
Population-level herd immunity against Covid-19 will not be achieved in 2020 - arunbahl
https://coronavirus.jhu.edu/from-our-experts/early-herd-immunity-against-covid-19-a-dangerous-misconception
======
somewhereoutth
Herd Immunity would seem a dangerous strategy or objective bearing in mind the
following:

\- Immunity may only last a short time, in common with other Coronaviruses.
Re-infection may be less severe, more severe, or not possible. We don't know.

\- Infection Fatality Rate is uncertain, but could be as high as 1%.

\- Long term health effects are unknown, but for example some evidence
suggests permanent lung damage is possible.

Significant areas of the globe have successfully suppressed the virus, and may
even be looking towards eradication. Such countries are looking to establish
'travel bubbles' or 'green zones' between them and get back to normal (within
their virus free spheres).

For other areas, it may be too late for suppression, or for societal reasons
suppression may never have been practicable, in which case herd immunity as an
idea could be considered a palliative.

~~~
nabla9
> Immunity may only last a short time, in common with other Coronaviruses

Where you get this information? I seem to recall exact opposite. Coronaviruses
mutate slowly and immune responses last several years. For four seasonal
coronaviruses the immunity lasts 1-2 years, longer than other viruses causing
influenza.

~~~
svd4anything
[http://www.columbia.edu/~jls106/galanti_shaman_ms_supp.pdf](http://www.columbia.edu/~jls106/galanti_shaman_ms_supp.pdf)

------
gshdg
We still don’t even know whether immunity to this lasts more than a few months
(as is common with other coronaviruses). So it’s premature to talk about herd
immunity regardless.

~~~
Gwypaas
SARS, another corona virus immunity lasts for 3-4 years on average with some
cases up to 11 years. So it wouldn't be surprising at all with at least 1-3
years of immunity for people who had more serious infections.

~~~
Simon_says
How could this possibly be known? The first case was in 2002, and the last
case was in 2004.

~~~
Gwypaas
Because you can study the response without having the disease in the wild.

[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7115611/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7115611/)

~~~
Simon_says
That's a nice article. Thanks for responding. The 3-4 year timeframe you
mention isn't in there. Is there another source for that?

~~~
Gwypaas
I've seen it mentioned with sources on /r/COVID19 a bunch of times.

I think this is the study they might have been referring to? And this is
antibodies, not the memory cells mentioned above.

[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851497/](https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2851497/)

------
alpineidyll3
It's interesting to compare how the world reacted to AIDS which is still a
pandemic.

Before the hiv was understood in detail, policy responses were blunt or non-
existent. Many kids including myself were taught to abstain from sex entirely,
which of course is a policy which would work on paper but with which no one
can comply in practice.

Here in Texas our lockdown has has little effect on the viruses rate of
transmission. I believe that's because like many southern states, we could
never achieve good compliance.

More realistic policies which take into account the fact that young people are
at far less risk for the virus will likely win the day. We can better support
and sustain quarantine if it's triaged for those at greatest risk.

Instead it Looks like policymakers will just let go of trying to control this
in the US, and many older people will die unnecessarily.

~~~
gwd
> Here in Texas our lockdown has has little effect on the viruses rate of
> transmission.

What makes you say that? (Genuine question, not a challenge.) This website
shows the estimated Rt going from a peak of 2.08 down to below 1, before
stabilizing at 1.06:

[https://www.covidactnow.org/us/tx](https://www.covidactnow.org/us/tx)

1.06 is still > 1 which is bad, but it's certainly a lot better than 2.

EDIT: Rt, not R0

~~~
alpineidyll3
Well, I was eyeballin' off a log-log plot, which is admittedly much less
precise than your link. Even on that plot though R dips before we even
officially shut down (Texas' cases were probably mostly imported from LA and
elsewhere, and cut down by travel ending before we had an order in place)

I'm also concerned that the law currently is at variance with the reality that
the parks are full here in Austin. Instead of rushing to be open, I wish the
government would tailor it's message to people who need it, and come up with
'clean' food/resource pathways for people who are vulnerable to this virus
rather than trying to keep kids out of the water.

------
StavrosK
Why would it? Everyone is trying to avoid getting infected (and dying). Isn't
that what we should do?

Herd immunity means "it's killed as many people as it could".

~~~
stargazer-3
No, herd immunity means "enough people are resistant so the vulnerable ones
don't get infection spread to them at all". There's a big difference there.

~~~
sp332
How would you be resistant without getting infected? There's no vaccine.

~~~
dragonwriter
You wouldn't be, you'd just be relatively unlikely to be infected since most
people around you would be immune and the virus would have difficulty getting
to you.

