Florida is really thinking outside the box. Schools will have no problem opening up if children have herd immunity. This is the type of creative thinking school administrators have been looking for.
Why would any country want herd immunity from infection when nearly every developed country has demonstrated the virus can be contained without such a large loss of life? It's not as if the specter of maxed out hospitals on the news for months on end is going to help the economy.
>the virus can be contained without such a large loss of life?
Generally speaking:
But then you have to keep containing it right?
There's not a magical end of containing unless the virus just goes away / a vaccine is available ... that doesn't seem to be a thing yet.
I'm not all for just letting the chips fall where they may, but success at preventing exposure to your population vs heard immunity means the folks who haven't been exposed have to keep avoiding it.
If you don't have herd immunity, then you need to be continually surveilling for it, and when it's present, switch to containment.
Containment is easier when the number of cases is small though. If you get a handful of cases, contact trace and make general advisory news releases. If you get more than 20 cases, ask people to wear masks. If it gets worse, then you have to take bigger steps.
A lot of assumptions here. Immunity may not even be long lasting. I live in a country where we've largely stopped community transmission, and now we can open back up with masks for all to keep it that way until we all get vaccinated next year.
America's strategy (or lack thereof) is simply negligence.
Please stop repeating the “there might not be long term immunity” meme. It is unfounded and contradicts decades of established immunological principles.
Memory T-Cell reactivity to SARS-1 has been shown to persist across decades. The latest study showed strong activity after 17+ years.
SARS-2 is incredibly structurally similar to SARS-1.
Even if we pretend t-cells don’t exist, immunological memory is a thing. Once circulating antibodies have completely faded after months, there still remain memory b cells which persist across decades and will ramp up antibody production all over again when exposed to SARS-CoV-2. Therefore the subsequent infection is addressed more quickly and more powerfully, leading to lower peak viral load and therefore theoretically lowered transmissibility and vastly improved individual outcomes.
So if we pretend half the immune system doesn’t exist, then you can get reinfected months later but you will spread way less and not be at any significant personal risk of bad outcome.
Herd immunity works. It’s a natural phenomenon that has been unjustifiably demonized.
If herd immunity works, then what is your explanation for the fact that alpha and beta coronaviruses such as 229E, NL63, OC43, and HKU1 (responsible for many occurrences of the common cold) are in continuous circulation?
I never said anything about herd immunity, all I've said is that immunity may not be long lasting.
Basing an entire countries policies around a supposition that herd immunity is practical is, in my opinion, negligence. It's only practical for diseases that don't kill 0.5-1% of the infected population.
It's been proven that lockdowns and slow reopenings work to limit spread, followed by contact tracing clusters to prevent reemergence until community vaccination programs.
Americans are just bitter that their governments are totally inept.
No, it's a matter of assessing risk. Why would you risk infecting your entire population with a novel virus that kills on the order of 1% of all infected, when you can do shutdowns and perform slow reopenings to limit spread below 5% of the population until vaccination?
We should be assuming that immunity doens't last long and basing all policies on that assumption until proven otherwise.
I know it certainly appears like a suboptimal strategy, but it assumes that the measures did indeed do what they were expected, that's contentious (we can discuss why, but I think it's obvious).
In a risk-benefit analysis, it leaves future (speculative) advances in treatment VS acquiring herd immunity as quickly as possible and with minimal actual damage, for this it makes sense to maximize exposure for the less at risk.
Also, the summer is a better season to get infected, at least because of generally better immune system function (because of better vitamin d status).
Not just Vitamin D, but to a lesser extent nitric oxide as well.
Anyway to state your excellent point in a different way: “contain until vaccine” is a strategy based around a temporally unbounded future event. When has it ever made sense to bet the farm on a highly uncertain future event?
This world would be so much better off if we never knew that SARS-2 existed and therefore did not engage in any artificial suppression of natural transmission.
Hospitals/ICUs being overrun in the United States is not realistic. I'm not equipped to discuss the medical capacity of other countries, but Sweden did fine.
Exactly. Absent a vaccine, herd immunity is the failure condition that occurs when a virus has infected as many people as it can within a population. It is the default baseline against which all interventions should be compared.
If immunity to the disease is not long-lasting (> 3 months), herd immunity is likely impossible. There are plenty of viruses that can reinfect people who have recovered from them (Coronaviruses being a common example of these) for which we have no herd immunity.
