Absent a highly effective vaccine or some other cure, only two policy questions are relevant: how quickly should we reach herd immunity and whom should we protect during that period? The answers are obvious. We should achieve herd immunity as quickly as is prudent, while protecting the vulnerable, including the elderly, sick, and frail. Let the young and healthy become infected in the natural course of their lives to help create a protective layer around the old and sick. The first step is reopening schools and businesses.
No one wants to become infected with the novel coronavirus. But those who do can know that their private cost confers a public benefit, moving us one step closer to herd immunity. The good news is that we might already be close to herd immunity.
This is from David R. Henderson and Charles L. Hooper, “Herd Immunity: Saving Lives and Saving the Economy at the Same Time,” Brief Analysis No. 138, Goodman Institute for Public Policy Research, July 20.
Read the whole thing: it’s only 2 pages long.
Charley and I finished the piece about 10 days ago. Would I write it somewhat differently today? I would. I found this post by EconLog co-blogger Scott Sumner, published 2 days ago, persuasive.
READER COMMENTS
Alan Goldhammer
Jul 24 2020 at 9:34pm
It should be noted that Professor Ioannidis whom you quote was a co-author of the widely panned serology study of Santa Clara County that a Stanford research group conducted several months ago. Even when they tried to correct it for the sample bias and faulty statistics there were still problems in the second pre-print.
the problem in the Henderson/Hooper analysis overlooks the key problem that has vexed the US from the beginning, overcrowding of hospitals. Yes, most of those hospitalized do recover (I’ll leave aside the inconvenient fact that a fair number of people have lingering symptoms that we don’t fully understand) but the burden on the system is immense. Look at ICU bed use in parts of Florida, Georgia, Mississippi, Louisiana and Texas. this was the rationale for the lockdown to begin with, not excess mortality among ALL age classes. I don’t see how the analysis solves this issue.
It’s fine to speak in platitudes of opening schools, that the young are healthy and we don’t need to worry about them. This is also a misreading of how the virus is transmitted. From the South Korean data, children under 10 likely do not transmit SARS-CoV-2 but those 10-19 transmit the virus readily. Given this, how will physical distancing be practiced in schools? Do the schools have ventilation systems that will mitigate viral spread? What type of protection will there be for teachers and administrative staff? What happens if teachers elect not to return if they are asked about their choice of in-class or distant teaching (this question is going out in many school districts right now)? What types of disinfection practices will be implemented on a daily basis (some schools that I am aware of have costed this out and it will be expensive)? How will an outbreak of COVID-19 in a school be handled?
SARS-CoV-2 is not a simplistic virus and despite the rapid knowledge of the virus and its relation to the immune system, there are still unknowns (I could go on but as always, you can find my thoughts HERE if interested). Herd immunity is fine in concept but achieving it without doing collateral damage is difficult to accomplish. Had we put in place a proper public health plan things would be a lot better. As it is, the current economic downturn is likely to be with us for some time to come.
Ray
Jul 25 2020 at 1:18am
Prof. Ioannidis and the team at Stanford’s studies have withstood immense scrutiny quite well. In fact, the IFR predicted by both their studies as well as those worldwide have been pretty much spot on.
His early advice to focus on the seroprevalence results like those his team led would have told us much about the true threat of the virus being far less than the terribly incorrect models told us.
If we could go back in time and follow the advice he and Jay Bhattacharya gave early on we’d have significantly less economic hardship and the same or better health outcomes.
robc
Jul 25 2020 at 10:09pm
What overcrowding of hospitals?
Sure, there has been some in some areas, but mostly we have had underutilized hospitals.
The curve was overflattened in most places early on. Shutdowns and etc should be timed to get us to herd immunity as fast as possible without overcrowding hospitals. If icu utilization is under 60%*, open up a little.
Most of the country should have closed slower. NY should have closed faster.
* No idea of the right number, but somewhere about that.
Rebes
Jul 24 2020 at 9:54pm
“Let the young and healthy become infected in the natural course of their lives to help create a protective layer around the old and sick.”
