that a particular smallpox or measles epidemic dies out? Because enough people have been infected in a given population that it can no longer spread in that population.

That doesn't mean the disease will go extinct, but the epidemic will end in that population. Flare ups can still happen among sub groups of people in the population who aren't immune but the disease won't spread rapidly through the population as a whole until the number of people who are immune drops below the herd immunity threshold for that particular disease/community.