As insane as it seems I imagine we'll see closed borders in many countries for a long, long time (months, maybe years?). It's going to be very hard to justify risking even a small chance of introducing additional virus cases if you've just spent the last few months trying to get a point where even minimal non-"essential"* can begin to reopen there's going to be very little support for any increased risk of any kind.
*I put "essential" in quotes here because I believe the definition of essential changes the longer services are closed. For instance, a dentist isn't really essential when they're closed for a month, but a 3 month closure is going to be increasingly problematic for people needing something more than a standard cleaning.
Years? IMO, looking at the stats of Western European countries, who are all slowly lessening restrictions, typically showing both carrot and stick (“we think x will be allowed again in w weeks, if you all keep following the rules”), unlikely, at least not for countries with significant tourist industries. They will feel pressure to allow tourist visits, certainly from ‘safe’ regions such as Australia and New Zealand.
(Whether those tourists will go on holiday is another question. Tourists may be wary of going far away on holiday, and if social distancing will be compulsory inside planes, and trains, travel likely will become much more expensive)
It also will be hard for countries to withstand the pressure from their population to allow them to go on holiday in other countries.
In the end, the better choice may be to allow some tourist visits, as that may mean people will follow restrictive rules better than when they wouldn’t be allowed to have go on holiday/to make some money from tourism.
> They will feel pressure to allow tourist visits, certainly from ‘safe’ regions such as Australia and New Zealand.
As a New Zealander, I'm not sure that there would be much appetite for visiting any country outside this potential trans-tasman bubble for tourism purposes as we would be looking at a two week quarantine on returning home.
i don't think there will be much pressure from people wanting to leave. there are plenty of alternatives to go on holiday. how would that work anyways? people could complain or protest against local issues, but against a foreign country? which one? everyone wants to go somewhere different. rally up, pick a target and stage a demo infront of that country's embassy?
pressure is only going to come from inside from the tourism industry that is loosing out on income.
I imagine the tourism industry will suffer to some extent, but if NZ/AU residents are essentially restricted from traveling outside that zone, you may see an uptick of travelers who would have normally traveled outside that zone now choosing to vacation inside those two countries instead.
The UK currently has nothing to fear from open borders: why worry about the risk of a planeload of cases when there's ten new planeloads* of homegrown coronavirus every day?
Everyone else, however, may well have something to fear from the UK...
> But it, too, has "flattened the curve" of infections.
It‘s sad that the article uses the term in such a sloppy way. NZ was aiming for containment and eradication from the beginning.
There are three common strategies to fight the Corona virus:
„Herd immunity“ - Naturally letting it run out of steam. The problem is that your health system might get overwhelmed. Therefore „flatten the curve“. Advantages: new infections imported from abroad don’t matter; cost of the counter measures to society is minimized.
Disadvantage: virus damage is maximized.
Sweden is the classic example. GB, NYC probably.
„Dancing“ - try to keep the numbers low but live with fact that you cannot eradicate the virus. If necessary bring the cases down by using the „hammer“ first. Advantage: imported cases can be contained; possibly time will bring better treatment/vaccination. Disadvantage: expensive measures for indefinite time.
JP, HK
Eradication - Advantage: back to normal if achieved. Disadvantage: not robust against imported cases. Possibly very expensive/unachievable.
NZ
As one can imagine, changing from one strategy to another at first gives you the disadvantages without the advantages.
For reference both Australia and New Zealand each have fewer than 1000 active COVID cases right now, many from a cruise ship, The Diamond Princess that was allowed to dock in Australia. There's very few new cases appearing each day and of those new cases there's no surprises and they are traceable to the source. It makes sense for these two nations to trade and have tourism internally and bilaterally.
A source of current numbers of active/new cases: https://www.worldometers.info/coronavirus/ It's quite clear that both nations are close to extinguishing COVID-19 within their own borders.
The reason for this is both nations closed the borders early back in February.
When that happened the fuckwit Tedros Adhanom Ghebreyesus, director-general of the World Health Organization came on national TV of Australia and said "There's no reason to restrict travel". This was in February.
