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I was thinking HEPA filtration may already cater for virus's, but with HEPA certification being .3 microns and the COVID-19 virus 0.12 microns, then it gets do

by Zenst 6y ago

I was thinking HEPA filtration may already cater for virus's, but with HEPA certification being .3 microns and the COVID-19 virus 0.12 microns, then it gets down to individual air conditioning systems. Some may use ionising in combination or UV. So I foresee a whole raft of legislation and requirements for office spaces ahead. Which will only help drive the work from home long-term as cheaper office space. But also help shift us away from open plan offices that I've never met anybody who liked. As for herd immunity - that really is best effective against viruses that do not mutate that quickly. Corona-viruses from my understanding, do mutate. Though it is often the case that mutations of a virus over time lean towards mutations that make them less impacting upon the host. Which may be down to natural selection in that those with no impact can spread it more and no virus really wants to kill the host. Impacted/dead hosts tend to be less effective in transmission. So may very well be down to that aspect in why they tend to become less impacting. On the UV aspect https://www.nature.com/articles/s41598-020-67211-2 https://www.nature.com/articles/s41598-020-67211-2 a UV wavelength of 222nm that is effective against the virus and safe for humans. Though how stable current UV output is and by that if you had a 222nm light, over time would that drift and become less human safe is something I'd want to check. There again - flu's and colds are more prevalent during winter months when we have less sun and less UV. Can't ignore that pattern.

nradov 6y ago
All viruses mutate, but so far SARS-CoV-2 has been mutating relatively slowly. It has an error correction mechanism which blocks the majority of mutations. By contrast influenza lacks that error correction and mutates much faster, which is why we need a reformulated vaccine every year. The human species already has a significant level of herd immunity against four other endemic coronaviruses. The same thing will eventually happen with SARS-CoV-2 one way or another, but hopefully we will have an effective vaccine soon enough to accelerate that process while minimizing the death toll.
- beagle3 6y ago
  > By contrast influenza lacks that error correction and mutates much faster, which is why we need a reformulated vaccine every year. That's true, but that might change soon (the "every year", not the mutation speed): Results of [0] are supposed to be published this quarter. I am hopeful for them to be positive. [0] https://www.biondvax.com/2020/07/last-of-12400-participants-completes-final-visit-in-biondvaxs-m-001-universal-flu-vaccine-pivotal-phase-3-clinical-trial/ https://www.biondvax.com/2020/07/last-of-12400-participants-...
segfaultbuserr 6y ago
> but with HEPA certification being .3 microns and the COVID-19 virus 0.12 micron HEPA can filter sub-0.3-micron particles, and the effectiveness trends to be even higher than its performance at 0.3 microns. Although it's not certificated, but it's often true from a practical standpoint, due to the physics of mechanical filtration in general. The reason of using 0.3-micron in certification, is because it's the point where HEPA filters are the least effective. 0.3 um is the most difficult size to filter. Effectiveness goes up at both ends. The effectiveness of HEPA filters trend to follow a U-shaped curve [0]. Below 0.3 um, particles are captured by the diffusion mechanism. Above 0.3 um, particles are captured by the interception and impaction mechanism. Around 0.3 um, neither mechanism is effective, and efficiency reaches a minimum. [0] https://en.wikipedia.org/wiki/File:Filteration_Collection_Mechanisms.png https://en.wikipedia.org/wiki/File:Filteration_Collection_Me...
- tzs 6y ago
  Here's a document from a HEPA filter maker explaining the four mechanisms involved in a little more detail [1]. [1] http://donaldsonaerospace-defense.com/library/files/documents/pdfs/042665.pdf http://donaldsonaerospace-defense.com/library/files/document...
endogui 6y ago
> Corona-viruses from my understanding, do mutate. Already, reinfection by different strains of COVID-19 has been documented (by DNA sequencing) in Korea. The more people who catch COVID-19, the greater the space of possible genetic mutations can be explored. Some of those mutations may decrease severity, but others are likely to merely increase the presympomatic contagiousness period.

by Zenst 6y ago

nradov 6y ago

All viruses mutate, but so far SARS-CoV-2 has been mutating relatively slowly. It has an error correction mechanism which blocks the majority of mutations. By contrast influenza lacks that error correction and mutates much faster, which is why we need a reformulated vaccine every year. The human species already has a significant level of herd immunity against four other endemic coronaviruses. The same thing will eventually happen with SARS-CoV-2 one way or another, but hopefully we will have an effective vaccine soon enough to accelerate that process while minimizing the death toll.

beagle3 6y ago
> By contrast influenza lacks that error correction and mutates much faster, which is why we need a reformulated vaccine every year. That's true, but that might change soon (the "every year", not the mutation speed): Results of [0] are supposed to be published this quarter. I am hopeful for them to be positive. [0] https://www.biondvax.com/2020/07/last-of-12400-participants-completes-final-visit-in-biondvaxs-m-001-universal-flu-vaccine-pivotal-phase-3-clinical-trial/ https://www.biondvax.com/2020/07/last-of-12400-participants-...

segfaultbuserr 6y ago

> but with HEPA certification being .3 microns and the COVID-19 virus 0.12 micron HEPA can filter sub-0.3-micron particles, and the effectiveness trends to be even higher than its performance at 0.3 microns. Although it's not certificated, but it's often true from a practical standpoint, due to the physics of mechanical filtration in general. The reason of using 0.3-micron in certification, is because it's the point where HEPA filters are the least effective. 0.3 um is the most difficult size to filter. Effectiveness goes up at both ends. The effectiveness of HEPA filters trend to follow a U-shaped curve [0]. Below 0.3 um, particles are captured by the diffusion mechanism. Above 0.3 um, particles are captured by the interception and impaction mechanism. Around 0.3 um, neither mechanism is effective, and efficiency reaches a minimum. [0] https://en.wikipedia.org/wiki/File:Filteration_Collection_Mechanisms.png https://en.wikipedia.org/wiki/File:Filteration_Collection_Me...

tzs 6y ago
Here's a document from a HEPA filter maker explaining the four mechanisms involved in a little more detail [1]. [1] http://donaldsonaerospace-defense.com/library/files/documents/pdfs/042665.pdf http://donaldsonaerospace-defense.com/library/files/document...

endogui 6y ago

> Corona-viruses from my understanding, do mutate. Already, reinfection by different strains of COVID-19 has been documented (by DNA sequencing) in Korea. The more people who catch COVID-19, the greater the space of possible genetic mutations can be explored. Some of those mutations may decrease severity, but others are likely to merely increase the presympomatic contagiousness period.