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Dr Emma Hodcroft Profile picture
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24 Dec, 4 tweets, 3 min read
Merry Christmas! 🎄 The latest focal S:N501 build is now up.

Zooming in on 20B/501Y.V1 (SE England variant), we can see new sequences in Europe from the Netherlands.

1/4
#Newcoronavirusvariant #SARSCoV2 #ChristmasCovid

nextstrain.org/groups/neherla…
Zooming in on this further, and switching to divergence view (showing mutations rather than time), we can see they share 1 unique mutation & then have 1 unique mutation each, suggesting 1 introduction, possibly from the UK, & onward transmission.

2/4
nextstrain.org/groups/neherla…
We can take a similar look at the Danish sequences. They too, share one unique mutation, & some further unique mutations, suggesting a single introduction & onward transmission.

3/4
nextstrain.org/groups/neherla…
Finally, we can also see the new sequence from Singapore.

Remember: though all these sequences nest closely in UK diversity, the UK generates data much more than other countries, so there could be unsampled links which might fit between samples.

4/4
nextstrain.org/groups/neherla…

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Dr Emma Hodcroft Profile picture
24 Dec
On this Christmas Eve, I would like to spare a thought for the many scientists, researchers, & lab technicians & assistants who have been 'called up' thanks to the new #SARSCoV2 variants.
It's been a tough year & many of us had hoped this week might be a well-earned break.

1/6
Academia/science is rarely a 9-5 job, & we're a bit famous for our tendency to overwork, but it's a rare year when evolutionary biology & phylogenetics are so urgently needed that we can't slip away for a few quiet days over Christmas!

2/6
(see alt text for the ornament shop!) https://www.etsy.com/listing/883890228/plush-virus-in-face-m
I imagine many, like myself, are humbled & proud that we can contribute to the efforts against #COVID19 #SARSCoV2.
But it's been an incredibly long, hard year for many of us, compounded by the same restrictions, loss, & loneliness that so many have felt.

3/6
Read 6 tweets
Dr Emma Hodcroft Profile picture
23 Dec
A case of the '#SouthAfrica' variant has been detected in the UK. There's also talk about a 501Y mutation in Wales.
It's getting confusing!

First: all 3 of these 501Y mutations are independent. It's appeared a few times, separately.

#Newcoronavirusvariant

1/10
We can see this because the 3 variants (UK=1, Wales=2, SA=3) are not next to or inside each other in the tree below. In fact, we need to trace back to before March to find their common ancestors:

2/10

nextstrain.org/groups/neherla…
Are the UK and South Africa variants the same? No. See this thread for more info:

Critically, the SA variant does not have the 69/70 deletion we see in the UK variant.

3/10

Read 10 tweets
Dr Emma Hodcroft Profile picture
21 Dec
Switzerland has now banned flights from the UK - following on from an increasing number of other countries.

If the new UK variant may already be in more countries across Europe, why are countries stopping flights from the UK?

#SARSCoV2 #COVID19

1/10

In short: numbers matter.

The number of people with the new variant in continental Europe is likely still small: with testing, tracing, identification & restrictions, we might be able to prevent them from passing the virus on. That's easier with 10 people than 1000.

2/10
However, border closures make the most sense when coupled with fast action *inside* countries as well.

Even a few cases can become a few thousand quickly, if there's nothing to stop them. So as well as border controls, countries need to be stepping up measures within.

3/10
Read 11 tweets
Dr Emma Hodcroft Profile picture
20 Dec
From the latest data available on GISAID this morning, an updated S:N501 #SARSCoV2 build is available.

We now have a clade label for the South African variant (20C.501.V2) & will add one for the UK variant soon.

No major additions to the tree.

1/4
nextstrain.org/groups/neherla…
The latest data identified additional sequences in S:501 mutant variants from the UK, Denmark, Australia, & South Africa, but no additional countries.

(!This table does not distinguish variants & some countries listed haven't seen 501 in months!)

2/4
github.com/emmahodcroft/c…
From the plot of variants frequency in sequences, per country, we can see that the 501Y variant (pink) is expanding in the UK (the last data point represents incomplete data & will likely change in future).

3/4
github.com/emmahodcroft/c…
Read 5 tweets
Dr Emma Hodcroft Profile picture
19 Dec
Is the new UK variant the same as the new South African variant (501Y.V2)?

No.

They both share the same mutation in spike: N501Y (N->Y at position 501). However, the 2 variants have arisen separately.

1/N
nextstrain.org/groups/neherla…
In the tree below, the UK variant is in green at the top. The SA variant is the one with large yellow circles nearer the bottom.

Though it's a bit hard to see in this tree, they are quite distant genetically: they have many mutations they do not share!

2/N
S:N501Y has occurred multiple times around the world. Not all of these have risen & become prominent. So the role of 501Y is probably more complex.

UK variant & SA variant both have many other mutations that are being investigated.

3/N
Read 15 tweets
Dr Emma Hodcroft Profile picture
17 Dec
Two new variants are now up on the #SARSCoV2 #COVID19 Mutations of Interest site! 🎉

Added
- Spike 69 deletion (S:H69-)
- Spike V1122L (S:V1122L) - primarily circulating in Sweden.

(More detail on each on the site coming soon - but thread below!)

1/9
github.com/emmahodcroft/c…
S:H69- is of particular interest, as it's part of a double-deletion (also position 70) that's appeared at least 3 times independently in conjunction with receptor binding domain (RBD) mutations: N501Y, N439K, & Y453F.

2/9
nextstrain.org/groups/neherla…
Below, the yellow is N439K, the orange is Y453F associated with Denmark (we see Y453F mutation multiple times) & the red is N501Y (again, we see N501Y mutation multiple times). Each of these RBD mutations also exists without the 69/70 deletion.

3/9
nextstrain.org/groups/neherla…
Read 10 tweets

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