Is there any evidence you can re-contract Covid-19? If not, I'd fall back to the following argument: Some health care workers have been exposed regularly for six months by now. It'd be very news worthy if someone was confirmed to be re-infected. Given I haven't seen that news, I think I can conclude that immunity lasts at least six months in working age people.
Also, if I understand correctly, it has recently been shown that people who were infected with SARS 17 years ago still have memory T cells for SARS. (And, I think SARS is one of the viruses most closely related to Covid-19, and therefore there's reason to expect a long immunity period for it too).
"Memory T cells induced by previous pathogens can shape the susceptibility to, and clinical severity of, subsequent infections. <snip> We then showed that SARS-recovered patients (n=23) still possess long-lasting memory T cells reactive to SARS-NP 17 years after the 2003 outbreak." - from https://www.nature.com/articles/s41586-020-2550-z
Immunity isn't a binary, neither is herd immunity. While there are reports of reinfection, those cases are quite rare.
Even a modest degree of immunity can significantly lower spread. In France, Spain, Germany, you still have hundreds of cases every day, but they don't grow to thousands of cases anymore.
> While there are reports of reinfection, those cases are quite rare.
The disease hasn’t been around long enough to make this claim.
> Even a modest degree of immunity can significantly lower spread. In France, Spain, Germany, you still have hundreds of cases every day, but they don't grow to thousands of cases anymore.
This is true, but depends on the duration of immunity and a more uniform global response (or very tight border and quarantine adherence). Ongoing, sporadic COVID crises would still be pretty disruptive unless we have highly effective therapeutics.
Cases are low and falling in New York, Sweden, London, Italy, Spain, despite varying and loosening social distancing measures. How do you explain that? Those places already have herd immunity. Serotesting for antibodies misses t-cell immunity and other forms of resistance, and variation in spreading patterns makes the herd immunity threshold lower than we thought. This is the only plausible explanation and nobody wants to admit it.
Look, what you are saying makes sense until you say "This is the only plausible explanation" at which point I get lost. Just because you can't imagine other explanations doesn't mean that there aren't any. And this also presupposes that there are no hazards to anyone in that case. The fact is this disease remains very dangerous for a lot of people. So while it's plausible that we will have herd immunity sooner rather than later, it also misses the point which is that it's very dangerous to get infected with this virus.
No, they don't, or they wouldn't have new cases, even without even somewhat looser mandatory controls than other places. What they have is some degree of immunity in the population (not herd immunity) plus (in some subset of those places) some degree of contact tracing backed by targeted mandatory, or at least voluntary, quarantines/isolation of the exposed, and (in large part because of the intense impacts each has had) voluntary general distancing.
> No, they don't, or they wouldn't have new cases, even without even somewhat looser mandatory controls than other places.
That's not what herd immunity means.
The Herd immunity threshold is attained when the R factor drops below 1, assuming otherwise uninhibited spread. The threshold for herd immunity for COVID-19 has been estimated at 50-80%, but that is assuming an R0 that is likely overestimated.
Given that spread is still mitigated by certain interventions, and since we don't know the impact of those interventions on R, nor do we know R0, we don't know if we have herd immunity. However, we do have R below one in many European countries.
Herd immunity isn't a binary threshold after which zero cases occur. Even in a first-order homogeneous and well-mixed SIR model, you may asymptotically approach 1 - 1/R0 of the population infected without ever getting there. If you do cross that threshold ("overshoot"), then the case count starts to drop, but new people still get infected and die on the downslope. The only case where a disease will naturally burn itself out abruptly is if there was massive overshoot, which would be bad, because it means yet more people died than necessary for natural herd immunity.
And for real some people have many more contacts than others (nurses, police, etc.). They get infected first, with disproportionate harm, but then become immune first with disproportionate benefit. That heterogeneity means 1 - 1/R0 is potentially a significant overestimate of the share of the population that needs to get infected for herd immunity, but there have been very limited efforts to quantify that so far.
It seems like some people believe natural herd immunity (from recovered patients) could work like vaccination does, to effectively eradicate the disease? That's probably false--the most likely natural endgame would be that the coronavirus becomes endemic, always present with some low incidence, with continuing mortality that's very low (because the incidence is low, and because older people probably benefit from immunity from when they were younger and the IFR for young people is <1/100 of older people's) but nonzero.
Finally, herd immunity and interventions (social distancing, masks, etc.) work together. It's possible (and likely I believe) that in hard-hit areas that now show R ~ 1, this is due to the product of both factors, and that either relaxing to their previous lifestyle or applying the same interventions in a naive (100% susceptible) population would show R > 1.
