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 herd immunity debates

Professors at University College London grabbed some headlines with the news that Britain’s almost achieved herd immunity.

Should we celebrate? 

Nope. The small print said we can’t ease restrictions yet. “If we let up, that threshold will go up again and we will find ourselves below the threshold and it will explode again,” Karl Friston said.

This makes it sound like we’ve probably misunderstood what herd immunity means. Or else that the people who wrote the study have. I thought it marked the point where we could all wander back to whatever we can reconstruct of our normal lives, trusting that the virus will stay in retreat. Apparently not, though–at least not by this definition. 

Irrelevant photo: a rose. Indoors. It’s too early in the year for them outdoors yet.

In a rare moment when the health secretary, Matt Hancock, and I agree (I’m sure that upsets him as much as it does me; sorry Matt; it won’t happen often), he’s dismissed the suggestion of herd immunity, although his comments are oblique enough to be unquotable. They’re not incoherent but they’re not exactly to the point either. Never mind, though. I have agreed with him. It’s a rare moment. We need to mark the occasion.

Cup of tea, anyone?

Another estimate of herd immunity, this one from Airfinity (it “provides real time life science intelligence as a subscription service” and as part of that tracks vaccination programs around the world), sets it at the point where 75% of the population is vaccinated. The U.K.’s expected to reach that point in August, shortly after the U.S. and a few weeks before Europe.

Sorry about the rest of the world. It seems to have dropped off the map the article I found was using. 

There will, of course, still be a need to booster vaccines to keep up with the variants, at least until those countries that fell off the map get access to vaccines so are species can stop producing variants so prolifically. 

 

Creeping out of lockdown

As Covid deaths go down, Britain’s taken another step toward ending its lockdown, opening gyms, shops, pubs and cafes with outdoor seating, assorted other businesses. Internal tourism is causing traffic jams in all the usual places. 

About half the population has at least one dose of a vaccine. Will that be enough to keep the virus from rebounding? I wish I knew. Chile has an impressive vaccination program and unlocked too early, giving the virus the gift of a trampoline. Cases there have spiked. 

Optimist that I am, my mind snags on Britain’s remaining virus hotspots and on the two London boroughs where the government’s chasing cases of the South African variant. I expect they’ll do better with the variant than with the hotspots, because one of the things the government resolutely refuses to do is pay people a workable amount of money to self-isolate, and if you’re broke you’ll go to work, regardless of what the test says. Because you have to. 

On the other hand–and before I go on I should issue an Unimportant Personal Story Warning–I’m grateful to have stores open. I have a battery-operated watch whose battery stopped operating a while ago. (Whose idea was it to run watches on batteries, anyway? I seem to remember winding my watch every day without feeling unduly burdened. I didn’t even break a sweat.) 

How long ago did the battery run out? No idea. We were in lockdown. Who needs a watch? But eventually I did need a watch and I noticed that mine was no longer in touch with consensual reality. So I got a battery (thanks, Tony). I opened up the back (thanks, Ellen), took out the old battery, put in the new one, put the innards back together, and was just starting to congratulate myself when I found that I couldn’t fit the back on, making the whole project pointless. I put a rubber band around the thing and left it alone.

I still didn’t have a watch.

On Monday, the first day that unimportant stores were open, I took it to a jeweler. Jewelers have a little gizmo to hold the back in place while they thump it shut. I now have a working watch.

I don’t need it more than once a week. We’re still halfway locked down. 

So yes, it’s nice to be able to do that sort of small thing. It also makes me nervous–and it should.

 

Lockdown and the economy

Britain’s economy’s now in the worst recession it’s had in 300 years. Worse than the Great Depression of the 1930s? Apparently. To find one that was worse, you have to go back to the great frost of 1709, when Britain was an agricultural country.

On the other hand, having shrunk 9.9%, the economy then grew by 1% in the last quarter of (I believe) 2020. Household savings during the pandemic reached £140 billion–16.3% of people’s disposable income. That’s compared to 6.8% in 2019. Predictably, that’s unevenly distributed, with some people building up savings while others struggle to hold onto their homes and food banks struggle to keep up with need. 

It’s a lovely way to organize a world. 

 

The Covid risk indoors and out

Want to figure out the Covid risk people face indoors? Measure the carbon dioxide level

This works because–well, the thing about infectious people is that they exhale. Admittedly, uninfected people do too. You probably do it yourself. And all that exhaled carbon dioxide joins together and either stays in the room or doesn’t. The Covid virus does exactly the same thing: It either stays in the room or if the room has enough ventilation it wanders out into the world, where it poses next to no danger.

The thing is that carbon dioxide levels can be monitored cheaply. If you see them rise, you still won’t know if anyone infectious is breathing into the mix, but you will know that the ventilation isn’t what it needs to be and it’s a risky place to stand around inhaling. At that point you can (a) limit yourself to exhaling, (b) leave, or (c) improve the ventilation. Preferably (b), since that will help everyone.

