Ben Neuman, a professor at Texas A&M-Texarkana, is one of the world’s top authorities on coronaviruses. He’s said to have grown more SARS-type viruses in the lab than anyone else alive, and he was on the panel that gave the coronavirus now upending our world its official scientific name: SARS-CoV-2.
Neuman is also one of the world’s most genial explainers of science. Via YouTube and the Facebook group “Dr Ben Neuman’s Science Group,” his wife posts videos of him answering all kinds of questions about the coronavirus — some highly technical, some from children.
Normally, with these expert Q&As, I ask all the questions. But for this week’s, Neuman also agreed to field some from regular Houstonians. — Lisa Gray
After exposure to an infected person, what’s the soonest that I could show symptoms? And what’s the latest? — Roseanne
This is a good question. It has been very hard to tell when anybody has been definitely exposed. Even if you know the day or the time, you’re never going to know exactly which virus, from which breath, did it.
So what we’ve got is an estimate. I think the earliest we’ve seen is around three days. The average is something like a week.
This is for the onset of the first very mild symptoms, even if they become something worse. You are not going to know you’re infected, and it’s going to gradually ramp up over about three weeks.
The longest amount of time it could take for you to show symptoms depends on the power of denial. I think that, if a doctor were to look at you, clinical symptoms can be pretty reliably detected between seven and 10 days. But people who show symptoms often don’t go to the doctor. They try to walk it off.
Or people think that something else is the problem. For example, it’s allergy season right now: A lot of allergy symptoms look like early COVID. It’s tough to tell without the actual COVID test.
If someone had COVID-19 four months ago, will it show in the antibody test? — Amy
Totally: That is when it would show up.
It’s not going to show up until about a month after the point you caught the virus. That’s when you would first get a good antibody positive test.
After that, we think it ought to be detectable for probably at least a year, maybe a couple of years.
How does herd immunity work? — Martin
Very well on paper and in mathematical simulations, but it’s somewhat more problematic in the real world.
The idea is that mathematically, if you get enough people who’ve survived and are immune, who can’t spread the virus, it limits the how much the virus can spread. Like mask wearing or vaccinating, it’s another way that the world is going to come down and crush this virus out of existence.
But it’s a long way to herd immunity. There will probably never be enough people exposed. And once you’re exposed, it looks like the immune response drops off quickly.
So we don’t know whether herd immunity is even possible with a virus like this. This virus seems more like the sort of thing you’ll get every year to two years, rather than the sort of thing you’ll get once and just be over forever — which is unfortunate.
That means we need to do something besides rely on herd immunity to get rid of this virus.
So how can we get rid of this virus? — Lisa
Here’s what we can do: Stop it from spreading. Absolutely drive it into the ground. Every individual transmission means one month more of this life. And I’m sick of it.
I go to the grocery store about every 10 days. Practically speaking, how long do I have to stay home after that for it to be safe for me to see my daughter and granddaughter and not worry about infecting them? — Linda
If you’re wearing a mask when you are in that supermarket, you should be all right. That mask is definitely going to limit the odds that you spread the virus to anybody else in the store, and it also probably limits the odds that you catch the virus.
And boy, every 10 days? You’re really good at planning. I run out of something about every three days. My hat’s off to you.
If someone believes they might have been exposed — if they’ve been in a higher-risk situation than a supermarket — how long should they wait before being around someone vulnerable? — Lisa
What you should do is get a test. Waiting is okay, and eventually the virus will go away. But that “eventually” is about a month from when you catch the virus to when you’re probably over the virus. And in some cases, there are people that hold onto the virus for two months or longer. So you can’t guarantee after any period of time that you are 100 percent virus-free. You need to get a test.
In this case, the antibody test is not going to be useful: That doesn’t even start to register as positive until you’ve had the virus for about a month. You’re going to want the actual annoying painful swab-up-the-nose or back-of-the-throat test. You probably want to wait for about a week after you had your high-risk exposure because if you’re positive, it takes about that long to have enough virus in your system for the test to be able to pick it up.