Cases are lower still or zero in many other places with far too few cases to have achieved herd immunity. The only plausible explanation is that containment measures have some effect.
Every increase in the percentage of people with immunity reduces R0. At some point, even absent any other measures, the R0 would be below 1 just due to the number of people that are immune; herd immunity.
But in any case, the immunity level of the population reduces the need for other measures in order to stay below an R0 of 1.
There’s a massive spectrum of efficacy in the dozens of different suppression or containment policies that can be applied, combined with demographics and geography of the location being studied.
But in any case, the immunity level of the population is a downward force on R0 that, for example, will naturally keep daily cases lower in New York vs. Florida regardless of policy.
The problem with this plan is that it's very hard to do safely. Let's say I don't care about deaths from COVID-19 that were untreatable; I still care about excess deaths tyat were treatable, but don't get treated because hospitals are overwelmed by patients or overwelmed because medical staff is sick.
To avoid that, you basically have to limit the number of beds COVID patients are using and modulate the infection rate to keep the beds in use close to the limit without going over. Of course, modulating the rate is difficult, because people's behavior is hard to modulate. Also the demand for new beds shows up about 2 weeks after infection, so you have to modulate today based on what your bed capacity looks like then.
Hospital are frequently overwhelmed in the past, nothing new, at least at current situation is no more overwhelmed than what has frequently happen in the past.
And worth noting that there is not a whole lot hospitals can do anyway. The overwhelming majority have COVID-19 that is so mild that they never would go to a hospital. Of those that have more serious symptoms, some will be benefit from being given oxygen. There are very few people who warrant invasive ventilation, and those that do have very bad odds anyway.
The meme around hospital overrun is just that, a meme. Especially given everywhere having at least a small percentage of positive serology tests. I doubt anywhere in the US would get truly overrun with uninhibited spread at this point.
Vaccines can either reduce the severity of disease or grant immunity for a period roughly comparable to the window of reinfection. Depending on the duration of immunity, a successful vaccine may require multiple doses per year.
Vaccination is likely an option for long term COVID-19 herd immunity. The mutation rate is shockingly low, so a nationwide focus on containment was the best option early on. It’s still possible without wrecking the economy.
The US seems to be using the worst off all possible options. However, several countries have succeeded and demonstrate it’s possible to succeed.
Assuming we capture about 10% of COVID instances as actual cases, then the US is getting 770,000 new instances a day.
Stockholm burnt itself out with 20% of the population getting immunity (determined via antibody testing).
So (328,000,000 - 37,000,000) / 770,000 = 378 days until herd immunity, considering the existing cases.
What is more likely is that the case numbers will ramp up significantly though, to over 100,000 per day at some point. In that case the USA will have herd immunity within the year.
This is nothing new. Influenza hits about 20% of the population (60 million people) as well and then burns out for the season. We struggle yearly with keeping influenza out of nursing homes and with the surge of hospitalization that it creates.
The good news is that right now there are no excess deaths in the USA and that hospitals all over the country are handling the virus and not running out of space (more beds can be always be converted to ICU, ICU capacity is not infexible, same as is done for influenza).
There are already hospitals in Texas and I think Florida that are rejecting patients because they are full, that's when fatality rate and excess mortality kicks in. What kills you isn't suboptimal care, it's the impossibility of getting any treatment.
Capturing 10% of cases would put the US CFR of ~0.4% which is completely unsupported. Increasing that to even 30% so a 1.2% CFR and your talking 3.1 years which is well past estimates for an effective vaccine.
PS: Influenza vaccines are common with 68% of people over 65 getting vaccinated in the US. Further at least half of all cases are asymptotic which ends up contributing significantly to herd immunity.
20% of 328 million is 65.6 million. Divided by 770k is ~85 days.
It’s probably better to think of immunity as regional and also not binary (herd vs not herd).
States like MA and NY have a significant benefit from their population immunity levels, versus FL and TX less so. That is to say they have to do less (if not nothing) to keep their R0 below 1 and whatever cases do show up are less likely to spread widely.
Immunity benefits are cumulative to any policy measures put in place. You can try to slow down the rate (flatten the curve) which might not change the ultimate case count in the end, but can lower deaths through greater availability of care. At some point immunity and mitigation measures combined will get you below R0 of 1.