But the degree and duration of immunity that usually follows SARS-nCoV-2
infection isn't well established yet, and coronaviruses in general are noted
for not producing lasting immunity.

~~~
sp332
Yeah that's what I'm asking. By the time you get to "herd immunity", most of
the population has already been infected. To get most people to be resistant,
most people need to get sick first!

------
taneq
Anyone could have told you that. Or rather, anyone could have told you that
_if we make some attempt at 'slowing the curve' in order to try and keep the
number of ICU-requiring cases below the number of available ICU beds_ then it
will take years if not decades to achieve herd immunity.

You could just go for broke, let everyone catch it at once, and RIP 5-10% of
your population. Even then it'll take most of a year to run its course and
that year will be much, MUCH worse than just not being able to go to the pub
or get a manicure.

~~~
ravenstine
People are dying in their homes both from not going to the hospital and from
suicide. This isn't just about whether people are killed by one particular
virus.

~~~
TheOtherHobbes
Those numbers are tiny compared to the virus deaths, and even more tiny
compared to the death rate if the virus was simply allowed to cull as many
people as possible.

~~~
guscost
CDC is estimating that a little less than 40% of the excess deaths in the past
few weeks were not caused by COVID-19:
[https://www.cdc.gov/nchs/nvss/vsrr/covid19/excess_deaths.htm](https://www.cdc.gov/nchs/nvss/vsrr/covid19/excess_deaths.htm)

~~~
tsbinz
That is not what I get from this page.

> These deaths could represent misclassified COVID-19 deaths, or potentially
> could be indirectly related to COVID-19 (e.g., deaths from other causes
> occurring in the context of health care shortages or overburdened health
> care systems).

That is not saying "those deaths were not caused by COVID-19". They explicitly
mention that these could be misclassified.

~~~
guscost
Nice catch, thanks. Most of them are not, you'll find out:

[https://www.washingtonpost.com/health/patients-with-heart-
at...](https://www.washingtonpost.com/health/patients-with-heart-attacks-
strokes-and-even-appendicitis-vanish-from-
hospitals/2020/04/19/9ca3ef24-7eb4-11ea-9040-68981f488eed_story.html)

[https://boston.cbslocal.com/2020/05/04/coronavirus-
covid-19-...](https://boston.cbslocal.com/2020/05/04/coronavirus-
covid-19-massachusetts-fatal-crashes-rate-doubled-april-massdot/)

[https://www.nydailynews.com/coronavirus/ny-coronavirus-
queen...](https://www.nydailynews.com/coronavirus/ny-coronavirus-queens-
suicide-rates-increase-20200429-mqyzdplseva5belmqewn43u56i-story.html)

------
apatters
The epidemiologists at JHU certainly understand this stuff better than I do,
but a couple things about this article stood out to me. Is there an
epidemiologist out there who could comment?

\- The herd immunity threshold depends on the reproduction number of the
disease (R0). There's a basic reproduction number which is the rate they
expect based on properties of the virus, and an effective reproduction number
which is what ends up happening in reality. When effective R<1 the virus
starts to die out.

\- The basic number can't be changed but the effective number can be changed
dramatically. Lockdowns and social distancing have already changed it, with
varying levels of success in different locations.

\- I have seen numbers thrown around that peg the herd immunity threshold for
COVID-19 at 50-70%. This number is actually influenced by R, the lower R is,
the lower your herd immunity threshold goes. JHU uses 70% here and that's the
most pessimistic estimate I have seen.

\- Wouldn't good, sustained social distancing lower effective R and thus
produce a herd immunity threshold lower than 70%, perhaps much lower?

\- New York is at 15-20% exposure already.

I read this article from the Oxford Centre for Evidence-Based Medicine a while
back which observed that the early estimates for epidemics and pandemics are
invariably worse than what ends up happening in reality, and it got me
thinking. [https://www.cebm.net/covid-19/global-covid-19-case-
fatality-...](https://www.cebm.net/covid-19/global-covid-19-case-fatality-
rates/)

My personal bias is that I don't believe it is even possible, let alone wise,
to keep people locked down on the time scales that are needed for controlling
this virus, so they just kick the can down the road. But unprecedented levels
of social distancing _might_ be possible if we are smart enough. Every single
person who works from home, wears a mask, or keeps their distance in public is
helping.

------
eiji
With this mindset and approach the US will continue to have 20 million +
unemployed all the way through Christmas.

~~~
alistairSH
What mindset? That preserving life is more palatable than making money? I'm ok
with that. I'd rather be unemployed than dead.

