Alexandre Bolze Profile picture
Apr 8, 2021 11 tweets 5 min read Read on X
Weekly update from @my_helix SARS-CoV-2 surveillance program.

Check dashboards here: public.tableau.com/profile/helix6…

As reported by @CDCDirector, B.1.1.7 represents more than 50% of cases in US. And fraction still increasing.

See 7 states where Helix tests a lot. Details in 🧵
2/
Before going in details on B.1.1.7, here are some stats on vaccinations in US from @CDC. What an effort! I am very optimistic for the US.

Also important to note that all vaccines work very well against the B.1.1.7 variant. It is really incredible how well they work.
3/
California

Fraction of B.1.1.7 is still increasing. Numbers are small, but I think we may have enough information to look closely at direct competition between B.1.429 and B.1.1.7. Hypothesis is that B.1.1.7 is more transmissible.
4/
Quick note on SGTF

stands for S Gene Target Failure
Also called S Gene drop-out

When we do a PCR test, we look at S gene, N gene & ORF1a. B.1.1.7 variant has a deletion in S gene interfering with test leading to a positive signal in N & ORF1a targets, but not S target.
5/
Florida

Y-axis is different, but it is still clear that B.1.1.7 counts are growing steadily, while non-B.1.1.7 cases are now flattening (after a long decrease).
6/
Georgia

In our tests, one of the states with highest fraction of cases being B.1.1.7. Counts increasing, but slower than MI for example.
7/
Massachusetts
8/
Michigan

There is a lot of talk about MI. Because cases increasing fast. Counts below are pretty clear.

Looks like conditions start of Feb favored virus (as non-SGTF also started to rise), and B.1.1.7 took fully advantage of it.
9/
North Carolina
10/
Pennsylvania
11/
This is it for this update.

For other states check our dashboard. You can also check @nytimes nytimes.com/interactive/20…

@LaurenLeatherby does a much better job than me at presenting these numbers :)

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More from @alexbolze

Dec 9, 2023
Our latest study is live on @medrxivpreprint


We asked why some (unvaccinated) individuals remain asymptomatic after SARS-CoV-2 infection, using 3 large cohorts.

And learned a lot on HLA & role in chronic phase of infection vs. acute phase

Check 🧵medrxiv.org/content/10.110…
Not everyone responds the same to SARS-CoV-2 infection, even before vaccination.

One of the clearest example is the UK SARS-CoV-2 Human Challenge Characterisation study.

Only 1 of 18 infected was asymptomatic. Severity of infection is like a quantitative trait. Image
So why do some get develop a life-threatening pneumonia while others remain asymptomatic?

Older age was the 1st identified risk factor.

Based on genetic studies of other infectious diseases, we and others hypothesized that genetic variants may play a role incl. IEIs & HLA. Image
Read 20 tweets
Mar 13, 2022
Curious about Delta-Omicron recombinants?

Our study 👏 @shishiluo @my_helix: medrxiv.org/content/10.110…

Co-circultation of both variants
20 samples with co-infections
Evidence of a few recombinations in co-infections
& 2 infections with 100% recombinant

Details in 🧵
@shishiluo @my_helix 2/
Recombination is one way a virus can evolve. It allows to 'test' a new combination of mutations, which could provide an advantage or not.

A great review on how RNA viruses recombine: nature.com/articles/nrmic… by @edwardcholmes @SimonLoriereLab

For SARS-CoV-2, should be 👇
@shishiluo @my_helix @edwardcholmes @SimonLoriereLab 3/
Lots of talk about Delta-Omicron possible recombinations because in worse case scenario, it could be a bad combo. But also simply because
- it was likely to happen de to co-circulation of both
&
- also easier to identify because of high number of unique mutations of each
Read 13 tweets
Feb 13, 2022
BA.2 situation in 🇺🇸

Latest @my_helix sequences (from today): BA.2 was 9 of 780 in samples from Feb 01 - 04.

- BA.2 seems to be ~1% in USA for now.
- BA.1.1 at ~75%

public.tableau.com/app/profile/he…

and in other countries?
2/
BA.2 is dominant in:
India, Denmark, Sweden, Singapore, Austria, South Africa & Philippines

Check out the awesome graphs on covariants.org/per-country

by @firefoxx66 and her team
3/

To try to 'predict' what may happen in the USA in next couple of weeks, we can look what was the BA.1.1 situation in these countries before BA.2 took over.
Read 7 tweets
Feb 12, 2022
1/

A couple more days of data from @my_helix surveillance:

BA.2 back up at ~1% on Jan 29 & Jan 30

Still growing much slower than what expected, but maybe a sign that it is not completely at bay

Jan 29:
1 Delta
162 BA.1
465 BA.1.1 (73%)
7 BA.2
2/

So far, it does not look like any state in the US is particularly enriched for BA.2. Numbers correlate with sampling by state.

See 👇

source: public.tableau.com/app/profile/he…
3/
Is BA.2 really growing slower in US compared to other places?

Best way to check is to look at the incredible CoVariants website by @firefoxx66

covariants.org/per-country

And look at ratio of 21K (Omicron BA.1 & BA.1.1) vs 21L (Omicron BA.2)
Read 5 tweets
Feb 10, 2022
Great talk from @ETCirulli at @DukeCAGPM this morning on

her research with @my_helix @HealthyNV @grzymski & @uk_biobank

to identify the best genes and variant models to include when doing genetic screens in the entire population

🧵
2/
Screening an entire population is different than doing the exome to identify cause of a rare disorder.
3/
The goal is to select gene <-> disease combinations that look like the one on the right in graph (Disease Z)

A large fraction of carriers (of a genetic variant) will present the disease if nothing is done
& strong enrichment in carriers compared to non-carriers.
Read 7 tweets
Jan 28, 2022
Why does 1-3% of people develop very severe COVID-19 (before vaccine)?

Many studies showed the importance of type 1 IFNs, starting with human genetics see 🧵)

Reviewed by @tutu_ZQ @casanova_lab & COVIDHGE consortium

nature.com/articles/s4158…

1/9
Human genetics often allows to show causation. For severe COVID-19, the first strong hint was that:

- a couple young patients with critical COVID-19 had autosomal recessive deficiency of IRF7 or IFNAR1

- experiments showed that their cells could not control SARS-CoV-2

2/9
More human genetic evidence came with an enrichment of young male adults with X-linked TLR7 deficiency in cases vs. controls.

Again pointing that defect in type 1 IFN pathway, linked to plasmacytoid dendritic cells led to critical COVID-19

3/9
Read 9 tweets

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