Why Covid-19 affects some and not others – maybe

One of the things that has puzzled a lot of people about the Covid-19 is why it affects some people very severely – even to death – and yet others can be completely asymptomatic and not even know they had it. This very wide range of possible severity has fuelled a good deal of ill-informed assertion in social media, usually as part of an argument denying the virus is a problem, so let’s get back to normal life.

Needless to say – but I’ll say it anyway – the fact that the virus doesn’t appear to affect some people is no reason to belittle it. The fact is it kills. And one death is one too many. Those who belittle it, of course, always think ‘it won’t be me’. But what if they catch it? There have been a few cases of this kind of schadenfreude and, sadly, also deaths. But there is also evidence building up that even those who shake it off – who may not even know they had it – can suffer longer-term damage to major organs.

The real question, of course, is why the virus is so variable in its effects. What’s going on? As it’s a new virus, nobody quite knows yet – but there was some interesting research published last week in Science, from the La Jolla Institute for Immunology in California. Click through to check it out. The basic gen, though, is that Covid-19 is a coronavirus, part of a large family of similar viruses that include those causing the common cold. All are quite different, of course. But according to this report, immune system T-cell ‘memory’ of having had one of four varieties of the common cold could alter the way the immune system responds to Covid-19.

The way it is theorised to work is this: the common cold and Covid-19 are different viruses, but similar enough that the immune system has a ‘head start’ when fighting it off. It’s early days yet, and nothing is proven. Indeed, the theory has been described as speculative. But it’s interesting, and it might explain why some people become very sick while others are scarcely affected.

I am prepared to bet, though, that it won’t be a magic bullet for the pandemic. This is a brand new virus and we’re only in the early stages of understanding it. Thoughts?

Copyright © Matthew Wright 2020

12 thoughts on “Why Covid-19 affects some and not others – maybe

  1. I saw some analysis the other day that sort of matched my suspicions on how this will progress, which somewhat ties into what you have noted.

    I don’t think we’re going to get a magic bullet, so to speak, in the form of a vaccine that wipes the virus out, such as we have for smallpox. Rather, I think we’ll develop a vaccine withing the next couple of months, but what we’ll achieve with that is a sort of soft immunity. This family of viruses evolves fairly quickly and it’ll out run our ability to actually get ahead of it and destroy it completely. in order to do that, we would have had to have a vaccine months ago. The fact that we’ve now had a few people who have reacquired an evolved variant of it shows that.

    What it also shows is that as it spreads and eventually becomes nearly universal, it’ll be a less dangerous disease. That’s in part because some will have had closely related viruses, some will have had a version of it and acquire near immunity that way, and then finally the variants of the disease itself will evolve to be less dangerous as killing your host is a bad evolutionary strategy.

    Liked by 2 people

    1. Yes, I doubt there’ll be a magic bullet for Covid-19 either. Or a quick fix. And as you say, it’s evolving – perhaps less quickly than the flu virus, but it’ll still do it. The issue of diseases waning over time will hopefully help – though, history tells me, it took about 300 years for the Black Death to actually dwindle. Ouch. But hopefully Covid-19 will be less virulent in that sense.


  2. Mmm…bit of a worry coz I can’t remember the last time I had a cold. Does that mean I’d be one of the unlucky ones who get the severe version of the disease? I hope not. :/

    Liked by 1 person

    1. Yeah I last had a cold years ago, same concern. My understanding, though, is that the interaction could also backfire, ie: it might make things worse – lots of research yet to be done. But interesting. To me it shows up the fact that this is a new disease and the science has only just begun what will likely be a years-long study. And it has to be years, because it’ll take that long for the full outcomes to become evident.

      Liked by 1 person

      1. At this point I just hope that someone comes up with an effective vaccine, and that we have access to it. Not sure what the NZ govt is doing re signing up to vaccines, but Australia has been…slow. We have one, maybe.

