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Marc Johnson Profile
Marc Johnson

@SolidEvidence

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Molecular virologist, Professor, and wastewater detective. Same handle on bsky. Ignore the check, I'm doing an experiment.

Columbia, Mo.
Joined January 2022
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@SolidEvidence
Marc Johnson
7 months
Do you think you've had long-term GI problems since having Covid? .We are performing a study examining the characteristics of viruses, specifically persistent SARS-CoV-2 infections, in stool samples. 1/3.
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@SolidEvidence
Marc Johnson
20 hours
That's it for now. We continue to recruit more sewersheds in partnership with @SecureBio. More updates to come. 10/10.
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Marc Johnson
20 hours
This is fascinating. Although the rhinoviruses were usually surging in Spring, there was an outbreak of C42 in Fall of last year and it occurred in every one of the sewersheds coast-to-coast. Who knew?.9/
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@SolidEvidence
Marc Johnson
20 hours
And if you look at the other locations, most of the serotypes prevalent in Columbia this year were prevalent everywhere. 8/
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@SolidEvidence
Marc Johnson
20 hours
The rhinoviruses have been most prevalent in late Spring, and most of the prevalent serotypes in Columbia last year are not prevalent this year. 7/
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@SolidEvidence
Marc Johnson
20 hours
In the legend you can toggle the different sewersheds we are reporting (hopefully adding more soon). 6/
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@SolidEvidence
Marc Johnson
20 hours
First, we only listed the serotypes that have appeared in at least 4 consecutive samples. They are ordered based on when they first appeared in 4 consecutive samples. Time goes left to right, starting in 2024. Larger circles mean more of that serotype detected. 5/
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@SolidEvidence
Marc Johnson
20 hours
We debated how to best display this. There are over 100 rhinovirus serotypes, and we wanted to display their prevalence over space and time. Too many dimensions. This was our first stab at it. 4/
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@SolidEvidence
Marc Johnson
20 hours
As promised, we've now added a standalone readout of the rhinoviruses on our wastewater dashboard. 3/.
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@SolidEvidence
Marc Johnson
20 hours
Contrary to my prior assumptions, many of the most common pathogens are not everywhere, all the time. They occur in discrete waves, often nationwide. I wrote about this recently with Rhinoviruses, the most frequent cause of the common cold. 2/.
@SolidEvidence
Marc Johnson
11 days
This is cool. I was poking around at the Rhinovirus (common cold) data and realized that my perception about these viruses was completely wrong. 1/
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@SolidEvidence
Marc Johnson
20 hours
I've always found this frustrating. You or your child has a respiratory infection. It's not flu or COVID. Your doctor can only tell you, 'you have a virus'. Could it be a little bit more specific?. We hope to help answer this question, non-invasively, and for free. 1/
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@SolidEvidence
Marc Johnson
3 days
4 part. What movie featured this bridge?.Who directed?.What actor has been in the most films of that director?.What was that actor’s best film?
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@SolidEvidence
Marc Johnson
3 days
Tougher one. Where am I?
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@SolidEvidence
Marc Johnson
7 days
Where am I?
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@SolidEvidence
Marc Johnson
9 days
Where am I? Be precise.
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Marc Johnson
11 days
This probably isn’t a surprise to real epidemiologists, but it was a revelation to me. Anyway, I think we’re going to have to add a rhinovirus breakdown on our dashboard. 16/16.
@SolidEvidence
Marc Johnson
12 days
I’m thrilled to announce the update of our water surveillance dashboard. Many improvements, and our first substantial move into ‘OneHealth’. Read to the end to find the Easter Egg. 1/.
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@SolidEvidence
Marc Johnson
11 days
Presumably each season we get a little bit of herd immunity against the serotype that is surging, so it is outcompeted the next season by an antigenically distinct serotype. 15/.
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@SolidEvidence
Marc Johnson
11 days
This suggests that rhinoviruses really are more like influenza. It’s not a continuous swarm, but rather a bunch of discrete, nation-wide (world-wide?) surges of individual serotypes. 14/.
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@SolidEvidence
Marc Johnson
11 days
More importantly, the serotypes surging in Columbia in 2025 appear to be surging everywhere. 13/
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@SolidEvidence
Marc Johnson
11 days
Then I looked at the variation geographically. We weren’t sampling other sites in the 2024 season, but the serotypes that surged in Columbia in 2024 didn’t appear to surge anywhere in 2025. 12/
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Marc Johnson
11 days
That’s when I noticed something striking. Most (but not all) surges were in Spring, and the surges were season specific. While there were surges both years, the majority of the serotypes that surged in 2024 were replaced by different serotypes in 2025. 11/
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