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The Role of Children in the Wuhan Epidemic
In a terrific interview during the most recent Ricochet Podcast, Dr. Jay Bhattacharya of Stanford Medical School describes two possible models for the Wuhan virus epidemic. In one model, the virus has a high fatality rate but spreads slowly. In the other, the virus spreads quickly and has already infected a large number of people, which make the current fatality count a small fraction of the total population and hence the true fatality rate for the virus relatively low. (Dr. Bhattacharya, while cautioning that there is a wide divergence of opinion among smart and capable medical professionals, cautiously subscribes to the second view.)
I would like to believe that the virus has been in the population longer than the we generally think, and that many people have been exposed and have already recovered. We don’t have enough information to inform that belief, which is why antibody/serum testing is of paramount importance in understanding this epidemic and tailoring a response to it.
One of the things that makes me uneasy about the idea that it has spread widely in the population is the apparently distinctive nature of the respiratory distress it causes in those most grievously afflicted. If the virus has been in transmission in the US since January is it possible that the medical community didn’t notice the critical and fatal cases of the disease that, it seems, must have occurred during that time? Could they have been mistaken for seasonal influenza deaths? Is the fact that they would have clustered in an elderly and already ill population, one susceptible to failure during the winter flu season, sufficient to explain why the earliest cases might have gone unremarked?
This thought prompted me to go looking for information about seasonal influenza epidemiology, about the pattern of transmission of the “regular” flu during our normal flu season. I came across an interesting paper published online by the National Institutes of Health, titled The Shifting Demographic Landscape of Influenza. That paper contains this observation:
Prior to the introduction of a novel pandemic strain, most of the population is susceptible. The pandemic initially sweeps through the most connected portions of the populations, including groups of school-age children, leaving a wake of temporarily immunized individuals. The remaining susceptible population will consist of less connected portions of the population.
That “less connected portion of the population” is, generally speaking, adults.
Now consider what we know of the Wuhan virus. It is certainly a “novel pandemic strain.” It is moderately contagious through normal social contact. It appears to be asymptomatic in as much as half of the infected population. Serious symptoms are dramatically biased toward the elderly and already ill, with symptoms conspicuously mild in young people. In older infected populations it rapidly causes serious and distinctive respiratory failure.
Given all that, I wonder if it’s possible that the virus has spread widely through the school-age population, but much more slowly in the adult population and only rarely among the elderly. The paper suggests that such a partitioned epidemiology is plausible, and it might explain how the disease could have traveled widely without conspicuous early eruption on the national scene.
The paper also suggests that, while the first iteration of the novel influenza is concentrated in the school-aged population, the second iteration is experienced primarily by adults, given the temporary herd immunity gained by young people in the first wave.
Published in General
Given all that, I wonder if it’s possible that the virus has spread widely through the school-age population, but much more slowly in the adult population and only rarely among the elderly. The paper suggests that such a partitioned epidemiology is plausible, and it might explain how the disease could have traveled widely without conspicuous early eruption on the national scene.
Henry, I think that is a very plausible scenario. Here in Southern California, we are exposed to many thousands of Chinese nationals who regularly transit back and forth to China and as a result it kinda hard to assume that many in Southern California were not exposed by early January to the disease. I have an attorney friend who had a family get together in late December. One of his relatives who attended was from St. Louis. She came to the event and stayed in LA for a few days and then went to visit the Bay area for a few days before returning to St. Louis. Bu the time she returned to St. Louis she had flu like symptoms and was diagnosed there as having the CoronaVirus. Such a story is not impossible. By December 31 st, 27 people had already been diagnosed with the Corona Virus in Wuhan, and there were no restrictions on travel for another month.
Please show me the evidence for this.
How is this defined?
There aren’t a lot of thoroughly tested populations, but the sample of the Diamond Princess cruise ship, if I remember correctly, reported that 51% of those who tested positive (619 individuals) were asymptomatic. (How many, if any, who later became symptomatic I don’t know.) Testing also showed that those with milder symptoms were more likely to generate false-negative test results, which would suggest that asymptomatic individuals would be more likely to be missed in population testing, and so tend to represent a larger sample than testing would indicate. There’s a piece at Watts Up With That that reviews the Diamond Princess numbers, should you care to review it.
