Why Covid is not like Influenza.
I noticed in the JEP this weekend that Dr Muscat made the comment that Covid could become more like seasonal flu over time, although he did caution that he could not say when. It would be something manageable.
The main differences between Covid and influenza which falsify this assumption are as follows:
Influenza is largely seasonal; Covid shows no signs of any seasonality, and while we can expect increased spread in winter months, the recent wave which peaked in July was in summer months.
Influenza is managed by vaccinating the elderly and at risk against the most likely variants, of which there are relatively few. Covid requires vaccination of everyone in the adult population, as the deaths of even fit and younger people has shown, or the prevalence of Long Covid shows. Variants abound and are showing no sign of abating.
And as yet we have no clear knowledge of how long the effects of vaccines last, or whether they will continue to provide enough protection against variants. We already do know that symptomatic Covid is more likely with vaccinated people if they get the Delta variant, but so far the vaccines is still reducing hospitalisation.
Influenza has specific effects and treatments to ameliorate the condition. While some drugs can help in extreme cases, Covid has no medical means of mitigation that is anywhere near as effective.
However, the medical advice reported in BBC Radio 4's More or Less did suggest that we may get to the point where enough people are vaccinated, we can use track and trace to focus much more tightly on sudden flare ups. That's the possible scenario for managing Covid, and it will still mean some self-isolation, contact tracing, but possibly not to the degree we do now.
The Base Rate Fallacy and our Poor Statistics.
The vaccine is not 100% effective, which means that in a population with 100% vaccination, we would still expect to see some spread. So the question then is, given that vaccinated people will catch Covid, how can we tell how effective the vaccine still is.
A classic example of how this works is as follows. Before seat belts became compulsory, a lot of fatal accidents involved people who were not wearing seatbelts, because most people didn't. Once seat belts became compulsory, most fatal accidents involved people who were wearing seatbelt. Unless we know the total population wearing seatbelts, we might be inclined (falsely) to assume that the introduction of compulsory seatbelts was somehow the cause of more accidents with people wearing seatbelts. In fact, it's just a result of the base now being almost 100% seat belt wearing.
It's the same with vaccinations. So to know how effective a vaccine is, and if it is failing or not over time, we need three pieces of information - the total population, the proportion vaccinated, and the breakdown of Covid cases between vaccinated and unvaccinated people.
So if 70% of the population is vaccinated, and say 10 people with vaccinations had Covid, and 10 people with no vaccinations had Covid, the rate among vaccinated people would be 10 out of that 70%, whereas the rate among the 30% would be 10 out of 30%, a much higher figure.
But unless we can differentiated between cases being vaccinated or not, we can't do this, and we can't tell if the vaccine is becoming less effective against variants or over time, or if it is just as effective. Our government statistics still do not provide that information.
The Myth of Covid becoming weaker over time
There's a myth that Covid will become weaker over time, but there's nothing that necessitates that in the evolution of viruses.
The chief metric is the length of incubation, when the virus is hidden but still contagious, something common to all viruses. A virus where symptoms and death occur rapidly can be contained very effectively by quarantine, but one which has a longer duration for infection before it becomes visible will spread very effectively, and will need longer periods of quarantine to contain. This has nothing to do with the ability to kill the host, as if it has a long period of duration, it will have passed to new hosts before the first host has died.
A virus might become less virulent, and if it spread faster, might infect people before the more severe forms of the disease infected them, thus providing immunity, and leading to a weaker virus, but there is nothing to say such a happy state of affairs will happen. In fact, the basis of some vaccinations (not the Covid ones) is to do artificially what the virus will not, and use an attenuated form of the virus to trigger the bodies immune system.
Most notably, Jenner observed that Cow-pox was a weaker variant of the same virus as Smallpox, and by infecting patience with cow-pox, it would give immunity against Smallpox. Hence the name vaccination, after the origins in cow-pox. But it is interest to notice that Cow-Pox was not spreading faster and naturally edging out Smallpox, its more virulent cousin.
Moreover, sometimes the evolutionary story is to do with selective pressure on the population rather than the virus. There is doubt doubt that some viruses of past pandemics largely died out and appeared to become weaker, because those with better natural resistance survived, so giving a gene pool which was more effective at combatting the virus - because most others had died - hence what appeared to be a virus weakening was in fact a story of genetic survival and passing on resistant genes by those lucky enough to survive.
The Myth of Virus as Agency
Human beings have a troublesome habit of giving agency where there is none. Hence we have stories about "the virus trying to overcome the vaccine", as if the virus was like a door to door salesman. What we should say is that the vaccine might prove less effective in countering variants of the virus.
But the variants themselves arise because the virus is an rNA virus, and unlike DNA, rNA is like a replicating machine that is poor at making expect replicas of itself. so that variants appear randomly, without any need for agency on the part of the virus.
And finally...
"The Rock", an antivaccination publication, arrived through my letterbox yesterday. As expected, there was also stuff about the dangers of 5G and the Government conspiracy to control us with vaccines and vaccine passports. Most of it was a UK publication with a local wrapper of the front and back pages. One article also talked about "The Nazification of the NHS", which shows that it is not really a Jersey publication at all, as no one with the slightest sensitivity to the German Occupation of Jersey would let that kind of article through, and anyway we are not part of the NHS.
Pretty well the entire contents are false: there is no such thing as "natural immunity" to Covid, even with children. And the idea that viruses are not pathogens is quite frankly, bizarre. That's by a "biologist" who claims it is all psychosomatic! Of course in the UK, there are a number of communities which may not have seen Covid deaths, so a lot of the presentation that the widespread nature of Covid is false might hold up in the UK, but can't in a smaller community where almost everyone knows someone who has had a Covid death in their family.
Apparently the Real Housewives of Jersey support this publication. I'm sure Hedi Green does, but I'd be interested to know if they all do.
Further Links
https://www.theguardian.com/society/2015/mar/13/measles-sceptic-must-pay-doctor-100000
s
.jpg)
Posts