How do you calculate specificity and sensitivity when addressing effectiveness of serological tests? Are those dependent on assumptions made about the spread in a certain community? — Olga
What we’re talking about here is, how do people that are making the test know if that test is good? You want to know that you are going to pick up all of the cases that are genuinely infected with SARS-CoV-2 — that’s sensitivity. And you want to know that you’re getting as many of those as possible — a high number of true positives, low false positives, and low false negatives.
You try out these tests in a laboratory. For example, you run your test on this coronavirus, and a mouse coronavirus and SARS one. It should only give a positive for the one and not the others. That’s selectivity: Can you tell it’s this virus rather than the others?
As for sensitivity: When you’re getting a new test approved, there are companies that will send you 20 little mystery vials. Maybe they have virus particles; maybe they don’t. (None of them have actual live virus. They use a little piece of the virus or a little piece of antibody from somebody who either definitely had laboratory-confirmed virus or definitely didn’t.)
Then you get to do the Pepsi Challenge. If you get them all right, your lab passes. Or maybe 19 out of 20 right: that’s good enough for emergency use authorization — the FDA says it’s good enough to use right now. Later, when this has all blown over, they’ll come back and make sure that you’ve run these tests more thoroughly and that you get proper selectivity and sensitivity worked out..
In the 18th century, injections of live smallpox virus were successfully used to vaccinate people against the disease. Do researchers know if repeated community exposure to small quantities of coronavirus would function as a vaccination against a severe disease event? — Dana
We do not know that. Right now it looks like the answer is probably no.
Here’s why I say that. There are some people who have laboratory-confirmed coronavirus, but afterwards you look at the antibodies and say, “All right, immune system, what did you come up with?” And the answer is, “Almost nothing.”
Your body can shut this virus down with mucus and using the “innate immune system” — those are the cells that are going to do a job and then they’re going to go home at 5 p.m. They’re going to clock out, and they will not remember what they’ve done after that.
Though you can knock the virus out that way, it doesn’t give you lasting immunity that would protect you against re-exposure. That’s why we’re thinking that it probably doesn’t matter how much dead virus you inhale unless you get a strong immune response — which you don’t always get even with a real infection.
How many other coronaviruses are out there in the world? Should we worry this won’t be the last one that jumps to human beings? — Lisa
Look, unfortunately, it’s guaranteed this won’t be the last one.
There are many coronaviruses out there, and many corona-like viruses. They’re in everything, all kinds of animals. We’ve found them in axolotls. I don’t know if you know them: They’re giant Mexican salamanders with pink gills out the side.
Various kinds of fish have related viruses. Frogs. You get lots of these viruses in bats. There was a neat paper that showed a virus from a bat jumping to Malayan porcupines and five different kinds of field rats.
Basically, we know about as many coronaviruses as the times that we’ve picked up an animal and stuck a swab in its mouth. For most animals, we haven’t done that even once with the entire species.
Every time people look in bats or other kinds of animals, they tend to pull out a couple new branches of the coronavirus family tree.
The question is, when and how will these things spread to humans? That is pretty much up to chance.
But there are so many of these out there. And from the early studies, of the viruses that fall into the category “SARS-related coronavirus,” about a quarter of those seem to be able to enter human cells with no further mutation required.
So yeah, it’s going to happen. We need to get better at this. A lot better.
When developing a serological test, how does one choose a site on the spike protein? Do some tests use many sites? — Olga
This question is basically: How do you actually make a test that will find antibodies against the virus?
Around 40 tests have that emergency authorization. They’re all slightly different. They look for different things, and they tell you different information.
One way to do the test is to look for general antibodies. You’re basically putting out bait and looking for antibodies that will stick to it. You can put out the whole spike. You can put out the top of the spike or the bottom of spike. You can put out a thing called the receptor binding domain, RBD — that’s the business end of the spike that’s going to grab onto your cell. You can potentially find antibodies to all of these.
So finding antibodies to any part of spike means that a person was infected, or at least got a great big exposure at some point in history. That doesn’t say what’s going on now with any degree of certainty. It just tells you what probably happened sometime in the past.