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An Irish study reports that roughly one Covid case out of a thousand is caught out of doors. 

Professor Orla Hegarty said, “During Spanish flu people were advised to talk side by side, rather than face to face, and this is borne out by how viral particles have been measured moving in the air when people breath and speak.

“The risk of infection is low outdoors because unless you are up close to someone infected, most of the virus will likely be blown away and diluted in the breeze, like cigarette smoke.”

Herd immunity, sterilizing immunity, and the current best guesses

Britain is now the proud operator of several mass vaccination centers, with more promised shortly, and general practitioners are scheduling their oldest patients for vaccination. But that doesn’t mean we’re out of trouble. The number of hospital cases is still rising and there’s talk of the current lockdown not being tight enough.

And we just approved a third vaccine, Moderna’s. Not long ago, Boris Johnson was crowing at Scotland (which on average isn’t happy about having left the European Union) that if they’d stayed in the EU they wouldn’t have gotten vaccines so quickly. So it’s a nice little piece of irony to read that, approved or not, we won’t get or hands on this third vaccine until April because we’ve left the European Union.

I know I shouldn’t think that’s funny, but I can’t help myself.

 

Irrelevant photo: heather

Are we close to herd immunity?

The latest statistical modeling says one in five people in England may have already had Covid. How did they come up with that number? Since the official statistics inevitably underestimate the number of infections (a big chunk of people don’t get sick but carry the disease without knowing it or showing up in the statistics) and since the track and trace system is widely recognized as being roughly as useless as it is expensive, they get their statistics by comparing the number of deaths in an area to the estimated infection rate, putting them in a blender with a few other number and a dash of cinnamon, then baking at 160 C. for fifty minutes. 

In some areas, they estimate that one person in two has had the disease. The number of infected people may be up to five times higher than the number on the test and trace books.

Is that herd immunity? 

Nope. Exactly how many people would have to have had the bug to create herd immunity is still unknown, but a computational biologist estimates that 70% of the population will need to be vaccinated to stop the pandemic in the US. But that only applies to the US; it’s not a fixed number. People behave differently in different places, which upsets the numbers–they’re touchy little beasts–so they arrange themselves into different patterns. 

The number also depends on how long immunity lasts–no one knows yet–and on whether the vaccine turns out to keep people from passing on the infection. 

Most of our commonly used vaccines prevent severe illness but don’t give us what’s called sterilizing immunity. In other words, they keep us from getting sick–or at least from getting very sick–but they don’t kill off every bit of the disease that’s running around inside us. 

On the positive side, having less of the disease circulating inside our complicated little innards may (notice how much wiggle room I’ve left myself there) mean we pass on a milder form of the disease if we do give it to someone else.

An experiment with a chicken virus and a flock that was half vaccinated found that the unvaccinated birds came down with a milder disease than if the whole flock had been left unvaccinated. So even if the current vaccines don’t give us sterilizing immunity, Covid may yet follow that pattern and become milder once a significant portion of our flock has been vaccinated.

May. No one’s offering us a guarantee.

And no, none of the vaccines currently in use will cause us to grow feathers.

 

Transmission and hospitalization

In Britain, the current crop of hospitalized Covid patients are younger than they were during the first peak of the virus. People under 65 now make up 39% of hospital admissions. In March that was 36%. It’s not a huge change, but it is a change, and it’s worth noticing. 

The best guess is that the over 65s are more likely to be out of circulation. We left the party early and are tucked up in our little beds just now. That makes us less likely to become infected and less likely to show up in either the hospital or the statistics. But so much emphasis has been put on the elderly being vulnerable that we tend to think the non-elderly are made of steel.

They’re not. They can get very sick from this thing. In particular, pregnant women seem to be more vulnerable than non-pregnant women (or non-pregnant men, for that matter) in their age groups. 

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Half of all Covid transmissions come from people with no symptoms, including from people who never do develop symptoms. 

What does that mean in practice? That every one of us needs to act as if we could be carrying it. And that we need to look at our friends and family and neighbors as if they could be carrying it. That we need to look at other human beings and think, Oooh, yuck, germs! 

That’s not, I admit, a policy recommendation. It’s not even a real recommendation. It’s just an observation on how much it goes against the grain to live this way.

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A study reports that Covid can still be transmitted after seven days. Or after ten days. After ten days, 76% of the people tested still had detectable levels and 86% did after seven. 

So recommending a shorter period of isolation is a gamble. On the one hand, the theory goes that people are more likely to actually isolate themselves if you demand a shorter time. On the other hand, they can still be shedding the virus at the end of it.

The problem is not only that some people are jerks and don’t put the safety of others first. The larger problem is that a lot of people can’t afford to miss a day’s work–they’re living on the edge as it is. So when mass testing’s offered, they don’t show up because they can’t afford to be told to stay home. If they do end up getting tested and are positive, they stagger to work for as long as they can anyway. Because the hounds of hell are nipping at their heels. 