Listen to the fuckwit say it here: https://www.abc.net.au/radio/programs/pm/is-closing-borders-...
Lawrence Gostin, an official in WHO is also quoted in the above "it is unlawful, unnecessary and in breach of international law".
I normally wouldn't be so harsh on criticism but this was in February. The border closure wasn't some racist Donald Trump style effort. It was two countries doing the right thing but the WHO is so corrupt and fucked up they tried to stop it, even threatening they'd bring the border closures to the international courts.
Entertainingly, the Chinese government also tut-tutted about our border closures as being racist. Since then they have implemented border closings of their own.
Speaking of fuckwittery, the Diamond Princess debacle is really in a class of its own. There's some suspicion that it's also linked to (one of?) our worst fatality cluster in that medical personnel from the Diamond Princess may have gone to a eldercare facility straight after. Nice.
As far as I'm concerned, every cruise ship that docks in Australia can pay $1M for the right to not be greeted with an Exocet missile until that industry has paid back the hideous damage it's done.
depends on the country. in china everyone has to go into quarantine, and i believe i heard the same from germany too. i expect it will be the same in many other places
But there will be a time before COVID19 and after and they will be different in many ways we can‘t know, yet. I myself have this feeling of “One day the vaccine will be there and everything will be as it was before“. That‘s wrong I think, we already left the known track and while a vaccine-like intervention will come, it will not get us back into the timeline we were in, before.
Yeah it's likely that could be true. Here in NZ we've not yet been hit by the economic toll as the government is paying wage subsidies. That's a short term fix. Years of high taxes will follow. Job losses will mount as the tourism sector falls over.
It will not be pretty. So was it a wise move to shut down? Maybe, given the information they had at the time. Better to be safe than sorry. In hindsight with all the facts we have now maybe not but they didn't have those facts at the start.
How do you mean? They likely will have much higher deaths -- only if they decide to quarantine longer could I imagine that they have a success -- but "not handling covid 19 well" does not mean they will quarantine longer or that they will do a good job after their bang-up job.
It feels deeply wrong to cold-heartedly choose a course of action that will result in the death of many people and the resulting suffering of those who survive their loved ones.
But people are resilient. People face death from other causes all the time. Yes, there will be a measurable increase due to covid-19 but in countries that are already ravaged by poverty, crime, disease, wars, etc, it might not significantly alter the emotional balance of those who survive. That's particularly true in those countries whose authorities successfully downplay the effects of covid-19, e.g. by not doing much testing.
From that POV, all other things being equal, one could expect that those countries might grow their economies while the rest of the world loses opportunities.
I'm not sure I buy that argument though. World economy is not entirely a zero sum game
I wasn't implying that nations should choose this course. But say a year from now when most of their population is immune and the disease is no longer worrisome within that nation (relative to the zillion other things you can die from), then from that point they my ironically be better off.
Of course this assumes
1. some kind of immunity (which I'd think indications are pointing toward, or I'd expect to have seen more repeat contractions by now)
2. the response was dorked up down to the individual level (which is most decidedly not the case -- plenty of individuals (especially among highish-income) are choosing to self isolate and take precautions, and thus will not contract the virus for quite some time no matter how bad the government response was, so immunity within these groups will never form, so the government will not be able to reopen anyway)
So even in the absence of other considerations, the 2nd point above pretty much cancels out my original post.
>> 1. some kind of immunity (which I'd think indications are pointing toward, or I'd expect to have seen more repeat contractions by now)
Not necessarily, you can have a short-term immunization that only last a year or two. This is why the "herd immunity" might be a poor idea when we don't know much about this virus.
Anyway, i demanded a work/vacation visa to NZ for this October, i fear this won't be possible :/
Ask Ireland or its overlords how choosing short term economy over people worked out for them with the Irish Potato Famine. Andrew Carnegie became wealthy in the US instead of generating income for the UK - regardless of one's opinions of his overall morals or lack of them he was far more productive than the harvest they sold.
