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. 


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.


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.


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. 

64 thoughts on “Herd immunity, sterilizing immunity, and the current best guesses

  1. A optimistic article with reference to how our immune system might deal with things post-vaccination here for you: https://theconversation.com/covid-19-immunity-how-long-does-it-last-152849
    Good news for Ida and everyone else… so far.
    Thankfully no further development or escalation of symptoms for either Mrs S (tested positive 3rd Jan, results and isolate for 10 days email on 4th) or myself (tested negative same day, told to isolate by 5th Jan email message until the… 5th Jan!)

    Liked by 1 person

    • Told to isolate from Jan. 5 to Jan. 5? They do play hardball, don’t they? I’m grateful you’re both seeing no change. All fingers crossed. Now I’ll go look at the good news and feel my mood lift even further. Thanks.

      Liked by 1 person

      • Yep, difficult to have any trust in the system at all really. Mrs S just had a messenger conversation with a friend upcountry. She told her that she had booked a test but didn’t end up going as she got so anxious about doing it. Two days later she got an email telling her she’d tested positive.

        Anyway, good luck to everyone currently trying to survive in Great Plague Islands.

        Liked by 1 person

  2. Gosh, didn’t know about Steriling immunity and the chicken experiment. Surprised they knew of a mild chicken virus. Often the first sign of illness in chickens is a dead chicken…..

    Did you know that poultry have thier own pandemic? Our girls are in lockdown too!

    When I watch TV films/dramas and see crowds, it feels so strange. Oh look, in the olden days we used to get close to people.

    Hubbys parents get thier first vaccine tommorrow. To avoid them taking a bus (in London!) we are driving 50 miles to get them to the appointment. Hubbys sister lives closer, but has symptoms and is awaiting test results.

    Am I wittering? Very probably. Its getting lonley in Berkshire

    Liked by 3 people

    • You’re not wittering at all–it’s all highly relevant. That’s sobering about what it takes to get your in-laws to the vaccine. What on earth do people do who don’t have anyone they can rely on? It’s easy to get complacent where I live, with plenty of space around us and a car parked out front.

      I had heard about the chickie-demic, but then it dropped out of the news, as so many things do, and I forgot about it. I didn’t realize it was still going on.

      Liked by 1 person

  3. It’s positive news that your partner has been scheduled for her vaccination… going by the research, that means if you contract the disease it will be milder, statistically speaking.. excuse my poor joke. My brother in law got his vaccination too a couple of weeks ago as he is a pharmacist. Many people are suspicious of the vaccine but historically speaking, vaccines have proven very effective at stopping people from dying of horrid illnesses so I try to remind myself of that. When you say 70,000 households have become homeless since the pandemic… wow that really puts it into perspective doesn’t it. I keep thinking how cold it is outside and how children need warmth and stability. I don’t blame people for going out to work despite having symptoms. What else can they do? Honestly? It might be called selfish but is it selfish to need to feed your kids or keep your job? It’s a tough situation to be in and I wouldn’t wish it on my worse enemy. Thank you for continuing to keep us updated with your humorous input, Ellen. I really enjoy these posts. News outlets should hire you, you tell the news but also keep it entertaining… we need that in a pandemic haha.

    Liked by 4 people

    • Thanks for that. I was afraid I hadn’t gotten enough baking powder into the mix this time and it would be heavy and depressing. Hence the addition of chicken feathers. Speaking of which, I was just listening to Women’s Hour on Radio 4 and apparently there’s a rumor going around that getting vaccinated might interfere with a person getting pregnant. Assuming, of course, that the person in question is female, in the right age group, and doing the things that make pregnancy possible. They had a couple of experts on to say there was no evidence whatsoever to indicate that, but rumor’s a powerful force.

      Liked by 2 people

      • Oh I heard that rumour too! I had a debate about it because when I read the actual study it said it was unknown whether the vaccine caused infertility in women, but people kept saying that meant it DID. No it doesn’t! It means they haven’t had any tests or indications of that (and it is still early days). But rumour is a very powerful force indeed because I have a whole whatsapp group of angry females telling each other not to get the vaccine because it will render them permanently childless. Who knows!

        Liked by 1 person

  4. I think younger people are just in circulation more. They need (or needed, until schools were closed) to take kids to and from school, and they need to go to work. I’m working from home, but I need to go into the office at least once a week to return files I’ve finished with, collect files I need, leave things that need input from colleagues, collect the post (the alternative being to give clients my home address, which I’m not comfortable with doing), etc.

    Liked by 3 people

    • Very true. It really makes me question the vaccination priorities. At the top of the list should be the people who can’t withdraw from the world. I’ll be grateful to get the vaccine and I won’t turn it down, but I don’t think I should be as high a priority as I am.

      Liked by 2 people

      • They’re trying to vaccinate the higher risk groups. All countries seem to be doing the same, so presumably that’s what the experts thing best – it was raised at this evening’s press conference. I assume that, once they’ve done all the high risk groups, people like police officers will come next.

        Liked by 1 person

        • Given how close to–or past–most countries are to overwhelming their health systems, it seems to make sense that health care workers should be first. It’s like the adult putting the oxygen mask on themselves first if a plane’s in trouble before putting it on a kid. It goes against all our instincts, but they need to be functional before they can help anyone else.

          I’m sure there are many ways to calculate vulnerability, but having to leave the house and work with the public is surely one of the things that needs to be weighed.