Now, there are other versions of the test where you can look for neutralizing antibodies. This is tougher to do, but ultimately, this is the test that everybody wants. Those are the tests that would say whether you would potentially be protected.
For that test, you’re trying to see if your antibody can come in between the virus and the cell and prevent those two from coming together and starting an infection. There are different ways to do it, but essentially, it’s a man-in-the-middle thing, only it’s with an antibody in the middle.
But even there, it depends what serum you’re putting in. The easiest way to get antibodies is just with a little blood prick — but these are not the antibodies that are going to protect you in the long term. These are mostly going to be things called IgM and IgG, which are two of the five big categories of antibodies. (And then there’s subcategories of those. Immunologists love this stuff.)
The antibodies that are gonna protect you are called IgA, Immunoglobulin A. These are the only antibodies that get made in any sort of abundance in your nose, mouth, throat, intestines — all the places where the virus is going to come in. The idea is, if you make a good neutralizing able-to-stop-interaction IgA, that’s going to prevent you from getting infected. In my book an ounce of prevention is better than the whole pound of antibody cure. And in everybody’s book, I think.
For those people who still show symptoms months after infection, what’s the probability that that’s due to the virus finding a reservoir in the body versus antibodies or fragments of antibodies or virus that are unable to cause disease that are causing such problems? — Olga
That’s a great question. The answer depends on, is this person still virus-positive? It turns out, the best way to check for that is a fecal sample.
The virus will stay down in the intestines longer than it stays in any other part of the body, and that gives a good readout. In the big hospitals in Wuhan right now, they are not releasing people until they’ve had two consecutive negative tests, and they have to be fecal tests.
So if you’ve got somebody that’s having symptoms that feel like COVID, and it’s been a month or two since they were infected, the best thing to do is, obviously, check to see if they are still infected — because it’s possible. It’s not the middle of the bell curve that somebody would have the virus for this long. But out on the tails of the bell curve, things get weird.
We know that SARS-1 left a lot of scar tissue inside the lungs. So with SARS-CoV-2, you could have this scar tissue, and then a little bit of pollen or a little bit of some other disease, even bacteria, would make it feel much worse than it ever did before. It would be the damage the virus left behind, rather than an active virus infection. That would be the second most likely scenario.
Way down the list would be reinfection, but this is also possible. It’s just very difficult to confirm, because the virus hasn’t changed that much — mutated — since the first time you got it. And if you did get reinfected, you probably caught it from somebody you gave it to. So it’s not going to be very different, and there wouldn’t be a good way to prove that it’s reinfection as opposed to persistence.
We know coronaviruses do persist — just live inside of cells — for up to years in a mouse. Nobody’s shown this yet in a person, and this will be kind of weird when that happens. It could happen in neurons, like nerve cells in the spinal cord, which live for a very long time, longer than other cells. But right now, it’s difficult to show that these are even infected. We know they’re infect-able, but it’s hard to say whether they are meaningfully infected.
So that’s where I would be looking if somebody did show up as being consistently positive for a long period of time: in neurons.
What’s the most surprising new research that you’ve read recently? The most interesting result? — Lisa
The coolest paper from last week is the one in Vietnam where they’re looking at bat guano farms. They’re harvesting bat poo from these little bat roosts, and they’re finding the virus that these bats have.
Then nearby, there are farms where various food animals are being grown or caught. They’re showing that these food animals start out with low levels of the virus from the bats. But as they go up the food chain — as they go from the farm to the little market to the big market to the restaurants — they get more and more virus in them as the virus spreads and it spreads to different species.
This is exactly what we think happened in Wuhan. But this study is from Vietnam, it’s from six years ago, and it’s with two different kinds of bat coronavirus. These are all the SARSes that could have been but that thankfully we avoided. It just shows how much of this stuff is going on out there.
Viruses have been called the dark matter of the biosphere. They’re out there. They have big effects on everything. And we are just not good at tracking them yet. You look under the cover of what’s going on, and it’s fascinating and terrifying at the same time.
