From the article below:
Government advisers have warned ministers they believe the new variant of COVID-19 spreads more quickly than previous strains, and that relaxations in public attitudes risk offsetting the benefits of the vaccination rollout over the course of the coming months, Sky News understands.
The issues is that if proven true, infections could increase much more dramatically and overwhelm health services.
Also - we don’t know if this is confined to the UK alone, or one region in the UK - the reaction by UK government by putting Londin and nearby regions into a new Level 4 rectriction appears to reinforce a view that this is a regional matter for now - however London has special conditions anyway, it is by far the most internationally connected city in the UK, plus it is densely packed in places and has an extremely dense transport system in the form of the underground. Other UK cities have some similar aspects but nothing like to a similar level of intensity.
We will have to see if this has come in from elsewhere, perhaps from other EU nations where there has been a worrying increase of infections, or if it is a UK version, and also what impact it must necassarily have on international travel.
Wouldn’t the expected evolutionary trend be for easier spread and less severe disease?
Really, the only fundamental trend is for easier spread. That’s the characteristic that’s under direct selection.
Natural selection will favor less severe disease only indirectly, if the course of disease implies easier spread. Typically, if a more severe mutant strain debilitates you so quickly and completely that you are physically no longer able to move around and encounter other human beings, that strain will not survive. But if another severe mutant strain leads to a course of disease with gradual onset, allowing you to live normally in a highly infectious state for several weeks before you get any serious symptoms, before slowly but inexorably killing you, that strain may proliferate.
Fortunately, it’s obviously generally going to be true that more serious symptoms and increased mortality tend to be associated with more rapidly debilitating symptoms that decrease contact with other humans, thus lowering transmission. But that’s not necessarily so.
ETA:
And there’s no reason that easier spread will always go hand in hand with less severe disease. Giving humans less severe symptoms so they can keep walking around to spread the disease to more other humans is only one possible way for a mutant strain to increase transmission.
I would say its as scary as it sounds.
Not that we ever needed more cases we certainly don’t need them now.
That’s what often happens, yes. But there is no guarantee that any given virus will play by our expectations.
That’s what often happens, yes. But there is no guarantee that any given virus will play by our expectations.
But it is absolutely guaranteed that natural selection will prevail.
Of course, the trains out of London have been packed this weekend as people scramble to join up with family for Christmas before tier 4 comes into affect 
People probably also tearing up the motorways to get somewhere else before they run out of petrol.
A growing list of countries are banning flights from Britain.
Well, not really. That’s usually true for a very large effective population size, which is what we tend to have for a virus in a pandemic. But there’s genetic drift, genetic hitchhiking. Not all evolutionary outcomes are determined by natural selection.
The BBC article posted above is 5 days old. It says that scientists had not gotten a clear-cut answer yet about whether this strain is more easily transmissible. As of yesterday, the experts were clearly saying it is more infectious – up to 70% more.
Does anyone know how they determine the 70% increase in infectivity?
Four analytic approaches were reviewed regarding the transmissibility of VUI-202012/01
- Growth rate from genomic data: which suggest a growth rate of VUI-202012/01 that
that is 71% (95%CI: 67%-75%) higher than other variants.- Studies of correlation between R-values and detection of the variant: which
suggest an absolute increase in the R-value of between 0.39 to 0.93.- PCR ct values: which suggest a decrease of ct value of around 2 associated with
the new variant.- Viral load inferred from number of unique genome reads: which suggests 0.5
increase in median log10 inferred viral load in Y501 versus N501.It was noted that variations in observed ct values can change with epidemiology since the stage of illness at which infection is detected can vary with incidence of cases, awareness of transmission, and the availability of tests.
It was noted that VUI-202012/01 can be challenging to sequence so estimates of frequency of this variant may be underestimates.
It was noted that whilst previous variants have successfully emerged in periods of low prevalence without clear evidence of having a selective advantage, the emergence and subsequent dominance of VUI-202012/01 in a period of relatively high prevalence suggests VUI-202012/01 does have a selective advantage over other variants.
It was noted that VUI-202012/01 has demonstrated exponential growth during a period when national lockdown measures were in place.
In summary, NERVTAG has moderate confidence that VUI-202012/01 demonstrates a substantial increase in transmissibility compared to other variants.
NERVTAG concluded that there are currently insufficient data to draw any conclusion on:
- Underlying mechanism of increased transmissibility (e.g. increased viral load, tissue distribution of virus replication, serial interval etc)
- The age distribution of cases
- Disease severity
Above was the report that the 70% figure was based on. I haven’t yet tracked down first hand what any subsequent revised opinions or estimates are based on. So the principal piece of evidence was the increase in prevalence of this strain, circumstantial but obviously highly suggestive.
Thanks. I don’t fully understand it but appreciated!
Which explains precisely how we ended up as Tier 4. St Pancras was absolutely packed with people headed north or toward the Chunnel. Madness.
That’s how the affluent spread the Bubonic Plague far and wide.
Really stupid of the government to announce travel restrictions in the afternoon when people still had enough time to flee instead of in the middle of the night.
When I first heard this news, it reminded me of this EAS scenario (there’s a part 2 on the channel as well). I wonder if that scenario will no longer be just a scenario…
-Baleaf