        Liked by 1 person

  3. As a non scientist, my view is that any vaccine will be somewhat akin to the flue vaccine. You can gain some protection from flu by vaccination (and it particularly useful for those with underlying health conditions and the elderly to be vaccinated), but the flue vaccine does not offer total protection. So a COVID vaccine may well offer some protection, but not total emmunity. On a separate though related point, while I agree we should certainly not make light of the virus, we also need to be extremely careful that we don’t harm civil liberties when responding to it. Banning people from different households from mixing would (until recently) be something which one would associate with Fascist or Communist governments. But such policies have been implemented by democracies such as the UK and anyone who cares about liberty should be deeply concerned that democratic governments have resorted to such action. Kevin

    Liked by 1 person

    1. Here in New Zealand, with the exception of some minor specific adjustments that had to be legislated, all government actions to date have been within the powers already available through the Health Act 1956. That includes the power to limit gatherings and to issue enforceable orders against individuals. I agree that care is necessary not to permanently reduce civil liberties. But equally, in circumstance of national and social emergency such as Covid-19 presents, the needs of the many must outweigh those of the few. That reverses the attitude of the last thirty-odd years in the west, where the few have always been promoted over the many. But to me, it’s acceptable to have short-term constraints in order to achieve longer-term freedoms. The alternative, unfortunately, appears to be an unknown risk of death and/or longer-term disabilities for those who contract the virus. As yet still unfolding to science. In such circumstance, caution seems to be indicated. The crucial issue is making sure that whatever constraints are imposed are then lifted when the emergency is over.

      Liked by 1 person

      1. I (albeit reluctantly) accept the need for some restrictions on mass gatherings. However I think that when (as in the UK) couples (who where not already living together) where instructed not to meet indoors, that this was a step to far. Extreme collectivism and extreme individualism are both dangerous. But my instincts are for individual liberty over collectivism. Best. Kevin

        Liked by 1 person

  4. Matthew that’s interesting and thanks for this, I’d not come across it before. There may be something else at play which is the mutations to new strains which are documented. As mentioned in a comment above, killing your host is a bad evolutionary strategy, but it is strange to look at the huge variation in mortality numbers per million acoross the globe. New York has a little over half the cases of California but nearly three times the mortality number which may be down to an earlier strain of the virus. But maybe T-cell memory is also distinct for different populations, hopefully we will find out. Thirty new cases reported in Devon today, we’re on our second wave.

    Liked by 1 person

    1. Yes, there seem to be huge variations – often, I suspect, from subtle mixes of forces: shifts in the virus itself are among them but I wonder about other factors. Of course it’s early days yet, in a scientific sense, and I expect it will get unravelled. One side outcome, I suspect, will be a huge raft of new science about how viruses and immune systems work generally.

      Here in NZ we’ve also had a second wave, which has been stomped on. They’ve had time to ramp up contact tracing and control systems, so the lockdowns haven’t been as severe. It’s been interesting. NZ has long been really, really good at biosecurity and limiting the way disease spreads in the plant and animal population. They stamped out micoplasma bovis in the cattle population – first and only time it’s been done in the world. All the government has done is apply those same methods to the human population, with a couple of exceptions in technique because, hey, it’s humans. And it’s worked. Being an island nation has been part of the mix but a good deal of it is down to applying some well-honed techniques.

      Liked by 2 people

      1. “One side outcome, I suspect, will be a huge raft of new science about how viruses and immune systems work generally.”

        Indeed, not only do I agree with you, but given the vast amount of information that’s been learned about viruses due to AIDS, and which is now being learned about them due to COVID-19, a disease closely related to the common cold, my prediction is that this will be the last great pandemic ever.

        Pandemics and Epidemics have been with us since day one, and will continue to be to some extent, but at this point, I think we’re likely on the threshold of being able to defeat diseases of this type and this event will be the last of its kind.

        Liked by 1 person

        1. Without wishing to appear a bit of a sourpus, I wonder if we will get a Covid vaccine ever. Firstly there isn’t one for the common cold and secondly there was never one found for SARS 1 or MERS. Coronaviruses seem to be very wiley customers, but who knows?

          Liked by 1 person

Comments are closed.