Marc Johnson Profile picture
May 4, 2024 9 tweets 2 min read Read on X
A few points about the H5N1 outbreak that I'd like to share.

1. If we had a pan-influenza wastewater screen in place nationally that differentiates the influenza sources by sequencing (which isn't that hard to do), we probably would have detected this outbreak months ago.
1/
BTW, we submitted a CDC proposal earlier this year to do exactly this, but the topic was pulled from the BAA so the proposal wasn't even reviewed.
2/
2. We should not panic about the current outbreak in cattle. You aren't going to get influenza from pasteurized milk, and this virus isn't ready for human-to-human spread (yet).
3/
3. What we should be concerned about is that fact that the viruses is getting way too many chances. It keeps expanding its tropism. The more animals it replicates in, the more chances it gets to sample new configurations.
4/
4. When the virus makes it way it to pigs, that is when we need to start getting really nervous. Pigs are a mixing vessel where flu is more likely to adapt to respiratory spread in humans.
5/
5. In my opinion we should be focusing our attention on wastewater testing downstream of meat processing plants (for all types of animals). It wouldn't matter what tissue the virus is in, it would end up in the water and give us an early warning.
6/
We've detected and sequenced pig influenza from such sewersheds before (not H5N1), so I know it can work.
7/
6. Most important, we shouldn't shy away from surveillance because we want to avoid a panic. There is still time to stay ahead of this, but if we aren't careful I think it's just a matter of time before H5N1 makes it to humans.
8/8
4.

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More from @SolidEvidence

Feb 11
Brief update on the new cryptic lineage we found from Petersburg City, Virginia.

We went back and screened all of the samples from that sewershed since the beginning of 2024 and learned a few things about it.
1/ Image
First, I think I was wrong about the lineage being JN.1 derived. I thought it was JN.1 because it had 22926C (455S), but it looks like it only acquired that recently.

In samples as recent as December the lineage lacked 455S and 456L.
2/ Image
That would mean the lineage is BA.2.86-derived, which suggests it was acquired probably early 2024.

Caveat, as @LongDesertTrain points out, persist infections hate 455S. It’s possible that the lineage was JN.1, but reverted at 455, but then gained 2 nt creating 455A.
3/ Image
Read 8 tweets
Jan 31
Wastewater variant update. This is the composite data from over 1,000 US samples collected over the last 6 weeks.
1/ Image
You have to extrapolate a little bit because several changes are shared by multiple lineages.

It appears that the new lineage I mentioned last week (MC.10.1 + 445P) is around 4% and is the fastest growing of the lot. It now has a PANGO designation - PA.1
2/
LP.8 is still expanding is is probably about 12% now. Since it is a KP.3.1.1 derivative, KP.3.1.1* might become dominant again.

LF.7 seems to be holding on too at about 4%.
3/
Read 7 tweets
Jan 26
Here's the latest composite US wastewater data.

It's a little bit confusing this week.

1/ Image
Clearly LP.8 is still the main lineage gaining traction. All of its changes are moving in the same direction (up).

LF.7 is much lower, but looking a little bit more alive than last week.
2/ Image
445P is mixed. It is decreasing, but we know that the signal is a mix of LB.1.3.1 and a new lineage which is MC.10.1+445P (which also has A435S).

445P is decreasing, but much of that is likely the drop in LB.1.3.1 when you compare to 183H.

3/
Read 6 tweets
Jan 24
What fraction of patient sequences are derived from persistent SARS-CoV-2 infections? (volume 3)

This is something that we can actually calculate.
1/
The key is the mutation Orf1a:K1795Q, which frequently appears in persistent infections (and even more often in cryptic lineages).

2/
Each time I make this calculation, I check 2 empirical numbers.

1. What fraction of sequences with Orf1a:K1795Q are from persistent infections

2. What fraction of persistent infections acquire Orf1a:K1795Q

3/
Read 17 tweets
Jan 22
There was a nice paper that recently came out about a patient that had COVID for 521 days.

I find it interesting for different reasons that most though.
1/

nature.com/articles/s4152…
We also study persistent infections, except we don't know who the patients are.


2/
Here's what immediately got my attention, the RBD mutations the clone acquired. Every one of the mutations we've seen before in cryptic lineages.
3/ Image
Read 13 tweets
Jan 5
Interesting, it looks like Atlanta, Georgia has a REALLY old cryptic lineage.

I would call it the CDC variant, but it’s the wrong sewershed.

1/ Image
I didn’t even know Georgia was doing wastewater sequencing, but a bunch of sequences appeared in SRA right after Christmas.

15 of the samples from the sewershed with pop. 190k (Cobb county) had the s2m fix.
2/
The ‘s2m fix’ means the variant is derived from BA.1 (original Omicron) or earlier. This lineage lacked 29742T, so it probably isn’t a Delta.

Strangely, I saw another s2m fix from Atlanta about a year ago, but different sewershed and the sequence doesn’t match.
3/
Read 8 tweets

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