no the new mutation is not more dangerous..

there are actually something like 4000 strains of covid19.

what they are fnding is in some communities certain strains pass on more then others due to the human ignorance of respecting advice.

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lets word it another way.
its easy to identify humans vs apes right?
wel within the easy identification of humans. there are subset mutations of blonde hair ancestry and ginger hair ancestry. and brown hair ancestry.. right?
nothing in human genes makes any haircolour more of less sex addictive than each other.
but following the generations you end up seeing more area's filled with gingers(north) and light/dark hair in the south

this is not due to gene risk of higher pregnancy. but in human movement and mingling

what is found is londoners are ignoring the rules so the strain in the london population is spreading more then a strain imported from the netherlands. or the strain in the cornwall community
all due to the people passing it around obeying or disobeying the rules

for instance the strain in cornwall is not passing around much due to people actually staying home more in cornwall than londoners. it is not becasue the cornwall strain is a safer mutation.

back to human analogy
however overall a person from cornwall vs a londoner might have subtle differences. but overall can be easily identified still as a english human. which is why its not a threat to the vaccine.

a massive change would need to occur to confuse the immune system of vaccinated people. such as if londoners had mixed species relations with their pets, making a non complete human hybrid

so far the mutations are so subtle that the 'spike protein' still has enough identifiers to know the difference between all covid strains vs say a new hybrid

the only threat is cross-species mutations. suck as the the news of the camels in egypt and the mink in netherlands. where by it completely mutates in a different direction in mink than it would in the human-human strains. and then if later the mink strain re-entered human population. then those hybrids would not be the same as covid19 subtle strains..

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anyway all the news about the london strain is showing that more people are getting infected due to londoners disobeying the rules. meaning londoners cannot complain/blame other area's importing the virus into london and it is infact londoners themselves spreading it.
if it was imported from other areas visiting london then the numbers of strains of the london strain would be diluted.

yep they actually do use the strains to trace the path a infection follows and can work out where a strain began and if its 'domestic' or 'imported'

this is why they dont want londoners exporting their strain. so thy lockdown restricts movements out of the area.
if it was an imported strain. they would shut down the airports and roads into london

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they use these strain identifiers to work out contact tracing. for instance a strain in a university if that shows many university people are mingling too much and passing it around by disobeying the rules. they can then see if the university strain becomes the most majority strain in an area. and decide to restrict students movement while still letting other clusters in retailer remain open because not many are mingling around retail stores.. or the opposite if analysis shows the opposite occurances