Cycling UK Forum

horizon wrote:

Jdsk wrote: And it also applies to engineered vaccines in the two other classes of interest: DNA-based and the Oxford type of viral-vectored. And the production, testing and authorisation of each new version could be quicker than the first, and that was stunningly fast.

Would that also mean vaccinating again those people who had already had the first vaccine? Or would their vaccine cover the newer ones?

Could work out either way, and could differ between existing vaccines.

Even without viral mutations there's lots that isn't yet known about the immune system reaction to the vaccines, including duration of protection.

Jonathan

Once thing if for sure, I'm going up take it. My lungs are weak so I'm afraid I'll die if I catch the disease. I'm — however — currently residing outside of the UK and over here we'll not get it (only the elder, so far, which IMHO is fully legit) until sometimes in the first or even second quarter of 2021.

Even without viral mutations there's lots that isn't yet known about the immune system reaction to the vaccines, including duration of protection.

How will that pan out? What is the mecahnism of the virus coming & going? Is it possible that the virus goes into hiding until the effects of the first vaccination wave wear off and then pops up again? Or are we hoping that the removal of a large number of people from the pool of available hosts means that the virus gives up and goes away? Or are we saying that, at this early stage, we just don't know?
(As usual, I'm not expecting a thorough answer - just point me in the direction of a good article...)

I'll try and find something about how this might pan out.

In the meantime a few thoughts:

1 After the pandemic in the medium term it's likely that there will be a phase of repeated local outbreaks. The recent experience in the UK is not a good guide to how these can be managed: we simply haven't seen rapid control of outbreaks. Testing, tracing and isolating (and RSN vaccination) can work very well.

2 Have a look at how humans are affected by some other communicable diseases, viral and other. Smallpox, rabies, HIV, influenza, cholera, plague, diphtheria illustrate different elements of control.

3 Ignore anything claiming that the virus will inevitably become more or less transmissible or more or less deadly. There are different patterns but they work rather better in hindsight...

4 What are the hosts going to be? This is why the minks in Denmark were so worrying... as in your question about "hiding".

5 Medical science and technology has worked extremely well and is only going to get better. That's been the case for detection and identification and vaccination, and there's a lot more to come on treatment. There's some xenophobic stuff somewhere about the new variant: it's very misleading to suggest that new variants aren't being identified wherever they occur and the findings rapidly shared. On treatment the excellent work showing benefit of steroids was totally dependent on an evidence-based approach. That happened to be a traditional drug but the same approach will probably identify novel immune modulators and other stuff that works.

Jonathan

simonineaston wrote:

Even without viral mutations there's lots that isn't yet known about the immune system reaction to the vaccines, including duration of protection.

How will that pan out? What is the mecahnism of the virus coming & going? Is it possible that the virus goes into hiding until the effects of the first vaccination wave wear off and then pops up again? Or are we hoping that the removal of a large number of people from the pool of available hosts means that the virus gives up and goes away? Or are we saying that, at this early stage, we just don't know?
(As usual, I'm not expecting a thorough answer - just point me in the direction of a good article...)

(My understanding) You are asking about "Herd Immunity". As more of the population have immunity from a disease so it gets harder for the virus to come across somebody it can infect e.g. If a person has the virus but never meets anybody who is not immune, that infection is stopped/closed off. The more of a population is immune, fewer infected people are able to pass their infection on to others.

As more and more people become immune so the virus spread is more and more contained/restricted as it is not being passed to people who can host an infection (and the virus needs to infect a new people, replicate and spread on to more people, etc.).

The result of this is the disease becomes contained or even eradicated. To eradicate the virus herd immunity has to be maintained for a fair time.

So the virus does not "give-up" and "go away", just infections are not being passed on.

The level of population immunity (through infection or vaccination) varies depending on the disease characteristics e.g. measles needs above 90% of the population to have immunity, Ebola 40%. For C-19 estimates of immunity levels needed for herd immunity are uncertain and changing but current thoughts seem around 60%-80%. Also I've not seen how the UK version Mutant ninja virus is going to impact the population immunity levels necessary to achieve herd immunity.

But is gets more complex as herd immunity also presents an "Evolutionary Pressure" on some virus in effect "encouraging" new strains to form.