So, David, where do you fall in the spectrum – young and healthy OR old and sick?
If you are not old and sick, what have you done recently to expose yourself to the virus and confer a public benefit?
David Henderson
Jul 24 2020 at 11:11pm
You wrote:
Neither: I’m old and healthy.
You asked:
I’m not sure. It’s hard to know whether I’ve exposed myself to the virus, as I’m guessing you know if you’ve followed the literature.
Mark Brady
Jul 25 2020 at 12:50am
David, I’m glad to hear that you are healthy. But you’re not “old.” You’re three years younger than me and I don’t regard myself as old. Neither, I suggest, should you. You may well have twenty or thirty years of life in front of you. That means you are not exactly old. Yes, I dare say that you draw an occupational pension, but that shouldn’t define old, particularly since you still get paid to write and speak, and in other respects are very much occupied. And a good thing too, I might add.
David Henderson
Jul 25 2020 at 10:31am
Thanks, Mark. I actually think of myself the way you think of me. My point is that in the data discussed in the Covid 19 context, I am old.
I do appreciate your appreciation. I’m also glad that you’re so intellectually active. People who take your classes get a rare experience-good (to use Nelson’s term) gift.
Mark Brady
Jul 25 2020 at 4:15pm
Thank you, David.
I suggest that there is now more recognition that a great many people over 65 are unlikely to suffer seriously from Covid-19 were they to catch it. That more nuanced approach is welcome.
Rebes
Jul 25 2020 at 7:52am
“Neither …”
That was my implicit criticism of your article. The population doesn’t fall neatly into two groups. There is a huge segment in the middle consisting of people who might not die if they get infected, but who are at risk of developing other serious health issues. It’s really this segment that drives public policy decisions right now.
David Henderson
Jul 24 2020 at 11:25pm
One thing to be aware of, Rebes, is that it’s hard to put oneself at risk when various rules, government and private, prevent it.
For example, I was engaged in negotiations with the Middlebury Institute of International Studies to teach their International Trade course this fall. We were fairly close on price. But I made it clear that I have zero interest in teaching on Zoom. They’re doing all their classes this fall remotely.
Mark Z
Jul 25 2020 at 2:10am
It’s also largely pointless to put oneself at risk of getting the virus while lockdown is in place since you’re not going to be interacting with many people anyway, so the social (and even personal) benefits of exposure are severely reduced. Lockdowns render immunity somewhat moot (not entirely moot of course, but somewhat).
Jon Murphy
Jul 24 2020 at 10:01pm
Fascinating read. I learned a lot, such as the fact COVID19 is the name of the disease and not the virus. I’ve been using COVID19 and SARS-CoV-2 interchangeably. I also found the tidbit about the fastest vaccine being 4 years interesting. I hadn’t realized the process was that long.
One point I want to push back on a little. You write:
I’m a bit skeptical on this point right now. I suspect part of the reason we didn’t see the virus spread or be as deadly in schools is because the schools were all shut down rather quickly. It wouldn’t surprise me to see the young-person mortality numbers rise with a full reopen.
In short, I think the claim is strong given the conditions. But you and Charley are far more familiar with the data than I am, so I will happily be corrected.
David Henderson
Jul 24 2020 at 11:18pm
You wrote:
Thanks.
I think that’s right. But also I often see kids together in my neighborhood who don’t look as if they’re in the same family: e.g. 3 teenage boys or 3 teenage girls, all roughly the same age. So unless there are a lot of triplets non-identical triplets running around, I think there’s a fair amount of contact.
But the more important point is that the infection fatality rate for young people with COVID-19 is very low.
Michael Byrnes
Jul 26 2020 at 6:49am
There may be a meaningful difference between small groups of kids interacting outside and putting hundreds kids together indoors several days per week.
David Henderson
Jul 26 2020 at 10:38am
True.
Mark Brady
Jul 25 2020 at 4:35pm
Jon writes, “I suspect part of the reason we didn’t see the virus spread or be as deadly in schools is because the schools were all shut down rather quickly.”
Your statement prompted me to search for stories that addressed this question, and this is what I found.