If you’re an island nation with enough testing for effective contact tracing and constant vigilance and willing to lockdown repeatedly, then the other option is trying to actually prevent any spread even without any immunity, but you have to be able to continue this process indefinitely until a vaccine is widely available.
I would make of it that these are outliers cherrypicked for the scare value in the headlines. The vast majority of hospitals everywhere are doing fine.
In New York, the hospitals are so far under capacity that they're running TV ads begging people to start coming back in for elective procedures.
Cases are surging in Florida and Texas, not New York. New York's wave is past. When New York's wave was at its peak, hospitals and doctors there were absolutely maxed out. There were first hand reports from doctors and nurses on the front line who said as much. If they had not undergone a complete lock down things would have been much worse.
Now we see new waves popping up elsewhere and surprise, their hospitals are filling. Hospitals are having a great time in places where they took the virus seriously. New York did not take it seriously at first and they suffered. Now Texas and Florida are not taking it seriously and they are suffering as well. And you're suggesting that we can just let the virus run rampant and we won't see our healthcare system buckle?
> In New York, the hospitals are so far under capacity
Do you think 20% exposure (at a cost of 17.5k lives) buys you herd immunity?
Even in hotspots like New York City that have been hit hardest by the pandemic, initial studies suggest that perhaps 15-21%6,7 of people have been exposed so far. In getting to that level of exposure, more than 17,500 of the 8.4 million people in New York City (about 1 in every 500 New Yorkers) have died [...]
To reach herd immunity for COVID-19, likely 70% or more of the population would need to be immune.
https://coronavirus.jhu.edu/from-our-experts/early-herd-immu...
> The vast majority of hospitals everywhere are doing fine.
That's great if you need something done at a hospital that is not super time sensitive; it's not great if you're in the area where hospitals are overful and you have an urgent need.
Epidemic response needs to be done at a regional level in response to what's going on in that region, taking note of what's happening nearby as it might spill over, and learning from other areas within the country and worldwide to try to figure out what works best. It's totally reasonable, if the numbers support it, for some regions to be increasing restrictions and others to be decreasing restrictions. Clear communication from all levels of response would certainly help.
> Vaccination is likely an option for long term COVID-19 herd immunity.
To achieve herd immunity for measles at least 90-95% of the population need to be vaccinated. A disease like polio is less contagious, and 80-85% of the population would need to be vaccinated for herd immunity to work.
https://www.ovg.ox.ac.uk/news/herd-immunity-how-does-it-work
It suggests our immunity to SARS-CoV-2 does not last very long at all — as little as two months for some people. If this is the case, it means a potential vaccine might require regular boosters, and herd immunity might not be viable at all.
https://www.medrxiv.org/content/10.1101/2020.07.09.20148429v...
Can't get 80% people to wear a mask, much less seasonal vaccinations.
I'd be guessing that very early in the quest towards herd immunity the medical institutions would be overrun and the end result of that would be a whole lot more dead people than the lockdown scenario.
From what it appears we know about the virus so far, a vaccine is the only sane way to possibly hope to reach herd immunity.
Protect the vulnerable (no sending Covid positive patients into their living spaces!) while allowing low risk population to develop and overcome the virus.
This seems like the most logical way to combat issue, as opposed to hiding and hoping it goes away. Of course proposing it publicly means to be smeared by the media and politicians and twitter blue checks, who always have our best interests in mind.
Does this solution cause no pain and death? Of course not! It’s about causing the least amount of pain long term, including the externalities of our actions.
The problem is that this is incredibly hard to do. It’s much easier to protect the vulnerable if the routes for community transmission are reduced or eliminated; if society is acting as normal it’s really hard to stop those specific transmission vectors. Given that we can’t convince people to wear masks, I’m dubious about any plan that requires more planning and communication.
We also have no idea if herd immunity will work, or for how long. Lots of coronaviruses confer either no immunity or a short term one; remember that a lot of common cold cases are coronaviruses too, and you can catch those repeatedly. Also, pursuing herd immunity involves infecting basically 20-50% of the population, a strategy that might kill 500k to 1.5mil Americans (assuming CFR stays at 1%, an optimistic assumption in this scenario)
We also have no idea what the health impacts for non-fatal cases are. Lots of patients are surviving with heart & lung damage; long term impacts TBD. Crippling an entire generation from the get go would both be tragic, and would put lie to the idea that not opening schools is “letting them fall behind”.