Ian

It's not quite what I was looking for, but here are some projections from a strongly immunological point of view:

"Immune life history, vaccination, and the dynamics of SARS-CoV-2 over the next 5 years"
https://science.sciencemag.org/content/370/6518/811

"Imperfect future immunity
Humans are infected by several seasonal and cross-reacting coronaviruses. None provokes fully protective immunity, and repeat infections are the norm. Vaccines tend to be less efficient than natural infections at provoking immunity, and there are risks of adverse cross-reactions. Saad-Roy et al. used a series of simple models for a variety of immune scenarios to envisage immunological futures for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) with and without vaccines. The model outcomes show that our imperfect knowledge about the imperfect coronavirus immune landscape can give rise to diverging scenarios ranging from recurring severe epidemics to elimination. It is critical that we accurately characterize immune responses to SARS-CoV-2 for translation into managing disease control."

Jonathan

Hmmm - any chance of an animated graphic? No seriously, Jonathan's link is just the job

simonineaston wrote:Hmmm - any chance of an animated graphic? No seriously...

Yes, as the article includes:

The dynamic impact of these and other parameter variations can be explored interactively at https://grenfelllab.princeton.edu/sarscov2dynamicsplots. For example, strategies to suppress future outbreaks [e.g., (56)] could be simulated by increasing the duration and strength of NPIs, then exploring optimal vaccine deployment as vaccines are developed and rolled out. See (37) for a full discussion of all caveats and future directions.

That really is an animated graphic!

: - )

Jonathan

Yup - I spotted that! What a wunderful digital world we live in

It's been a big year for infographics!

Jonathan

Don't know much about these things so the following may be a load of tosh. From what I understand a virus just wants to reproduce itself and needs a host for that. If the effect on the host is grave mankind tries to do all it can to eliminate the virus and it's effects. I believe a virus can frequently mutate so isn't it likely to mutate into a minimally harmful form that will not have a great arsenal of medical treatment aimed at eliminating it?

pete75 wrote:From what I understand a virus just wants to reproduce itself and needs a host for that

I know what you mean, but you've probably reached a point in the explanation where "wants to" and similar might not be helpful. Yes, the virus needs a host, and it gets a lot more complex if there's more than one: see the origin of SARS-CoV-2 and the concern about minks.

pete75 wrote:If the effect on the host is grave mankind tries to do all it can to eliminate the virus and it's effects.

Do you mean with immune reactions and similar (which have been around for millions of years) or with public health procedures (possibly thousands of years) and medical interventions (mostly a few hundred years)?

pete75 wrote:I believe a virus can frequently mutate so isn't it likely to mutate into a minimally harmful form that will not have a great arsenal of medical treatment aimed at eliminating it?

A lot is now known about mechanisms of mutation. Rates of mutation vary a lot between different types of virus, and aren't particularly high in coronaviruses compared to eg the viruses that cause influenza in humans.
But I wouldn't predict any directions of travel in properties such as transmissibility or pathogenicity for any given virus at any given time. Some patterns can be seen with the benefit of hindsight.
And as with "wants to" the virus (or strictly speaking its replicators) can't aim for a future that avoids medical interventions that oppose its survival. But it can get there through natural selection.

Jonathan

pete75 wrote:I believe a virus can frequently mutate so isn't it likely to mutate into a minimally harmful form that will not have a great arsenal of medical treatment aimed at eliminating it?

I assume you mean evolve rather than mutate. Mutations are random whereas evolution is directed by natural selection (as Jdsk says).
It doesn’t seem inevitable that the direction will be towards lower virulence. I imagine higher transmissibility could combine with higher virulence, after all only a very small fraction of people die of it and apparently 10% of infected people are responsible for 80% of infections.

It’s complicated, obviously.

pwa wrote:Blair (remember him?) is saying a single dose gives 90% immunity and that we should be giving that single dose to as many vulnerable and care / health sector people as possible before thinking about second doses. That does make some sense.

It appears they are going to do exactly what Blair suggested. Yet the amount of grief he got on here and other social media

The government said the vaccine rollout will change slightly to focus on giving as many at-risk people as possible the initial vaccine dose.

People receiving the Oxford vaccine or the one from Pfizer/BioNTech, which is also being rolled out, will now receive their first dose of the vaccine followed by a second dose up to 12 weeks later.

https://news.sky.com/story/covid-19-oxf ... k-12155958

Another interesting point that supports the one jab (initially) theory in relation to the Oxford vaccine

However, unpublished data suggests that leaving a longer gap between the first and second doses increases the overall effectiveness of the jab.

https://www.bbc.co.uk/news/health-55280671