“The report showed that severe cases of COVID-19 were very rare among both Swedish and Finnish children aged 1 to 19, with no deaths reported. A comparison of the incidence of COVID-19 in different professions suggested no increased risk for teachers.
“Children made up around 8.2 percent of the total number of COVID-19 cases in Finland, compared to 2.1 percent in Sweden.”
https://www.reuters.com/article/us-health-coronavirus-sweden-schools/swedens-health-agency-says-open-schools-did-not-spur-pandemic-spread-among-children-idUSKCN24G2IS
Jon Murphy
Jul 26 2020 at 8:28am
Awesome. Thanks!
Charley Hooper
Jul 26 2020 at 2:23pm
Here’s some more data:
YMCA daycare centers in New York City that serve 40,000 children have stayed open during the pandemic and there have been no reports of coronavirus outbreaks or clusters.
Separately, Brown University economist Emily Oster found that among 916 daycare centers serving more than 20,000 children, just over 1% of staff and 0.16% of children were confirmed infected with the coronavirus.
Jon Murphy
Jul 26 2020 at 3:04pm
Fantastic. Good news indeed.
David Henderson
Jul 26 2020 at 3:35pm
Thanks, Charley. In retrospect, we should have put that in our analysis.
Michael Pettengill
Jul 27 2020 at 4:41am
So, infection control, isolation of those infected, suspected, or in contact has prevented spread.
That is preventing herd immunity.
Also preventing complications, hospitalization, death.
Scott Sumner
Jul 25 2020 at 12:02am
Thanks David. I’m a bit more optimistic about vaccines, although of course I’m just relying on what I read. I suspect that one reason the stock market is doing pretty well is that investors expect a vaccine this winter.
Michael Pettengill
Jul 27 2020 at 4:37am
Schools aren’t open in New England, but we see regular reports of healthy kids dying. Just for NH:
https://www.wmur.com/article/new-hampshire-inflammatory-syndrome-mis-c-in-child-first-case/32646258
https://www.wmur.com/article/nashua-health-officials-worried-about-uptick-in-covid-19-infections-among-young-people/33315734
“State epidemiologist Dr. Benjamin Chan said 4-5% of those hospitalized are under 30, so young people should be concerned about their health.”
NH had a early spike, many associated with a few long term care facilities, as well as Boston cases seeded by a health care company meeting in February. But restrictions on gatherings, distancing, mask wearing, the number of new infections is much lower. But that also means the number of people with any immunity is very low.
And any of the 4 endemic coronavirus providing protection is unlikely given everyone over the age of five has had them all more than once, with those in long term care are certainly getting them regularly. Those in long term care are vaccinated for the complications from common cold, pneumonia viruses. Yet they are at highest risk of COVID-19.
The population exposed to the virus in NH is very low by all indications based on the low positive rate for PCR and low rate for the much smaller number of antibody tests. “Anyone” can get a test, but the results are not timely for other than institutions.
But let’s assume 0.1% for 0-10 year olds, with swag 40 million population, so 40,000 kids dying from COVID-19 quickly or in a month from “MIS”.
Charley Hooper
Jul 27 2020 at 1:00pm
John Ioannidis of Stanford estimates the infection fatality rate of COVID-19 to be 0.05% for those under 70. The IFR for young children must be much, much lower.
Schools have been opened in Australia, Austria, Denmark, Finland, Germany, New Zealand, Norway, and Singapore without a resulting increase in coronavirus infections rates.
“Our interpretation is that it may be that the children aren’t that important for the spread of infection,” said Dr. Tyra Grove Krause, State Serum Institute, Denmark.
One reason for the absence of infections in schools could be that children below 10 have fewer of the receptors the virus uses to enter the body, said Prof. Herman Goossens, European Union task force for researching COVID-19.
Dwight Mattix
Jul 27 2020 at 3:33pm
How about let’s not assume 0.1% fatality rate for children? No idea where that estimate came from.