There isn't enough evidence of long term immunity to make herd immunity a sensible strategy. It's smeared by the media b/c it's way less preferable than the alternative of containing it like nearly every developed country in the world.
“This strategy would kill over half a million Americans” isn’t even really a smear, it’s an accurate description of why the herd immunity strategy is bad.
They said the same about tens of thousands dying; we’re now at 141k dead Americans. If you want to dismiss it as “fear mongering” that’s your prerogative, just don’t be surprised that most people find this unconvincing.
The problem with this approach is it also assumes that overcoming the virus means a return to 100% health with no long term impact. We're already seeing that it can lead to other long term conditions. I have a friend who is being treated for heart damage after having COVID.
I'm in a low risk population but just because I'm not likely to die from it doesn't mean it's completely harmless to me.
Protecting the vulnerable has never actually worked. In theory it's possible, but it would require constantly testing nursing home workers that don't have the money to do this and an administration that hasn't shown the ability to support it. Every area that's had a significant level of spread has had issues where nursing home care workers brought in the virus from the community. The exception is Hong Kong where nursing home residents were quarantined in hospitals for significant periods. This presupposes the leadership to setup a system like this and the willingness of nursing home residents to be isolated for long periods of time. If we had either of those things we'd be able to contain the virus in the broader population.
That's not how it works. If you had 100% immunity in the young, the old would still be at relatively similar risk because of homophily in social networks. That is, old people spend most of their time with old people. Herd immunity for the general population requires a homogenous mixture of social interactions across those infected.
Keeping the vulnerable protected sounds good and all, but in the case of, say, children, the vulnerable is the teaching staff.
The alternative - hiding people in homes until vaccine is widely available - means death.
From alcohol & substance abuse, from increased suicides, from domestic violence, and so on. Extended period of being prevented from running your business (or out of employment) without steady income, and bottled up at home is a major stresor and silent killer. The hospitals already reported significantly elevated suicides.
There is no magical strategy to stave off all the problems; balancing the risks and managing precautions as our knowledge expands is the correct, if hard to politically sell, way to go.
Opening up without restrictions would kill somewhere between 500,000 and 1,300,000 Americans, assuming that the CFR doesn’t rise above 1% (an optimistic assumption). If you think lockdowns will kill that many Americans, then provide your sources.
The new estimates of HIT factoring in widespread t-cell cross-reactivity in humans that have NEVER been exposed to a SARS-like virus nor anyone who was themselves infected with one, implies that the true HIT is somewhere around 25%.
Do the math on the US with an IFR of .3% and an HIT of 25%. That’s what a likely scenario looks like. It means a few hundred thousand dead.
As an upper bound do the same math with .9% IFR and 25% HIT.
BTW you should also consider the risk that lockdown puts the body into a state where it is more susceptible to bad COVID-19 outcomes, due to vitamin d deficiency, lack of nitric oxide, lack of exercise, reduced sleep, social isolation, unemployment, and an unprecedented environment of widespread fear&hysteria. Also consider the lives we have already lost when calculating the delta between containment versus not practicing containment.
IMO containment is a foolish and infantile strategy which makes us perpetually at risk of an outbreak. Population immunity is the stable and logical solution. Banking on a vaccine is an awful idea, doubly so in a country where we can’t mandate a vaccine without plunging ourselves into civil war. Vaccine-attributable herd immunity only works if a bunch of people get vaccinated. Granted the t-cell reactivity findings alter the calculus there, but we would need to vaccinate people who do not demonstrate cross reactivity in order for that fact to change the number of required vaccines.
Or...what could have been done from the beginning. 3-week lockdown to get a grip, then mandatory mask laws (indoor and outdoor) and a reduction in indoor events and large social gatherings. Life and the economy goes on mostly as normal.
Even in the SF Bay Area, fewer than half the people I see outside actually wear masks. It's crazy how little people seem to care.
stop worrying about, and projecting unfounded motivations upon, maskless people outside. it's better for your health via stress reduction, at the very least.
I know you're joking, but I was surprised to learn [1] that there are cases pointing to the likelihood that recovery from infection will not necessarily lead to immunity from subsequent infection.
The Health Ministry of Switzerland has said children cannot transmit covid at all. Along with the fact that children being affected by the virus is extremely rare, it would seem like the only concern is for adult staff to maintain precautions with each other, which seems much safer than e.g. working in a close quarters kitchen line, which we've been allowing all along.
People getting herd immunity involves people, you know, actually contracting the disease.