    • Eliminated them both or made introducing them look like a good idea to most kids–if not to the parents or teachers, necessarily.

      I’ll put your suggestion into the epidemiologists’ suggestion box and the next opportunity.

      Liked by 1 person

  5. You forgot to mention that the virus can mutate at any time! What happens then, no one knows? The virus will fight to survive and probably mutate into a vaccine resistant form or a form that can infect people who have already had the virus. This is disturbing. It could also mutate into a more deadly version, resistant to the current treatments. I still believe that the only answer is passive prevention. Yes, the vaccine will save lives but it will not stop the virus. Vaccines are an active measure requiring people to do something that many do not want to do, just like masks, washing hands and social distancing. These are active measures. Passive measures are things such as public areas being disinfected either by chemical means are more preferably by using UVC lights, both UVC and the more safe far UVC lights, I think are the best option. These require no public compliance, just and electrician or persons to screw in a light bulb!

    Liked by 3 people

    • It will mutate, possibly in a deadlier direction, possibly in a less deadly one. And possibly in a way that will need vaccines to be tweaked. From what I’ve read, the vaccines will continue to be tweakable. If large-scale sterilization turns out to be possible, great. But if not, I don’t think all is lost.

      Liked by 1 person

  6. I’ve always believed a joke or two couldn’t really be too harmful when writing about pandemics – so full speed ahead. What the hell, my personal humor threshhold has reached a new low in the last week – tickle me, Elmo, er…Ellen.
    SC Guvner Henry McMaster (who looks and talks like he recently stepped off a Confederate war memorial) announced yesterday statistics seemed to indicate more old people died from the virus than young people (which was breaking news to him) so he was officially proclaiming South Carolinians over the age of 70 eligible to sign up for appointments for vaccines Wednesday, the 13th. of January.
    Do not make the mistake of trying to find out where or how to do that yet because nothing is available, says the Voice of Authority.
    I will keep you posted. Glad Ida has been scheduled!
    If all goes well and again, why wouldn’t it?, Pretty should be in line at a later date tbd by the same guv. BTW, our DHEC director resigned last week. Hm. Resignations everywhere, and not a Trump to be found.

    Liked by 3 people

  7. All the best for your partner. Another informative post. Wow the homeless figure!!

    I just don’t know what to say. Boris, lost the plot in November, and ….. But, I am told it is hard to be a prime minister. I can see it is hard. But, other countries got it right. Was he trying to herd us?

    I agree we have a good few j…ks that just don’t social distance or believe it exists, even after they got it. Ahhhhhh

    I like your dash of cinnamon recipe.

    Ahhhhh. May be i should watch danger mouse: unrelated lol. 🤪🥴😃🙃😉

    Liked by 3 people

  8. If I was a billionaire, I’d fly all my blogoverse friends to Australia for some R&R, sunshine and a dose of sanity, using the ‘compassionate and compelling reason to travel’ exemption. The only drawbacks to this plan are that I’m not a billionaire and (mostly) sensible people get to decide about exemptions. I say ‘mostly’ because it appears that we’ve just discovered that aircrew on the few flights coming in might bring the plague with them. Imagine that.

    Liked by 1 person

    • It’s a generous impulse, but you really, really don’t want us there. And I don’t want to be in a sealed tin can, flying above the ocean, with a bunch of other people with the odd habit of exhaling.

      But setting that aside, it’s a great idea. Thanks.

      Liked by 1 person

  9. Dr, Jenner somehow connected the fact that milk maids who’s had cowpox were less likely to get smallpox, or had milder cases. I wonder of there’s some analogy here ?

    In last Wednesday’s unpleasantness at The U.S. Capitol members of the House of Representatives were sheltered together for some hours in a large room. Some members of the GOP were not wearing masks and refused to wear them when they were offered. Now three members (Dems of course) have tested positive for Covid, including one woman in her 60’s who is a cancer survivor. As we used to say when I was in high school “Smooth move, Ex-Lax !”

    Liked by 1 person

      • I just saw an interview with a 77year old congresswoman who got covid during the capital invasion. She is a cancer survivor, and what is more shocking is that a few weeks ago she received her first shot of the vaccine! Yes, even if you have the vaccine you can still get covid. She only has mild symptoms but also received monoclonal antibody treatment. The vaccine might have saved her life and reduced her symptoms but it did not prevent her from getting covid! The vaccine will not stop the spread of covid. What is worse is that the vaccine might increase the amount of asymptomatic carriers of covid since the vaccine reduces the severity of the disease but does not protect from getting covid. This is no reason to not get the vaccine because it can save your life no matter what age you are and at what risk level you are. Far UVC light disinfection is the only answer to killing the spread of the virus in my opinion.

        Liked by 4 people

        • Whether people who’ve been vaccinated will be carriers remains an unknown–possible but not yet proven. We’ll see. The congresswoman might not, after a couple of weeks, have reached the full immunity the vaccine confers, although I don’t, off hand, remember how long that takes for which of the vaccines. But yes, absolutely, it can and does prevent the most serious effects of the virus. Which she caught because some of the idiots who get themselves elected have confused not wearing a mask with individual rights instead of homicidal carelessness.

          Liked by 3 people

        • Yes – that is the woman I was referring to -I couldn’t remember her name so I could verify her age. Both the others – a man and a woman (so far) have given interviews where they expressed their anger.

          Liked by 2 people

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