For children how about an order of magnitude lower than the CDC’s 0.0065% for “Infection Fatality Ratio, Overall†”
That is from CDC Scenario 5 which “represents a current best estimate about viral transmission and disease severity in the United States, with the same caveat: that the parameter values will change as more data become available.”
https://www.cdc.gov/coronavirus/2019-ncov/hcp/planning-scenarios.html?fbclid=IwAR1EMqQQ1IuQ96-BLhekJWYWl9GpUGNRWomKs_ti6yoW2SOaxsoZXp5BqZs
Tom DeMeo
Jul 27 2020 at 9:11am
To take NYC as an example, they still would need to endure more than 3X the infections they have already endured to achieve herd immunity. An NYC level of burn would take most of a year at minimum.
In NYC, this resulted in a brutal economic shutdown. Without outside help, things would have been considerably worse.
You cannot have a burn rate that would support a strategy like this without inducing an emergent order economic shutdown.
You cannot get a community to do this. They won’t tolerate that amount of pain. Instead you will get a failed cyclical version of this strategy
Charley Hooper
Jul 27 2020 at 12:54pm
Why do you say that NYC would need more than three times the number of past/current infections to reach herd immunity?
Tom DeMeo
Jul 27 2020 at 4:49pm
Fair enough. My intention was to roughly estimate they are only about a 1/3 of the way to immunity, and I phrased it incorrectly. That was just using reported infections x 10, and of course, that’s still just a guess on my part.
What information would you cite? Wouldn’t the point still hold?
Charley Hooper
Jul 27 2020 at 8:01pm
There is, of course, much that is unknown about the threshold for herd immunity to SARS-CoV-2. But consider these three pieces of information:
(1) Some epidemiologists are estimating that herd immunity for SARS-CoV-2 can be reached if 60-70 percent of the population is immune.
(2) Studies suggest that 50 percent of us have innate immunity to a SARS-CoV-2 infection.
(3) There’s evidence that more than 20 percent of New York City residents had already been infected by the end of April.
Add 50% and 20% and you get 70%. Has NYC already reached herd immunity? Perhaps. Daily new cases have dropped substantially since the end of April.
Tom DeMeo
Jul 28 2020 at 11:24am
Your theory postulates that 50% of the population may have “immunity”. Any subtle distinction here could have deadly consequences. Then you assume that if 10-20% of a population gets the virus, we may have achieved herd immunity. Break that down:
50% starting vulnerability
15-20% can get sick in accelerating fashion with great consequence, but once we burn through them, the virus stops spreading at an increasing rate.
50% vulnerability produces rapid spread and social disruption
30% vulnerability produces depression of spread and limits social disruption
Does that sound likely?
Can anyone make such assumptions with our current level of understanding of transmission?
How much of the reduction in infections is due to the massive behavioral changes of NYC and how much is due to immunity? Its likely a complicated mix. Asserting that it is primarily due to immunity is a very very dangerous bet to make.
Charley Hooper
Jul 28 2020 at 12:54pm
Tom DeMeo:
Does that sound likely? Yes. The virus moves through society with relative ease until a threshold is reached and it finds fewer vulnerable candidates. Then transmission slows and new cases drop. It fits the pattern we’ve seen in NYC.
Tom DeMeo
Jul 29 2020 at 11:06am
Charley,
Transmission is a function of vulnerability AND exposure. The NYC pattern has vulnerability going down and exposure remaining highly controlled. Herd immunity will not work if you increase exposure faster than you reduce vulnerability.
Herd immunity is gradual. It is not a threshold. The only real threshold is R0<1. We still have plenty of people who can get sick.
Dick White
Jul 28 2020 at 10:11pm
I don’t understand the assertion that masks/lock downs won’t reduce covid infections only spread out/delay the emergence. Does this mean that if I take these precautions, I will likely avoid covid infection (a reduction) but eventually someone else will become infected cancelling out the reduction that I generated?
Stremove.com
Jul 29 2020 at 4:00pm
There is, however, a widespread consensus among economists and public health experts that lifting the restrictions would impose huge costs in additional lives lost to the virus — and deliver little lasting benefit to the economy.
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