This is really the thrust of the linked article at NIH, that school children represent a more “connected” population and that virus transmission occurs first in that population. Subsequently, the population of less connected people — i.e., the population of not-school-children — becomes the target population for further spread.
I think this theory is plausible. I’ve thought it for two months now–that some of the high rate of death for the flu this year has been due to this virus or a variant. Flu deaths, according to the CDC, are usually caused by pneumonia. This is from the CDC:
It would so helpful if the Google-Microsoft-IBM consortium would use their supercomputing capabilities to “map” the human immune system to see what pathogens it is fending off at any given moment. We could take a secretion sample and see what’s in it the way we presently look at DNA. I think that is the only way we will ever get the better of the viruses out there. We are surrounded by them.
That said, the absence of this virus in children is the weirdest thing about this bug. If it’s true that they’ve been exposed and have active antibodies against it for some reason, that might explain it. Or for some reason they have an inherited resistance to it.
But I can’t help wondering if it is possible to engineer a virus to target a specific age group. I know that aging is genetically determined. So it does not seem totally ridiculous that a virus might be engineered to do that. Was this was a bioengineered virus that escaped from the lab? Perhaps it was developed not for diabolical reasons but rather to develop a vaccine or treatment against something similar to it produced by a terrorist of some kind.
I keep reading that this virus is not a bioweapon because it doesn’t work well enough to be one. I don’t know what newspapers the people who say that are reading, but it’s not the same ones I am. The victims remain alive long enough to spread it very well to a lot of other people.
I think when we figure out definitively why the virus did not infect children the way it infected adults, we’ll understand it better. I find it hard to believe there was that much random exposure to this virus that an entire generation of children globally was able to develop antibodies to it before the rest of us even knew it was out there.
I’m not sure that there is an absence of the virus in children. Being asymptomatic and being virus free may very well be two very different things. Almost all of the testing to date is among the symptomatic population. If children tend to have no symptoms or only very mild, cold-like symptoms, then very few of them are likely to be tested.
It will be interesting, when serum tests are readily available, to determine the prevalence of old infection in the population of those who have only the mildest symptoms.
I agree completely. This is one of the parts of this story that won’t be known for a few years, if ever.
If only we could get a good look at the human immune system workings and components the way we look at DNA.
I’ve always told my kids that the immune system is “the final frontier,” to borrow the phrase from Star Trek. :-)
When Iceland started open testing they found about 50% of the 963 who tested positive were asymptomatic. As a result, Iceland shows an infection rate almost double that of Italy but with only 2 deaths and 18 in critical or serious condition.
One can’t help but wonder about this, especially since children’s immune systems are immature. Having read articles on the negative effects on Wuhan virus patients of certain drugs used to treat hypertension and diabetes, drugs which I suspect are almost never used with children, I wonder if there may be other medications commonly used by adults, especially as they age, that make succumbing to the virus more likely. Perhaps it is not exactly the co-morbidities that make the virus so virulent in some, but rather the drugs being used to treat those ailments. One of the docs interviewed recently on Fox expressed amazement that diabetes was such a strong co-morbidity in the disease, saying he hadn’t seen that with a virus before, but perhaps that isn’t the point.
That’s a really good question about medicines that kids don’t take but adults do. That would make a lot of sense too.
I have been wondering about antacids. I had gastritis recently and so I had to enter that aisle in the drugstore. My word, Americans take a lot of antacids. I know that stomach acid kills the HIV virus. I know that there’s some tiny HIV DNA somewhere in the covid-19 DNA. I can’t help wondering if its something we’d never think of. And it’s also something hardly any kids ever take.
Ah, it only affects the Gr’ups.
Henry,
Something like what you are hypothesizing must be true. We don’t have exact numbers because the Chinese believe in propaganda like all good Marxists. Their misinformation has left the world without the precise guidance that it needs to make best judgments.
