Ventilation and Viral Evolution

I watched a great webinar from OHCOW (Occupational Health Clinics for Ontario Workers) on, in the first half, Covid and ventilation, specifically in congregated settings, with Amy Katz, a knowledge translation specialist at St. Michael's Hospital, and Dr. Amy  Li, a civil and environmental engineering professor at University of Waterloo. The second half featured Dr. Ryan Gregory, an evolutionary biology prof from University of Guelph. I think the video will show up here soon, and there are other great resources on that page as well. This is a loose paraphrasing of what I heard in those two hours:

Katz and Li helped to write a checklist for community spaces: "Reducing Transmission of Covid-19 Through Improvements to Indoor Air Quality" in a group including engineers, lawyers, and immunologists. The project started in October 2021, spurred by the question, Does the guidance published by Public Health include indoor air quality measures, and reflect the evidence of the time? The answer is "no."

They started with the shared assumptions (aka facts) that Covid is airborne, that ventilation, filtration, and UV remove (or sterilize) respiratory particles from the air, and that certain shared spaces are high risk, like shelters, LongTerm Care homes, group homes, and prisons.  They're vulnerable groups generated by the state and colonization and ableism. The numbers are upsetting:

They searched all Toronto Public Health resources for anything about cleaning the air and found almost nothing. Then looked at the Public Health Ontario, and also found nothing on ventilation or filtration. Many local public health units use the PHO guidance despite the lack of information. They looked at PHO guidance systematically and found no mention or just brief mention of cleaning the air. So they started creating plain language resources to help clarify what's necessary to reduce transmission. Often they hear that people (owners/manager) know what's necessary, but they need some kind of official guidance to compel people to act. That's where the checklist comes in to help generate action. A calculator can be a starting point, but building owners/managers still have to consider factors like air flow rate, pressurization, number of occupants, and types of activities. The Conversation has a good summary of their work.

Then Dr. Gregory spoke on the connection between evolutionary biology and studying viruses. Decisions on how to communicate have impacts on perception, sometimes by design and sometimes by chance. Everything is Omicron now, but many variants within Omicron are very different from one another. It's like talking about mammals as a group - there's a huge difference between a mouse and a whale. The viruses that have the advantage can be due to replication time, attack locations or transmissibility. Mutation can happen in a host that has more than one version or a mutation of one that adds variations, and it's more likely to occur in people who stay infected for a longer time, like in immunocompromised. Also mutations happen within communities, in which case it matters more how quickly it can travel and survive longer outside the body. The advantage is given to viruses that attack a more accessible body part so they're better at getting into host cells. 

So "It behooves us all to protect the vulnerable. That's where theses divergent variants evolve."

There's a myth that viruses evolve to be more mild, which just isn't true. Virulence is a byproduct of other things going on. And there are myths around endemics. People think it means it becomes mild. It's become a goal where it will be manageable or livable, but that's a misuse of the term. Endemic means that it's present in an area at a constant amount. It doesn't mean it's not dangerous, e.g. measles can be endemic in a place, and very dangerous. 

Omicron started in December 2021. It's been a year. Don't expect it to be the last one. Last November, some experts argued that Delta was the last big variant, and vaccines worked to contain it. Then Omicron blew up. 2022 has been the deadliest year for the pandemic in Canada. So far we've had 46/day pre-Omicron and 53/day after Omicron. and there's no hybrid immunity. 

This past summer was vastly worse than the previous two, and the numbers never came back down. We had waves before, but now we just have a high tide. It's deeply important to talk about how not-low the low points are:

We're seeing collections of mutations being favoured specifically because they confer immune escape and are resistant to some treatment we use, so we're losing some of the tools that got the variants down. Now instead of linear variants coming one at a time, we have a cloud of variants, which is something we've never seen before. Here's a list of questions that we don't know the answers to:

It's possible that the clouds will come and go, or that we might always have a cloud of variants that constantly changes (like a ship of Theseus), or that this might be it, or that something completely different comes along after all the Omicron strain. We have no idea which way it will go. We could have a completely new variant (Pi or Rho) or see ping-pong zoonosis as viruses move back and forth with other species, which has already happened with deer, and we've seen Covid in large cats and other primates. And Covid could recombine with other corona viruses, like MERS, which is a very deadly version (like at the World Cup). 

