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Dr Emma Hodcroft Profile picture
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15 Jan, 11 tweets, 6 min read
Lots of tweets about this today!
Let's see what we can see in the focal S:E484 build!

Phylogenetics (what I do - making 'family trees' from virus genetics) can be very informative to see how different variants are spreading, and how cases link🙂

1/10

independent.co.uk/news/health/br…
There are two variants circulating predominantly in Brazil:
- 20B/S.484K seems to be older & more widespread. It has (among others) a mutation at position 484
- 20J/501Y.V3 is smaller & detected recently. It has mutations at 501 *and* 484.

2/10

nextstrain.org/groups/neherla…
The variant predominantly in the UK (501Y.V1 / B.1.1.7) and the variant predominantly in South Africa (501Y.V2) also both have 501. 501Y.V2 *also* has the 484K mutation.

Why are there concerns about these mutations? You can read more at CoVariants.org!

3/10
The view below is from an analysis focusing on sequences with a mutation at 484. It shows all the samples in the 2 variants (20B/S.484K & 20J/501Y.V3) & how they're related. More closely related = closer together (very, very roughly).

4/10
We can colour these samples by region to see where they're from. As we expect - most are in Brazil! A few are in Argentina (also red).

5/10

nextstrain.org/groups/neherla…
If we look just at 20B/S.484K (top cluster), we can see there are clusters of sequences in the UK, Canada & the USA, and exports to Norway, Malaysia, & Australia.

6/10

nextstrain.org/groups/neherla…
Importantly, the clusters in the USA & Canada are identical (though each country also has an additional imports), so they may be from a group of travellers returning, rather than local transmission (left pic). They also date from Nov - so not recent (right pic).

7/10
We can see 8 UK sequences in the 20B/S.484K cluster. There are 2 clusters, but neither are identical. They could be from a common exposure (same part of Brazil, same travel group), or possibly be local transmission. These samples are from Nov & Dec.

8/10

nextstrain.org/groups/neherla…
If we look at 20J/501Y.V3, we can see that sequences only are found in Brazil and Japan (known travel to Brazil), but no other countries.

9/10

nextstrain.org/groups/neherla…
Hopefully, this thread helps distinguish what the '2 variants' are that are circulating in Brazil, and from which there have been samples detected in the UK.

And, I hope it shows how phylogenetics can help us 'tell viruses apart' & follow them as they move & change!

10/10
To add: why are scientists concerned about these variants circulating primarily in Brazil?

@BillHanage write a fantastic thread here:

11/10

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Dr Emma Hodcroft Profile picture
14 Jan
There's been a lot of news today about 'new variants in Brazil' & 'S:E484' and 'Ohio variants'. A short thread discussing what we know about each.

1/11

#SARSCoV2 #Ohio #BrazilVariant #Brazil #COVID19
There are two variants circulating in Brazil: 20J/501Y.V3, recently detected in Japan & prevalent in Manaus. And temporarily-labelled '20B/S.484K', a larger clade circulating more widely in Brazil.

They both carry the spike mutation 484K, though this arise separately.

2/11
S:E484K is also found in 501Y.V2 (primarily circulating in South Africa).

Why are we particularly concerned about S:E484K? You can read more at CoVariants.org, as discussed in a tweet from earlier this week:

3/11

Read 14 tweets
Dr Emma Hodcroft Profile picture
14 Jan
The focal S:N501 build is now updated with data from 13 Jan!

There are a total of 247 non-UK & non-South African sequences in 501Y.V1 (B.1.1.7 #b117) & 501Y.V2.

I'll do an additional thread later on, covering S:E484 & the 'Ohio variants'.

1/18

nextstrain.org/groups/neherla…
There are 244 new sequences in 501Y.V1 (B.1.1.7) from Australia, Belgium, Denmark, Germany, India, Israel, Italy, Netherlands, New Zealand, Norway, Portugal, Singapore, Spain & USA, as well sequences as from Ecuador and Greece for the first time.

2/18
Greece has 3 new sequences in 501Y.V1 for the first time. They indicate 2 separate introductions.

Ecuador has 2 sequences for the first time. They also indicate 2 separate introductions.

3/18
Read 19 tweets
Dr Emma Hodcroft Profile picture
12 Jan
Happy Tuesday! The latest focal S:N501 build is now updated with sequences from 11 Jan.
There are 101 new sequences in the 501Y.V1 (B.1.1.7 #b117) & 501Y.V2 variants.

Additionally, I'll include some updates on S:E484K in this thread.

1/20

nextstrain.org/groups/neherla…
There are 97 new non-UK sequences in 501Y.V1, including the first sequences in the cluster from Slovakia, Mexico, & Belgium, plus additional sequences from the Netherlands, Denmark, Australia, Spain, Ireland, & Sweden.

2/20
Slovakia has 10 sequences that fall in 501Y.V1 for the first time. These are closely linked, & likely indicate a single introduction and ongoing transmission (remember: vertical distance is not meaningful on the same branch - position of the 2 English samples is arbitrary).

3/20
Read 23 tweets
Dr Emma Hodcroft Profile picture
9 Jan
To add to the excitement of your Saturday evening, the focal S:N501 build is now updated with data from 8th Jan, including 48 new seqs in 501Y.V1 (B.1.1.7 #b117) & 501Y.V2.

1/12

nextstrain.org/groups/neherla…
There are 46 new non-UK sequences in 501Y.V1, from the Netherlands, Italy, Israel, Ireland, Norway, Sweden, the USA, and Luxembourg.
And 2 new non-South African sequences in 501Y.V2, from Australia for the first time.

2/12
In 501Y.V1:

Ireland has 4 new sequences (orange). 2 sit separately but are identical, indicating an additional introduction. 2 link to a previous sequence (green), 1 mutation away each. This could indicate location transmission, unsampled diversity, or a common exposure.

3/12
Read 12 tweets
Dr Emma Hodcroft Profile picture
9 Jan
I'm getting some questions about this, so here you go: We do not have sequence evidence of a new, more transmissible "US variant" - it seems to be a misinterpretation.

Still, more sequencing in the US (& globally) will help us better track existing & emerging #SARSCoV2 variants!
Importantly: you can have spikes & rises in #SARSCoV2 infections without needing a new variant. We can see this clearly in Europe in autumn: we have a good idea of the variants circulating & no new (or old) variant is responsible. It was likely weather-related.
Similarly, season & holiday related changes in travel & behaviour, changing restrictions/mandates, school & university terms, & 'restriction fatigue' - just to name a few - can play a role in #SARSCoV2 case numbers. We can't & shouldn't blame every rise on a new variant.
Read 4 tweets
Dr Emma Hodcroft Profile picture
8 Jan
A brief update to the focal S:N501 builds to start your Friday off right! This one includes data from 7 Jan 21.

We have about 20 new sequences each in 501Y.V1 (B.1.1.7 #b117) & 501Y.V2.

Let's take a look at the new sequences, starting with 501Y.V1

1/14

nextstrain.org/groups/neherla…
There are 22 new non-UK sequences in 501Y.V1, including for the first time from Luxembourg (3), & additional seqs from Singapore (1), Australia (4), France (12), & Switzerland (2).

2/14
First, Luxembourg has 3 sequences in 501Y.V1 for the first time. Each represents a separate introduction.

3/14
Read 14 tweets

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