We are still navigating by the seat of our pants. The American testing results are now pouring in. In the next couple of weeks, we’ll have a good fix on these numbers. We’ve got to not go crazy right now.
Good post.
Regards,
Jim
While the most dire scenarios are rapidly falling out of favor, neither do we we appear to be reaching a happy state of herd immunity from an early, untested, wider-than-expected spread.
I don’t know if we have reliable antibody testing to determine rates of past passive exposure versus an active infection. I don’t know enough about the methods.
The Iceland sampling seemed to reaffirm the Diamond Princess sample — 50% have no symptoms, some smaller, variable percentage are seriously ill and some variable small subset of the critical die. We don’t have numbers for people exposed who don’t have an presence of the bug—why did 83% of the heavily exposed Diamond Princess population test negative?
It will not be possible to completely wait out the bug with isolation strategies because groceries, carry out, emergency services, trucking must persist. So rather than achieve diminishing returns at greater costs, maybe it’s time to train hard for self-protection, mask the sick and vulnerable and go back to work while better treatments and other newly deployed resources come on line to offset the increased exposure risk.
OB, I agree: it seems likely that herd immunity will have to be a gradual thing, not something that’s achieved in one, or perhaps even several, cycles of the virus (that is, through infection without a vaccine).
What I think is significant about the possibility that the Wuhan virus traveled widely before we noticed it is not that it might confer significant population immunity, but that it might explain the sudden and alarming eruption without requiring that this thing is burning like a wildfire despite our efforts to slow its spread. If it appears not to respond to efforts to limit its transmission, I’d like to believe that it’s because we’re looking at transmission that already occurred, before we tried to stop it. (And it would be nice if the lethality were correspondingly lower, as a consequence of that large denominator.)
An in-law who is is a high-level consultant contracted chronic bronchitis after travel to China. It has been chronic for two months so the docs don’t think it’s COVID—test was done but results take 3-6 days(!?).
She is now hospitalized for treatment of pneumonia. However, all respirators are in use so she does not have one. She cannot have visitors because the hospital is in semi-lockdown mode.
Fairfax County VA (population 1.1 million) has fewer that 150 COVID cases and two deaths. So if this hospital in one of the wealthiest communities in the US is already out of respirators, that is more than a little worrisome.
I harbor a suspicion that a lot of hospitals will respond more slowly than they have to because of administrative inertia and the perception that disturbance of routines causes hidden costs and malpractice risk.
Given that most who are diagnosed with the Wuhan virus do not require a respirator, one has to wonder if perhaps there’s a simple logistical problem going on here. Maybe I’m naive, but it seems unlikely that respirators would already be in short supply there.
Maybe it is a coincidence of a spike in other respiratory conditions in that particular hospital given that there just can’t be that many serious COVID cases yet. But given all the attention given the issue of availability of respirators it is stunning that a leading hospital has no sourcing Plan B at this time.
Yes, it is.
And I don’t want to appear unduly skeptical, but I’d probably want to hear an explanation before I concluded anything about this one instance. A great many people — even competent, smart, dedicated people — are miserably poor communicators.
Among people with health problems, COVID 19 presents itself in many ways so doctors have likely misdiagnosed patients, especially early in this pandemic, presuming that their patients suffered some other ailment or chronic problem. If you’ve been studying the comorbidity numbers, hypertension is the number one chronic condition shared among those who’ve died from the COVID 19. The problem is, COVID 19 patients are often dehydrated and anorexic (too sick to eat or drink), and suffer from fever, general pain and malaise. Typically, these symptoms are associated with the flu; people with the flu are rehydrated and given NSAIDS, but both these treatments are now known to exascerbate COVID 19 pneumonia, especially if those patients were hypertensive to begin with.
It is also possible that other common non NSAID blood thinners, like Plavix, Warfarin or similar drugs, are worsening COVID 19 pneumonia.
We have a lot still to learn about SARS CoV 2.