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How many virons to infect? - Printable Version

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How many virons to infect? - M T - 07-15-2020

One of the questions relative to a number of things is how many virons does it take (on average) to cause an infection.  Could the rate of distinct genomes in people suggest a range?

This is far out of my ken, but maybe someone here has seen work along these lines.  Or maybe tell me this isn't how things work.

Suppose it takes only one viron to start replicating and make you sick, and the rate of viable mutations of any replication in the infector was 1 in 1000, then if the infectee became got exposed to a single viron, which then replicated, then the rate of mutations in the viruses in people should be 1 in 1000.

If it took 1000 virons to start replicating before you immune system can't stop it, then most of them would be be the same as the original genome in the infector.  Most of the replicated viruses would be the same genome.  The mutated viron would need to have some replication advantage to become the prevalent genome in the infectee.

If all that is true, then the rate at which genomes change from case to case might suggest how many virons it takes to infect someone.

There's still the issue that you might get 1M virons even if it only takes one to get you sick. 
It may be that 1 viron in the lower lungs is enough, but 1M are necessary in your throat.

Apparently, the Iceland research has the genome for each individual that got sick.

RE: How many virons to infect? - newguy - 07-17-2020

i've been wondering about this for awhile........i've probably been exposed to at least a few individual virus particles.

but i'm less worried now........i just ordered and received a box of 20 N-95 masks.  they don't have valves, but they appear to be genuine.  the box says they were made in China in June of this year.  i didn't go through Amazon, i ordered them directly from one of several companies called Accumed.  this company is headquartered in Houston.  

here's a link to their website:  https://accumed.com/n95-mask-for-sale-respirator-safety-face-mask-z1.html

RE: How many virons to infect? - dabigv13 - 07-17-2020

I hope it's a lot because I just heard a patient I scoped in the ED this afternoon just returned a positive covid test. Unusual case, had been admitted earlier in March with covid, but this presentation was of sore throat and swelling in the throat. Hopefully just some RNA sitting around for months because I was wearing my least favorite n95 today.

RE: How many virons to infect? - akiddoc - 07-17-2020

(07-17-2020, 06:46 PM)dabigv13 Wrote:  I hope it's a lot because I just heard a patient I scoped in the ED this afternoon just returned a positive covid test. Unusual case, had been admitted earlier in March with covid, but this presentation was of sore throat and swelling in the throat. Hopefully just some RNA sitting around for months because I was wearing my least favorite n95 today.

This is not the best time to be in ENT.

RE: How many virons to infect? - magnus - 07-17-2020

(07-17-2020, 06:46 PM)dabigv13 Wrote:  I hope it's a lot because I just heard a patient I scoped in the ED this afternoon just returned a positive covid test. Unusual case, had been admitted earlier in March with covid, but this presentation was of sore throat and swelling in the throat. Hopefully just some RNA sitting around for months because I was wearing my least favorite n95 today.

fingers crossed!

RE: How many virons to infect? - BostonCard - 07-18-2020

You are looking for the ID50 (the dose of viral particles that will cause 50% of people to become infected). It’s not known for COVID-19.  For SARS, in mice, the ID50 was several hundred.  A turkey coronavirus looks to require 10^4.88 particles for transmission.

https://pubmed.ncbi.nlm.nih.gov/30146717/

There’s not much data, but it probably requires breathing in hundreds to thousands of viral particles.  Unfortunately, someone who is infected can shed millions of viral particles.

BC

RE: How many virons to infect? - Erika - 07-18-2020

(07-18-2020, 12:04 AM)BostonCard Wrote:  You are looking for the ID50 (the dose of viral particles that will cause 50% of people to become infected). It’s not known for COVID-19.  For SARS, in mice, the ID50 was several hundred.  A turkey coronavirus looks to require 10^4.88 particles for transmission.

https://pubmed.ncbi.nlm.nih.gov/30146717/

There’s not much data, but it probably requires breathing in hundreds to thousands of viral particles.  Unfortunately, someone who is infected can shed millions of viral particles.

BC

One of the bacterial organisms I was involved in studying was Francissella tularensis which has an astoundingly low ID of 5-10 organisms hence its listing as a select agent (useful to terrorists).

RE: How many virons to infect? - BostonCard - 07-18-2020

https://www.cdc.gov/niosh/nioshtic-2/20037262.html

Were you a co-author?

BC

RE: How many virons to infect? - dabigv13 - 07-18-2020

(07-17-2020, 11:38 PM)magnus Wrote:  
(07-17-2020, 06:46 PM)dabigv13 Wrote:  I hope it's a lot because I just heard a patient I scoped in the ED this afternoon just returned a positive covid test. Unusual case, had been admitted earlier in March with covid, but this presentation was of sore throat and swelling in the throat. Hopefully just some RNA sitting around for months because I was wearing my least favorite n95 today.

fingers crossed!

Some follow up- the positive test was from the rapid test. The Roche PCR test which is probably a better test came back negative today. Hard to know what to make of it all but I do favor the PCR test's accuracy. Still, while I'd expect false negatives from the rapid tests, false positives I would expect to be rare.

And this is btw what it looks like to operate on covid patients. Sans one more layer of gloves and gown. Gets toasty.

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