That was a more extreme case of 20% to 25% of the population but losing a sizable percentage of productivity with the population is very expensive in ways apparent both on and off the balance sheets. It is the epitome of penny wise pound foolish to make such a trade - the bloody gains will fade away in time while the loss echoes.
This feels like it's based on a lot of "gut feel", though I appreciate he devils-advocate argument. Specifically, these points:
> it might not significantly alter the emotional balance of those who survive. That's particularly true in those countries whose authorities successfully downplay the effects of covid-19, e.g. by not doing much testing.
Most countries in the world rely on global supply chains, and many countries are now closing their borders to external trade, meaning that their own prices will sky-rocket, likely causing layoffs and bankruptcies, causing stimulus packages and therefore inflation. The world is very interconnected (as I'm sure you know)
In addition, I believe that many people would suffer significantly _more_ if many more people were dying around them. They would have friends and family who died or who were tied to people who died. I don't think it would be something as simple as "eh, someone else's problem". In addition, it's not just deaths -- there is a lot of data showing that there are long-term lung issues that develop if you do survive.
> Most countries in the world rely on global supply chains, and many countries are now closing their borders to external trade, meaning that their own prices will sky-rocket, likely causing layoffs and bankruptcies, causing stimulus packages and therefore inflation
Which countries, exactly, are closing their borders to trade? There are definitely a lot of restrictions being placed on travel and tourism, but banning cargo makes no sense in this context.
If anything, things will probably just get lonelier for merchant seamen.
Herd immunity is commonly not well understood in my opinion by the general public. All it means is the point where the spread is no longer “viral” — as in for ever person that’s infected, that person infects less than 1.0 people. People still get infected, die, etc.
Higher the true R0 value for the virus, higher the threshold for reaching herd immunity and the eventual point the infection rate reaching 0.0; globally, without a vaccine, very possible corona will continue to exist years, if not longer.
We've already proven you can go from one case to worldwide pandemic in 3 months. So all it takes is one case somewhere in the World, and you'll never be able to reopen borders.
Now if a fully functional vaccine is developed, that'll of course change things. But there's no guarantee one is possible, so only time will tell.
I don’t really understand how so. Countries that have handled it aggressively at least have the option to open borders and allow the virus to spread if they felt like that would for some reason put them in a better position. But this way they can hold off for a vaccine or effective treatment and have a far better outcome.
The concern is that they might not have that option. A politician would have to be extraordinarily brave to get on TV and say "we've decided we should let the Americans come give us coronavirus".
The countries that are ruthless in dealing this will be able to reopen their economies quickly, reopen borders with other sane countries. Economically they will recover very quickly.
Countries like the US which have no unified and sane policy are going to take a full decade to recover. Some parts will never recover.
It's likely going to be the opposite as recent tests in Korea seem to show immunity does happen. The countries that did little to stop the spread will have or be close to immune while the countries that aggressively locked down will not be able to interact with most of the world.
No country has got anywhere near 50% of infections. There seems no appetite currently for 4,000 deaths per million people that reaching herd immunity levels would require, at least in the western economies.
Deniers keep assuming that everyone will haplessly let themselves get infected. And the pandemic will be over in a couple of weeks. That is an incredibly stupid thing to believe.
Consider. Lets say that because people are terrified of the virus they protect themselves. Which to their credit most people are. And the growth rate drops from 35% to 5% a week. So how long does it take to get from 2% infected to 60%? Do the math and you find out it's 70 weeks or 18 months.
Sure, if you define “worst at handling covid” as “had a relatively small overreaction”. Sweden is looking great now (look at actual total mortality numbers, not the pessimistic “projections” they keep changing). No substantial QALY loss from covid, and substantially less economic devastation, stress, and depression compared to those countries that overreacted.
You have to be on a different planet to define Sweden's mortality numbers to be "great". They are 5-10x worse than the other Nordics, have one of the highest death rates in the world, and it's not obvious that they will have a long-run advantage despite all the propagandizing for it.
