Someone made an interesting point that we got rid of cholera by drinking cleaner water and that we'll get rid of Covid by breathing cleaner air.
If someone standing in front of you sneezes, a filter in the HVAC isn’t doing anything to stop you from getting covid.
I mean, isn’t airborne transmission still uncertain for Covid?
I don't think there's any uncertainty left in airborne transmission: https://www.forbes.com/sites/jvchamary/2021/05/04/who-corona...
https://pubmed.ncbi.nlm.nih.gov/16696450/
>Abstract
>Recent investigations into the March 2003 outbreak of SARS in Hong Kong have concluded that environmental factors played an important role in the transmission of the disease. These studies have focused on a particular outbreak event, the rapid spread of SARS throughout Amoy Gardens, a large, private apartment complex. They have demonstrated that, unlike a typical viral outbreak that is spread through person-to-person contact, the SARS virus in this case was spread primarily through the air. High concentrations of viral aerosols in building plumbing were drawn into apartment bathrooms through floor drains. The initial exposures occurred in these bathrooms. The virus-laden air was then transported by prevailing winds to adjacent buildings at Amoy Gardens, where additional exposures occurred. This article reviews the results of the investigations and provides recommendations for maintenance and other measures that building owners can take to help prevent environmental transmission of SARS and other flulike viruses in their buildings.
P-traps can dry out though, but they stink if they do. Maybe that's what happened there?
Edit: yes, that's the theory - floor drains with dry u-bends allowed the poop air out.
The important takeaway is SARS 1 had significant fecal-oral transmission and not just respiratory.
And yet I'm supposed to believe that SARS 2 is respiratory only despite the fact that the government has detected SARS 2 in sewer systems, one of the early Covid symptoms is diarrhea, and SARS 1 had significant number of infections by fecal matter.
Hopefully this will help.
This virus isn't going anywhere until we develop an actual vaccine that stops it. I, personally, bet on CRISPR-based or similar solution.
Filtering air will slow it down, but it cannot stop it.
This doesn't have sweeping applicability. It won't stop covid among the general population. Its for maybe hospitals that are on super covid lockdown that want a little more protection for their most vulnerable patients.
We get rid of covid through mass vaccination like any other virus. There's no shortcuts for those who refuse masks and vaccines.
- Extended time indoors, with high viral loads. It spreads ridiculously well with no protection (even among the vaccinated).
- Isolated superspreader events, where one person infects many, even with distant contact.
Filters would seem to target the latter more than the former.
how do you know? it seems like most cases are attributed to the nebulous "community spread" and nobody is really sure who they're coming from or how we're catching it. maybe we are getting it from the person breathing near us - if masks help, i don't see a reason that improved air filtration wouldn't.
It’s as if we all forgot how viruses work.
One of the big factors of "better protection" of immunity gained after recovering from the virus is survivor bias. In data about mortality after reinfection there are no people who died after getting it for the 1st time. This leaves only ones who had body strong enough to recover.
There's no surprise that later that group fares better.
but at least in my region, the majority of cases still don't have a known source. maybe that's because people are catching it in scenarios where they're in close proximity to somebody for extended periods of time but forget about it when the contact tracers call them, and all cases are spread that way.
or maybe it's spreading in grocery stores and other casual contact scenarios but that's just impossible to measure or count. we keep hearing that there's no evidence of it spreading in schools, and yet as long as students are in school it spreads a lot more among students. is it not spreading there, or is it just really difficult to find the evidence of that?
It's not obvious to me that in-room air filters wouldn't reduce the exposure in this case, as the original commenter claimed? If it reduces the virus in the air, as the OP study finds, it seems like it probably would reduce virus exposure and thus infection rate when spending long periods indoors in close proximity, no?
Sure, just because it reduces the virus in the air doesn't necessarily mean it reduces infection -- like hypothetically the virus could commonny be going right from someone's exhale to someone else's inhale without having a chance to be filtered -- which I think is what the original commenter was suggesting -- but that's not the "spending long periods" scenario at all. I think it's true that while you probably can get infected in as little as ~15 minutes (not necessarily in just a couple minutes), but also clear that the longer you are in the same room, the higher risk.
But sure, we don't know exactly everything. All we can do is build knowledge one brick at a time, AND all we can do is act on the bricks we already have (that we don't have the whole wall yet is not a reason to avoid acting on our best picture (mixed metaphor, sue me) form what we do have)... but reducing virus in the air is a pretty huge brick for a respiratory infection. Based on everything we do know, it is hard to believe what the original commenter asks us to, to believe that reducing viral concentration in the air would NOT significantly lower infection rate.
I think it's becoming increasingly clear we should be spending at least as much attention on HEPA air filtration as people have been on masks.
if you are having trouble visualizing how this works, imagine a perfume dispenser jetting out a fine mist, that's your covid positive person exhaling. In an enclosed small room, the concentration of that particulate mist is much higher than in a large room, and unable to disperse quickly without any ventilation. Over time, you will inhale more and more of this particulate in this room at this concentration, and you will hit the infectious dose level eventually. If you are outside, or in a larger or well ventilated room, concentration of the particulate is much smaller since its either dispersing into a greater volume of air or being removed from the area due to ventilation, and it might take you a long period of time to inhale enough particulate at this comparatively lower airborne concentration in order to become sick. Outside, even in a protest, the volume of air is so large in which to disperse particulate that the risk of getting an infectious dose is negligible even with someone yelling right next to you.
So, I have seen a lot of these papers, but too much feels like post hoc justification. I'm game for being cautious, so I'm not really saying to do anything different, but I do want to urge way more caution in messaging than I'm seeing. It is fair and ok to talk of the uncertainty.