The Covid chronicles: Is herd immunity still possible?

With Covid raging in India and Brazil, it’s a strange time to be talking about herd immunity, but a cluster of scientific articles are doing just that. 

How many people need to be immune to a disease in order for the population as a whole to be protected? The answer varies with the disease. For measles, which is very contagious, the estimate is 95%. Vaccinate that many (or wait till they get sick and grow their own immunity) and the other 5% will get protection simply from not being around anyone covered with itchy little spots. 

For the initial Covid strain, the best guess was that herd immunity would come when 70% of the population was immune. But as a planet, we handled the disease so badly that we’re not dealing with that strain anymore. Instead, we have a small raft of more contagious strains, so the bar we have to jump over before we reach herd immunity has probably gone from–oh, let’s say waist height to shoulder height. 

Oh, yes, lucky us.

Irrelevant photo: Wood anemones.

So far, the countries with widespread vaccination programs also have groups of people who refuse to be vaccinated–that’s in addition to some who for medical reasons can’t be. They also have groups who for social and political reasons haven’t been reached. The US and UK haven’t done as well at vaccinating ethnic minority groups as they have at vaccinating whites. When I last checked, in April, Israel had gotten only dribbles of vaccine to the occupied territories, saying they weren’t its problem.

And most importantly, the world at large has done a shit job of getting vaccine to the poorer countries. So all those pools of unvaccinated people are where the disease will spread and mutate and create new variants, each of which carries in its itty bitty little pockets the possibility of outrunning the vaccines that those of us who are vaccinated are so relieved to have. 

Israel has vaccinated just upwards of 60% of its population and has in large part returned to normal life, but that normality depends on keeping its borders largely closed and wearing masks indoors. Countries like New Zealand and Australia, which have in large part stamped out the virus, rely on tight border control and strict quarantine. How long they can or have the will to keep those barriers in place remains to be seen.

One article (the link’s above) says that the trick will be keeping restrictions in place once case and hospitalization numbers drop. Primarily, it says, these will be Covid tests and masks. 

And just so’s you know: There’s no agreed-upon definition of herd immunity. I’m going to skip the details and say only that this doesn’t make the conversation about it any clearer. For a sensible discussion, go here.

Some of the articles I’ve read say we’re unlikely to ever completely eliminate Covid. In countries that have been heavily (but not completely) vaccinated, it’s likely to continue circulating and causing deaths, but at dramatically lower rates.  

Sorry. It’s not the knock-out punch we were all hoping for, but it’s a hell of a lot better than the alternative.  

Dr. Anthony Fauci tells us not to worry about herd immunity.

“People were getting confused and thinking you’re never going to get the infections down until you reach this mystical level of herd immunity, whatever that number is.

“That’s why we stopped using herd immunity in the classic sense. I’m saying: Forget that for a second. You vaccinate enough people, the infections are going to go down.”

 

The search for a Covid pill

At least three of the big drug companies are working on pills to keep mild Covid from turning into severe Covid. If they succeed, they’d make Covid’s continued presence in our lives a hell of a lot more manageable.

The first days after the virus moves into a human host are its busiest. It sets up housekeeping in a cell and creates a family to admire its work. And then the family spreads out, setting up housekeeping in new cells. And so forth. It multiplies like mad, and that’s when we’d need to drop that little pill–you know: the one that doesn’t quite exist yet–down our throats to disrupt the sequence. 

Researchers have trolled through existing drugs, hoping to find one that would, by chance, do the job but so far haven’t come up with anything. Hence the search for new ones.

One that’s in development is a protease inhibitor, which would interfere with the enzymes the virus needs to multiply. (No, don’t ask me. I’m just playing parrot here.) Drugs that treat AIDS and hepatitis C are protease inhibitors, in case that gives you the same illusion of understanding that glowed so nicely in my brain until I realizes I didn’t really understand a thing.

Other drugs in development target the virus itself. That does’t glow quite as nicely and I’d love to say more about the process but that’s all I’ve got, although I can repeat that they’d disrupt the virus’s ability to replicate itself.

The companies are hoping to have the first of the drugs on the market by the end of the year. And they may end up being used in combination to keep the virus from evolving some form of resistance. 

Don’t give up, folks. We’ll get through this, even if life isn’t quite the same as it used to be.

It wasn’t perfect then either, was it?

The Covid testing dilemma

England’s pushing mass testing as a way to contain Covid. It’s free, it’s government approved, it’s somewhere between uncomfortable and painful, and it may or may not be a good idea. Let’s tear the numbers apart and see what we can figure out.

Since the schools reopened, secondary students–those are the older kids–have had to do quick Covid tests twice a week, and that’s been a bulwark of the program to keep the schools open while not letting the virus get out of control. 

The tests, unfortunately, have a reputation for being unreliable, especially when done by non-experts. Since the kids are doing their own tests, or asking their parents or three-year-old sisters to stick the swabs up their noses and down their throats, these are in the hands of the distilled essence of non-expert. One fear about relying on the quick tests has been that false positives will send a lot of people into isolation unnecessarily. So half of the positive tests were sent to a lab to be confirmed by the slower, more reliable tests, and only 18% of them were false positives. 

Irrelevant photo: Rhododendrons. Photo by Ida Swearingen

But wait, because we’re not done yet. Those numbers are from March, and Covid rates have fallen, at least in parts of the country. (Some hot spots remain, and I don’t know if numbers are falling there as well. Just put that possibility off to one side. The recipe may call for it later. If it doesn’t, we’ll stick it in the freezer.) The point is that where the number of cases is lower, everything changes

Why? Because the tests will crank out the same number of false positives, no matter how many people are infected. Find yourself a population of people who’ve never been exposed to Covid and the test will swear on any religious book you like that some of them are infected. 