~~~
makomk
If unemployment is better than death, why stop at doing this for Covid-19? For
example, the flu kills quite a lot of people each year, and even though
Covid-19 is somewhat more deadly that's counterbalanced by the fact that
stronger, longer measures are required to stop it. Why not shut down parts of
the economy every flu season?

(I've generally seen this kind of not one life argument go hand in hand with
the idea that Covid-19 cannot be compared to any other cause of death, for
obvious reasons.)

~~~
steveeq1
Don't know why this is being downvoted. The flu kills tens of thousands a
year, yet no one seemed to want to shut down the economy in the past. . .

~~~
alistairSH
10s of thousands vs 100s of thousands (or millions). Between higher mortality
rate and higher level of transmission, C19 is FAR more deadly than seasonal
flu.

The flu is a recurring problem. We can't avoid it.

COVID is (hopefully) a once-in-a-lifetime occurrence (just as the 1918 flu
was).

~~~
steveeq1
But death still occurs with the flu! Doesn't this mean you don't think life is
more palateable than making money?

~~~
throwphoton
The same philosophical discussion can happen with respect to raising the speed
limit by 5 miles per hour; it will result in more deaths... is it worth it?

But letting Covid-19 run unchecked is more akin to raising the speed limit by
50 miles per hour. The prudent choice is not to go with it.

~~~
steveeq1
But quarantining after the flu can "save lives". But my point is that it runs
counter to the "That preserving life is more palatable than making money"
argument. It's a tradeoff, in other words. If you REALLY wanted to "save
lives", you can quarantine during every flu epidemic.

------
guscost
> 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.

That's people with antibodies, not necessarily everyone who was exposed. There
is zero information on seroconversion rates for mild and asymptomatic cases.
We need to PCR-test a huge random sample, then follow up later with a
serosurvey. Why are we not studying this? And why does nobody ever write a
disclaimer listing their assumptions when making authoritative proclamations
like this? It's going to shred their credibility into dust by the time this is
all over, even if half of their assumptions turn out to be correct.

Another study suggests that 20% infected could be enough for herd immunity, if
individual variation in susceptibility is similar to the estimate for SARS-
CoV-1:
[https://www.medrxiv.org/content/10.1101/2020.04.27.20081893v...](https://www.medrxiv.org/content/10.1101/2020.04.27.20081893v1)

------
ravenstine
I'm trying to figure out if this article is actually saying anything or saying
effectively nothing.

> 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.

(goes on to mention how many people are dying)

> Some have entertained the idea of “controlled voluntary infection,”9 akin to
> the “chickenpox parties” of the 1980s. However, COVID-19 is 100 times more
> lethal than the chickenpox.

(goes on to completely dismiss whether that would actually lead to some level
of herd immunity)

I get that the disease is more deadly. But is this one of those cases where
it's better to pull hard and rip the band-aid off in one go? Nobody seems to
really want to broach this topic seriously.

> To reach herd immunity for COVID-19, likely 70% or more of the population
> would need to be immune. Without a vaccine, over 200 million Americans would
> have to get infected before we reach this threshold. Put another way, even
> if the current pace of the COVID-19 pandemic continues in the United States
> – with over 25,000 confirmed cases a day – it will be well into 2021 before
> we reach herd immunity. If current daily death rates continue, over half a
> million Americans would be dead from COVID-19 by that time.

It's unclear to me whether the author is stating that herd immunity would take
too long under the condition that we completely opened up the global economy
or if we all continued to stay isolated.

We're definitely not going to reach 70% with the way things are.

~~~
Michael_Murray
We have talked about “pull off the bandaid”- to have 200M people get the
disease means we’re going to lose somewhere between 1-2M people (just in the
US).

Doing that quickly means hospitals and morgues overflowing with dead from
COVID.

We HAVE talked about this from the beginning - this is the point of
“flattening the curve”. If we let a million Americans die in a short time,
it’ll tank the economy and overwhelm our healthcare system and ability to
treat not only this disease but all others at the same time.

It’d be one thing if we were testing and tracing to try and limit. But this
YOLO strategy is a recipe for complete chaos.

Even more inportantly: we don’t understand the long term impacts for those who
survive. What is the 5-year mortality rate from complications? The US DOD has
already decided that COVID infection disqualifies you for future military
service (ostensibly because of the lung complications, but they haven’t said
why formally yet).

The YOLO strategy that some folks are proposing is insane given how much we
don’t know about this disease. It would be like proposing in 1982 that we get
everyone infected with AIDS so we had “herd immunity”. Think about how that
would have worked out for us... and then tell me that it’s a good idea to do
it this time.

