Read on Twitter
Thoughts on infectious dose and symptom severity... a thread.
There is some evidence that lower viral dose leads to less severe symptoms in animal models.
https://twitter.com/BallouxFrancois/status/1277210360118902785?s=20
1/
There is some evidence that lower viral dose leads to less severe symptoms in animal models.
https://twitter.com/BallouxFrancois/status/1277210360118902785?s=20
1/
You might be thinking about social distancing, masks, asymptomatic and outdoor transmission all being factors here.
But let's also consider the viral load itself. It varies over time and ends with low levels being shed up to 83d (avg 17d).
https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciaa1442/5910315
2/
But let's also consider the viral load itself. It varies over time and ends with low levels being shed up to 83d (avg 17d).
https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciaa1442/5910315
2/
If lower infectious dose means less symptoms, then a low enough dose should result in no symptoms at all.
Enter variolation - inoculation in the hope of mild but protective infection.
https://en.wikipedia.org/wiki/Variolation
3/
Enter variolation - inoculation in the hope of mild but protective infection.
https://en.wikipedia.org/wiki/Variolation
3/
In this pandemic we have responded with testing and isolation on a scale never seen before.
Since shedding continues for a prolonged period of time, but culturable virus has been identified up to day 9 of illness, did we miss an opportunity by self-isolating for 14d (in UK)?
4/
Since shedding continues for a prolonged period of time, but culturable virus has been identified up to day 9 of illness, did we miss an opportunity by self-isolating for 14d (in UK)?
4/
Locking down also meant that we had fewer low dose/non-culturable shedders around.
It's important to note that non-replicable in bacterial cultures may not equate inactivated or non-replicable in human hosts.
6/
It's important to note that non-replicable in bacterial cultures may not equate inactivated or non-replicable in human hosts.
6/
In vaccine development, a virus can be inactivated by heat, formaldehyde, gamma or UV radiation (and few other novel methods).
https://pubmed.ncbi.nlm.nih.gov/31334909/
7/
https://pubmed.ncbi.nlm.nih.gov/31334909/
7/
With the last one in mind, perhaps there's more to sun exposure than Vit. D? Our climate may not only affect virus seasonality by temperature, humidity and Vit. D but also by the amount of UV-inactivated virus available. Did we miss an opportunity in the Summer?
8/
8/
"Mean decay rates (± SD) in simulated saliva, under simulated sunlight levels representative of late winter/early fall and summer were 0.121 ± 0.017 min−1 (90% loss, 19 minutes) and 0.306 ± 0.097 min−1 (90% loss, 8 minutes)"
https://academic.oup.com/jid/article/222/4/564/5856149
9/
https://academic.oup.com/jid/article/222/4/564/5856149
9/
We know that overreaction can be damaging, just like under-reaction. That's why we need to adjust our response to the evolving evidence exposing unique characteristics of the pathogen.
I hope we'll see more news like this, for many reasons.
https://www.bbc.co.uk/news/health-55274147
10/10
I hope we'll see more news like this, for many reasons.
https://www.bbc.co.uk/news/health-55274147
10/10
@c19d3k2 something we’ve been talking about on and off above.