I’m about to throw some numbers at you, so if your allergies are bad today just skip a few paragraphs.

Ready? In London, the southwest, the northeast, and the southeast of England, the prevalence of Covid ranged from 0. 08 to 0.02. In England as a whole, it was 0.12%. Using those figures (I’d assume that means the England-wide ones), it would take 16,000 tests to find one infected person. If the tests cost £10 each, that means spending £160,000 to find that one person.

Is that worth it? If we were trying to stamp the disease out and keep it stamped, as New Zealand is, it would be. Given that we treat stamping it out as the silly thought of irresponsible day dreamers, probably not. 

Meanwhile, in leaked emails (I do l love a good leak) “senior government officials” are talking about scaling back mass testing, although the Department of Health and Social Care says it has no plans to end the program. One in three infected people, they remind us, show no symptoms but is still contagious. 

That brings us neatly to the question of whether the rapid tests will spot that one person. In other words, it’s time to talk about false negatives. Administered by an expert, the tests pick up 79% of infections. Or to put that the other way around, they miss 21%, and those are mostly people with a low viral load. Or to put that another way, they’re most likely to miss people who don’t have symptoms, who are just the people the testing program is looking for.

Administered by secondary school students or their three-year-old sisters, they’re more likely to pick up 58% of infections, or to miss–umm– I think that’s 42%. Although estimates of the number of cases the test misses vary. It might be as high as 50%. 

The government denies that it has any plans to scale back anything ever and Boris Johnson is urging everyone to get tested twice a week. Even though his advisors say that in areas with low infection rates, only 2% to 10% of the positive results may be accurate. 

But what the hell, guys, we’ve got these tests. Someone’s cousin has the contract for them. Use them, will you, please? For the good of the nation.

 

News of an accurate rapid test that’s in development

A new test is being developed that’s both fast and accurate. It also tracks variants and tests for other viruses that might be mistaken for Covid. It can screen 96 samples at a time and within 15 minutes it starts to report the samples as negative or positive. In 3 hours, it will have sequenced all its samples. 

It’s also small and portable. It doesn’t make coffee, but it just might be able to make you a cup of tea.

Juan Carlos Izpisua Belmonte, a professor in Salk’s Gene Expression Laboratory where it’s being developed, said, “We can accomplish with one portable test the same thing that others are using two or three different tests, with different machines, to do.”

That’s the good news. But will it go from development to being manufactured and used?

Market analysis would be required to determine whether the initial cost of commercialization—and the constant tweaks to the test needed to make sure it detected new variants or new viruses of interest—are worth it.”

I believe that translates to “maybe.”

It’s called NIRVANA, which doesn’t seem to stand for anything, so I don’t know why it’s in all caps. 

 

High- and low-tech approaches to Covid

In New Zealand, they’re trying out an app that connects to smart watches and fitness trackers, monitoring people’s heart rate and temperature. It’s called an Elarm and the developer claims it can spot 90% of Covid cases up to three days before symptoms appear.

Does that include people who don’t go on to develop symptoms? I’m have to give you a definite maybe on that, because the article I found doesn’t address it. The company’s own website doesn’t answer the question either but says it will also let you know about stress and anxiety, although you might notice those without needing an app. Basically, it figures out your normal levels and lets you know when you’ve wandered off them, so you could end up going into isolation over the flu as easily as over Covid. That would scare the pants off you but would, at least, take a lot of the punch out of flu season.

So how do you use this? New Zealand wants its border force to try it out, since almost the only cases of Covid there are in incoming travelers, who have to go into quarantine, meaning the people who work for the border force are in the front lines.

When New Zealand says quarantine, by the way, they actually mean quarantine. It’s one reason they’ve been able to contain the virus.

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On the other end of the scale comes the recommendation that we open windows in public places to minimize Covid transmission. It’s cheap, it’s simple, and–

Oh, hell, how many public places these days have windows that open? Okay, ventilation. The air in public indoor spaces needs to be replaced or cleaned. 

We’ve heard a lot about keeping two meters (or yards) away from people to avoid contagion, but in addition to the heavier droplets people breathe out, which can carry Covid, the tiniest particles that we breathe out can also carry it, and they can stay suspended in the air for hours. The goal is to run them outside and get some fresh air in. 

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If you’re looking for a low-tech way to decide how far from people you should be standing, you can think of it this way: If you can smell that they’ve had garlic or peanut butter for lunch, you’re too close. 

 

Drug news

An asthma drug, budesonide, has been shown to shorten people’s Covid recovery time –and it can be used at home without anyone involved needing welding gloves, a deep-sea diver’s helmet, or a set of allen wrenches. It’s relatively inexpensive and comes in an inhaler. It shortened people’s recovery time by three days and at the end of two weeks the people who used it were in better shape than the control group.

It’s not clear yet whether it made hospitalization less likely. In the budesonide group, 8.5% were hospitalized. In the control group, that was 10.3%. That sounds like a result, but the problem with interpreting the numbers is that hospitalization rates are dropping in Britain. If you want to understand why that makes the numbers hard to interpret, you need to talk to someone who actually knows something.

Everyone in the test was over 50 and had underlying health problems. The drug can be used in the early stages of infection.