There may be a time when we know enough to make smart risk decisions about
this disease, but less than 6 months after emergence isn’t it.

~~~
DuskStar
> We have talked about “pull off the bandaid”- to have 200M people get the
> disease means we’re going to lose somewhere between 1-2M people (just in the
> US).

IF a few things are true:

1\. The population being infected matches the demographics of the US as a
whole. If the population is instead "healthy people under 60", IIRC the deaths
go from 1-2M to 10-20k.

2\. There is no way to infect someone deliberately in a way that reduces death
rates. Variolation [0] has worked in the past, and is a possibility here. If
it provides an additional factor of 10 safety benefit, you could now estimate
1-2k deaths, down from 1-2 million.

0:
[https://en.wikipedia.org/wiki/Variolation](https://en.wikipedia.org/wiki/Variolation)

------
goalieca
I think herd immunity is an interesting point. Sweden is not there yet but its
effective R value has already dropped below 1 a while back and it will
continue to drop as the susceptible population continues to shrink.

Then there’s approaches like shielding that are interesting that are being
discussed a lot.
[https://www.nature.com/articles/s41591-020-0895-3](https://www.nature.com/articles/s41591-020-0895-3)

There’s something to note about this virus infection fatality rate: we don’t
seem to have an agreed upon value for it and there is quite a window. It may
depend on locale, population health, age, etc. But the 1% for the diamond
princess is quite high and I think that number was cited for caution.

~~~
nodamage
> But the 1% for the diamond princess is quite high and I think that number
> was cited for caution.

Why? The Diamond Princess has had 14 fatalities out of 712 cases which implies
a fatality rate of 2%, with 8 unresolved cases still in the hospital that
could push it even higher.

~~~
goalieca
I came across this the other day on reddit. It is another cfr study with much
lower rates.
[https://reddit.com/r/COVID19/comments/g6nmtf/_/foatvgv/?cont...](https://reddit.com/r/COVID19/comments/g6nmtf/_/foatvgv/?context=1)

There’s other highly tested populations with lower CFRs and then there’s IFR
estimates based on serology and indirect estimates on CFR that slew much lower
than 1%

~~~
nodamage
> I came across this the other day on reddit. It is another cfr study with
> much lower rates.
> [https://reddit.com/r/COVID19/comments/g6nmtf/_/foatvgv/?cont...](https://reddit.com/r/COVID19/comments/g6nmtf/_/foatvgv/?cont..).

I would be careful about generalizing results from that particular study as
99.5% of the workers sampled were under the age of 70. If your sampled
population does not include the most vulnerable age groups then of course your
fatality rate will be lower than normal.

> There’s other highly tested populations with lower CFRs and then there’s IFR
> estimates based on serology and indirect estimates on CFR that slew much
> lower than 1%

I'm curious what you mean by "much lower"? Some of the antibody studies
published recently have found prevalence rates that were not much higher than
the false positive rates for the test, making confidence in their results
somewhat dubious. In studies where the prevalence has been higher (e.g. NYC,
Geneva), the IFR is trending towards 0.5-1%.

This meta-analysis was published yesterday which suggests an IFR of 0.75% (CI:
0.49-1.01%):
[https://www.medrxiv.org/content/10.1101/2020.05.03.20089854v...](https://www.medrxiv.org/content/10.1101/2020.05.03.20089854v1)

------
badestrand
In the article that section about the cruise ship talked about voluntary self-
infecting and how that would be risky (1-2% death rate).

What this completely ignores is that obviously only young and healthy people
would attend those "corona parties" and thus the CFR of the voluntaries would
rather be around 0%. And obviously those people wouldn't immediately go see
grandpa but instead self-isolate for three weeks.

I hate that so many are pretending that it's like russian roulette when in
reality the odds are so highly skewed.

------
josefresco
I would liked to have read their opinions on Sweden.

~~~
lucideer
Do you live in Sweden?

A lot of people seem to be using it as some example of a country who haven't
introduced lockdown measures, whereas in reality they are actually self-
isolating and social distancing, just like everyone else.

Worth noting also that Sweden has the 6th highest case fatality rate in Europe
(other Nordic countries are near the bottom of that list).

~~~
brutusmcforce
Yeah, I'm swedish and we are very much self-isolating. We didn't close
schools, our idiot state epidemiologist didn't think nursing staff should use
masks etc. so lots of elderly got infected. Stockholm infection numbers are
insane, and we are probably getting there up north soon too.

Lots of small businesses are defaulting. I'm trying to support my local
restaurant by eating lunch there every day.

All in all, it's a mess.

~~~
orblivion
Did they close bars and indoor dining?

~~~
brutusmcforce
Gatherings over 50 persons are prohibited, many bars and restaurants have went
bankrupt though so I guess it's self-regulating.