In Texas we’re watching the numbers of people infected with COVID-19 soar. What do people need to know? What should we be thinking about? — Lisa
Wear a mask. There are a tiny number of people — like some people on the autism spectrum — who can’t wear masks. But everybody else, just wear that mask.
Preventively? Proudly? Actively? I don’t care. Put something on!
A lot of people, looking at this from a risk-management point of view, are saying, “Well, if I am super-susceptible, then I should wear a lot of coverings. And if somebody else is not susceptible, they should just be able to go out in society and do whatever.” But that is the thinking that got us into this mess. It’s not going to get us out.
You have to have everybody together doing the same thing because the virus will spread to those people who aren’t wearing masks. Today you may prevent that person at high risk from getting infected, but you’re closing the front door and leaving the back door very, very wide open, because everybody has some human contact. Everybody has to have some. We’re social creatures.
We’ve got to ruthlessly stamp out this virus completely. From everybody. We can’t allow it to grow anywhere.
Masks are cool because they let us do almost everything we want to do — just with a mask on.
It’s annoying, but whatever. I’m adjusting. I feel like we can all do this, and if we did, we could get rid of the virus.
So with masks, we can do anything we want? Could I go to a stadium football game if I wear a mask? — Lisa
If you’re spaced out and wearing masks and outside: Well, these are all things that lower the risk. But I feel that any activity that gets thousands of people together and fired up and shouting is going to be higher-risk than watching sedately in your own home.
That stinks. But yeah, I would say, let’s just watch football from home. Let’s not be there. That’s the safe way.
Is it safe to see my extended family outside at a picnic table? — Lisa
Bam! Wear a mask, and you’re good.
People think that no transmission happens outside. That’s not true. It’s much lower — you have something like four or five times higher risk of transmitting it if you’re inside — but it’s not nothing.
So wear a mask when you’re around people, regardless of whether it’s inside or outside, and try to avoid being in the same room as a person that you don’t have to be in the same room with — unless, of course, you’re living with them.
The Chronicle’s photography staff has been out on the street — they’re crazy careful —-so a couple of them went for swab tests. One got a self-swab, and she wasn’t happy. She has no confidence in the results of that test and would have prefer the “brain poke,” as they’re calling it. What are the pros and cons of the self-swab vs. the brain poke? And the reliability of each? — Scott
The con of the brain poke is that you gotta be in the same room as another human being to get it — until we get a brain-poking robot, anyway.
We’ve shown that this virus can grow at the back of the nose, but that is more where the flu virus grows. The people trained to do these tests were mostly trained on flu, and basically, they’re doing a flu test on you. I mean, it’s a COVID test, but that’s where they swab.
You would probably get a more accurate result from a fecal sample. Those are gross, but they’re more accurate. So yeah, we need to get used to that.
Or even a throat sample would be more accurate than the brain poke — that is, if you can make yourself gag, really get it down in there.
Drive-thru testing relies on your doing swab parts yourself, or coming up with the sample yourself in whatever form that takes. That’s the safest way.
I did the test with the short swab in the back of the nose. Is that reliable? — Scott
Reasonably, but not 100 percent. You need to be pretty well infected before that comes up positive.
But it is reliable. It’s the most reliable one we have. Until we start doing the fecal test — and really that’s the same test. It’s just performed on a more reliable source.
Once and for all: Did the virus escape from a lab in China? — Scott
Was it made by evil scientists in a skull-shaped mountain? [Laughs.] No.
This virus is a thousand nucleotide mutations different from anything that any human has ever seen before. The virus makes mutations slowly. And we know that viruses like this have a thing called an “error threshold,” which is how many random changes they can stand before they fall apart and die.
The error threshold seems to be about five on these. So we’re way beyond the threshold of what just randomly putting mutations into a thing and plugging them in and hoping it works is going to get you. This is something that could only exist through long-term natural selection, which is exactly what you would get in bats and cats and whatever animals there are in Asia.
[email protected], @LisaGray_HouTX