Their approach is highly experimental, which makes it all the more bizarre that they aren't testing very much. They have a "developing world" or "overwhelmed country" cases:deaths ratio (about 1:8) which suggests that they have a huge number of cases they don't know about. It's not clear why a country taking a radically experimental approach to COVID-19 would also test so lightly - it suggests that they don't want to know what's going on.
It's possible that they don't want to have embarrassingly high case numbers, but it's just as possible that their numbers are embarrassing in the other direction - i.e. while they've killed a huge bunch of oldies, they also haven't got nearly enough cases to have herd immunity.
We will also get to see, long term, what the morbidity effects of taking this approach are. They will not look super-intelligent if there is any kind of effective treatment or vaccine developed in the next 6-12 months.
They only look good when you compare them with hard-hit countries. The difference is that Belgians and Spaniards aren't patrolling every goddamn social media site announcing how well they've done with the virus.
I think they are doing a decent job of getting a death rate (compared to some other countries, e.g. the UK). But the implied case rate from the death rate implies that they are nowhere near herd immunity, which is awkward for them - if you've got 400K people infected (1:200?) you're still nowhere near herd immunity, yet you've killed tons of your citizens.
UK publishes weekly statistics of total deaths, including those mentioning covid on the death certificate and the number of excess deaths above the 5 year average for that week. The figures are a few weeks behind though.
This gives a number of covid deaths at 40-80k, and thus an infection of 3-15 million depending on the actual fatality rate.
That means letting it run free, assuming immunity once you have it, and a 65% herd immunity level, would mean at least another 100k deaths and possibly as high as 1 million. Most likely 250k more. There is no appetite in the UK currently for that.
We'll reopen our borders, probably soon (they're already open to legal residents), but until there's a vaccine we will have 2 weeks quarantine for all incoming travelers
We've had single digit new cases for almost 2 weeks now, 2 new cases in the past 3 days, none in my region for over 2 weeks, there are ~150 active cases nationwide, dropping every day. The goal is for all new cases to be occurring in quarantine.
but not likely. The pressure to develop a vaccine - or at least a very effective therapy like using monoclonal antibodies - is extremely high. Most people survive COVID19, so there must be either a way to trigger a proper immune response or to at least rebuild parts of their response.
We‘re currently doing a lot of very advanced science in all related fields in parallel and I think that we can be very sure that we‘ll come up with multiple useful solutions within two years or so.
And with a lot of general advancements to scale out processes that have been done on small scales until now.
That does not mean that we‘ll be back to what used to be “normal“, though.
That would be insane. They probably mean until they figure out how to reopen borders and with whom without risking too much. And given how many countries are doing the same thing maybe even an international agreement of some sort will emerge where only people from virus-free countries or recently tested people will be allowed to take flights.
The disease is close to eradicated inside the borders of NZ. At this point there are only a couple of hundred active cases and we’ve now had a couple of days with 0 new cases. Australia seems to be on track for the same thing.
Not unless they are going to send people home if they are positive or forcibly quarantine them and perform contact tracing and further testing. Thus far most western governments have strongly resisted enacting such measures.
You can't safely open up without employing either highly accurate testing + rapid testing + forced quarantine + contact tracing, or having your population immunized. It's pretty much that simple.
See .. you're speculating on what they mean. Wouldn't it be nice if they provided a bit more information so we wouldn't have to parse out meaning out of ambiguous statements? You know, they could provide some details on what needs to happen to re-open. Are we waiting for a vaccine as a precondition for reopening? Or herd immunity? Or case count to drop below X?
Auckland looks less concerning than places like London or New York. I have confidence that the NZ government will deal with it far better than uk or us
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.
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.
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.
> 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.
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.
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.
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.
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
> 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.
> 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.
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.
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.
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.
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 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.
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.
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.
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.
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.
*I put "essential" in quotes here because I believe the definition of essential changes the longer services are closed. For instance, a dentist isn't really essential when they're closed for a month, but a 3 month closure is going to be increasingly problematic for people needing something more than a standard cleaning.