What can we do? We have to mitigate transmission as much as possible. Boosters don't stop transmission. We need fewer people to get infections in order to get fewer mutations. Masks with N95s worn correctly and cleaning the air (ventilation, filtration, and UV) are variant-proof; they don't have to be catered to specific variants. 

At the very least, we need to stop doing this:

We have to take seriously that the pandemic is not over. It's still evolving, and we need to deal with it. There are 600 variants within Omicron, and some are worth watching. In China, BF.7, minotaur, is increasing because they're undervaxed, and it transmits quickly. In Ontario, BA.5 was causing the most problems, but now BQs are taking off. 

Public Health messaging that this will be the last variant reveals that they don't understand evolution. There are two reasons for this: 1. There's a tendency to focus on what your'e accustom to and what we've seen before, and some argued that corona viruses don't do this and that, but this one does! 2. There's a phobia of panic in public health. e.g. Don't call it SARS because it's too scary. But panic is not the worst thing in a crisis. Fear is a healthy response when there's a threat. 

Finally, a bit about immunity debt (see this piece co-authored by him for more details)

There are two different things being described by immunity debt. It's a brand new term to 2021, not an established concept. First, that immunity is like a muscle to work out. This is absolute nonsense - a twist of the old hygiene hypothesis to expose kids to microbes. Let kids play in the dirt, but don't let them run around a biohazard lab. It's just not true, and it doesn't make any sense to get sick in order to avoid getting sick. 

The other sense of the term is trivially true - that if you have a population that hasn't been exposed to a virus that they normally might be, then there will be more hosts available to get it later, and you end up with a double cohort. But even if we accept that as trivially true, is that accounting for what we're seeing? Is the massive increase in the death from strep and cases of scarlet fever due to lockdowns and masks? It hasn't been tested or any hypothesis formulated clearly; it's just a narrative that fits with people's understanding. Is it true that there was no RSV for two years? No, there was lots of it last year in Canada and Sweden. There is no longterm immunity to strep, which is bacterial, so that can't be understood by this theory. Also, schools weren't closed for two years. Ontario closed for the longest, but just 20 weeks. Quebec closed for just 9 weeks, which is shorter than summer, and Sweden didn't close at all, so you'd expect to see more in Ontario, than Quebec, and none in Sweden, but we're not seeing that at all. 

[ETA: he pinned a tweet Dec. 17 that clarifies, "I'm not saying the trivially true version of "immunity debt" is not involved (it surely is, but that's a terrible name for it). I'm saying we need to seriously consider the *potential* additional impact of most kids being infected with COVID over the past year."] 

There are other hypotheses that make a lot more sense, that co-infection between Covid and the flu and/or RSV can make it much worse, and that Covid weakens the immune system. Like other viruses (e.g. measles), Covid makes the host more susceptible to other diseases. It runs down the body so it can't fight off another virus later. If that's true, then it's not a matter of riding out this year. It means things could get much worse and kids will be harmed much more by any viral, bacterial, or even fungal infections. There are also hindering factors. Studies are showing that infection during pregnancy affects lung development of the fetus, which could have implications for those children. 

We have to stop assuming we've got a solid handle on this virus. It's changing a lot! We haven't really tried a solid strategy of distributing N95s and teaching people how to wear them and the importance of wearing them properly all the time. (NO pulling them down to talk!!) There are layers of impact now: antibiotic shortages and rising cases in China will affect everyone here. Things will be very bad in January, so maybe let's mandate masks for a few weeks. We insist on clean water; we should be insisting on clean air. How severe does it have to get for people to recognize that we need to work together to do something?

"I don't argue for zero Covid, but for less Covid than this!"