Already 70,000 households have become homeless during the pandemic and some 200,000 are teetering on the edge. There’s money available to people who have to self-isolate, but not to everyone and it’s not enough to cover the bills anyway. 

And if that doesn’t hold your attention, some people are still being told they’ll be fired if they don’t come to work.

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On a happier note, my partner’s been scheduled for her first vaccination. If all goes well (stop laughing–it could) I should be in line in mid-February. 

Moles, pizza, and remdesivir: It’s the pandemic news from Britain

A local spike in coronavirus cases in Leicester has been handled with all the grace and efficiency we expect of our government. It announced a local lockdown. The health secretary said the police would enforce it as needed. The message was, we’re tough. We’re efficient. We’re gonna win this thing.

The local police and crime commissioner still didn’t know where he was supposed to enforce the lockdown, though, because he hadn’t been sent a map. Then he got a map but still didn’t know the details of what they were supposed to enforce. 

But it’s okay, because we have a prime minister who can do at least one pushup while keeping two yards away from a photographer.

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Irrelevant photo: St. Nectan’s Kieve

Chaand Nagpaul, from the British Medical Association, said Prime Minister Boris Johnson’s strategy of dealing with local outbreaks will be no use if the local people who are expected to contain them aren’t given the data they need. 

I could have said that, but it sounds better coming from someone with a medical degree. Leicester could’ve responded earlier if they’d been told they had a problem, and where and how and why.

When Johnson introduced his strategy of containing local outbreaks, he described it as whack-a-mole–a game where you whack a plastic mole with a plastic hammer and even if you’re fast enough to hit it, it pops up out of another hole. 

It was a rare moment of honesty in political discourse.

While we wait to see where the mole’s going to pop up next, Johnson tells us that local authorities have been sent the data they need. 

And the check is in the mail.

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You’ve probably heard by now that the U.S. bought up almost the entire stock of remdesivir–500,000 doses: 100% of the manufacturer’s July production, 90% of August’s and 90% of September’s.

Remdesivir cuts Covid-19 recovery times, although it’s not clear whether it improves survival rates. Other counties have pointed out that buying up almost the entire stock might, um, undercut international cooperation in the face of the pandemic. 

“International what?” Donald Trump replied. 

Okay, he didn’t actually say that. I can’t remember ever seeing a quote in which he asks a question. 

The sale makes it sound like other countries are thoroughly screwed, but in fact they should be able to get the drug via compulsory license, which allows countries to override patents and buy generic versions from countries where the patent isn’t registered. This one is widely registered, but there will, it seems, be gaps.

The drug is made by Gilead, which sounds like it escaped from The Handmaid’s Tale. I’d love to tell you that it didn’t, but I don’t really know that. Lots of things have escaped from fiction lately, and nothing is more bizarre than reality. 

The UK’s Department of Health and Social Care tells us it’ll be fine and it has enough remdesivir “to treat every patient who needs the drug.” 

For how long?

They didn’t say.

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The New Scientist says, “There is no longer any serious doubt that our bodies can form an immune memory to the SARS-CoV-2 virus.” 

The bad news is that we still don’t know how effective that memory will be. In other words, we don’t know if an immune memory’s the same thing as immunity.

Don’t you just love to hear from me? Don’t I just lift your spirits?

And from the Department of Confusing Information comes this snippet: For every person testing positive for Covid-19 antibodies, two more turn out to have specific T-cells that identify and destroy Covid-infected cells. That’s true even in people who had asymptomatic cases or mild ones.

What does that mean in everyday English? It means that for every person who registers positive on an antibody test, two more have some sort of immune response that doesn’t register. 

Those T-cells the two people have might give them some immunity to the disease. They might keep them from passing the disease on to other people.

They also might not.

The reason T-cells don’t register on an antibody test is antibodies are a whole ‘nother part of the immune system. Expecting to notice T-cells on an antibody test is like making yourself a pizza and wondering why it doesn’t come out of the oven with a side salad.

Basically, antibodies–that’s the pizza–attack the virus before it enters the body’s cells. T-cells–they’re  the salad, and it’s important to remember which is which–go into action once cells have been infected, attacking  them so they won’t infect  new ones. A balanced immune system meal needs both pizza and that salad.

You’re welcome. I’m here to clarify every baffling bit of our world, just for you.

What does all that mean for herd immunity? Not much, because for all anyone knows at this point, those T-cells could protect the bearer without keeping him or her from passing the virus on. 

If you worked this many twists into a pandemic movie, I’d throw my popcorn at the screen and stomp out, muttering, “Enough already.” 

Then I’d go out for pizza and a salad.

I’m just about old enough to remember a world where it was safe to go to movies and pizza joints.