COVID-19 safety in schools, Fall 2021

This is my presentation to the special OCDSB meeting Aug. 24, 2021 about the upcoming school year and COVID-related safety and prevention measures.

Background notes, supporting evidence, references, images, and links are below the presentation text.


I appreciate the opportunity to address this meeting. I’m a former OCDSB student and teacher, and have also volunteered for class visits on media literacy, Indigenous solidarity, and sexual health education. My degree in mathematics affords a literacy of much of the COVID research.

1) Last school year, I was concerned and angered with many high-profile local health professionals’ statement in news media and on social media about how safe schools were.

In June, I published a mathematical analysis of Ottawa Public Health’s report on COVID in schools, illustrating that there were likely many more cases in schools, and much more in-school transmission, than OPH reported.

It is too long to get into here, but a large problem was a lack of robust testing to identify cases.

Research suggests that regular systematic ‘screening’ testing is most helpful.  Economic limitations may mean that systematic environmental testing – of air and surfaces – is the most viable option.

Identifying a greater proportion of cases, early, is an important strategy to figure out and implement.

2) I’ve provided a graphic based on the work of some COVID researchers, that depicts a full complement of school safety and prevention measures to implement  I hope that everyone in the board in a position to implement any of these measures, are made aware of them.

3) One particular measure I’d like to specifically address is ventilation. ‘Opening windows’ is almost treated as an afterthought in the provincial guidelines; however there is research suggesting it can be almost twice as effective as the air filtration systems. I hope this will be prioritized as much as possible.

4) And on mandatory vaccinations.

I think it is somewhat authoritarian to be forcing vaccinations on people.

There has been misleading public messaging – last week, Dr. Etches was in the news about how unvaccinated people are 20x as likely to get infected as fully-vaccinated.

But research posted by the US CDC suggests approximately 75% vaccine effectiveness against Delta infection, not Dr. Etches’ 95% (20x) but  4x.

And fully vaccinated people who get infected, are almost as infectious to others as unvaccinated people are.

Yesterday [August 23], the organizer of Sunday’s ‘#SafetyPalooza’ was on CBC radio promoting mandatory vaccinations: “What are [unvaccinated kids] to do if they go into a school and they have a teacher who’s not vaccinated, or if they get on a school bus and that school bus driver isn’t vaccinated?”

To me that sounds like talk about ‘the Big Bad Wolf’ or  bogeyman, and ignores the much larger risk of transmission from the other students, as well as the risky activities permitted in the provincial school guidelines.

 I note some unions have been speaking of protecting their members’ rights against such enforced vaccinations. I don’t think ‘majority-rule’ or popular opinion is the best way to decide such issues, nor is automatically de-legitimization of differing positions.

I very much recommend that no decision be made until the deciders are able to at least communicate an understanding of the major concerns around vaccine mandates – including people’s rights, longer-term thinking around antibodies, boosters, and variants, and other issues that I’m not an expert on.

I have posted the text draft of this presentation – along with supporting references and resources – at my website,


COVID spread in schools: Ottawa Public Health conclusions differ from data
My in-depth analysis of OPH report on COVID in schools, published in June.
The four main areas:

  • No systemic attempt to find asymptomatic cases – and youth are recognized to have higher asymptomatic rates than other ages;
  • Lack of knowledge on how effective the procedure to identify school outbreaks actually was;
  • A change in testing guidelines one month into the school year skewed the case counts – and were it not for Ottawa’s unique wastewater levels measurements, we wouldn’t know how much of a skew this was;
  • On top of all the above, OPH simply made the assumption that all school cases not traceable to another infected person, must have been contracted somewhere other than in school.

A highlight = the three graphs that illustrate how at the start of October, the amount of testing dropped in half, and the number of measured school outbreaks that had been rising since the start of the school year, went down … while the actual COVID rate locally (measured in the wastewater levels) shot up – and afterwards, the the two levels still roughly paralleled each other, but with way more distance between them. (You need to see it).

Importance of “rapid universal monitoring”
(systematic testing)

COVID-19 in schools: Mitigating classroom clusters in the context of variable transmission
Research article, 8 July 2021, by Paul Tupper and Caroline Colijn (PLOS Computational Biology)

Research excerpt: “Among the measures we modeled, only rapid universal monitoring (for example by regular, onsite, pooled testing) accomplished this prevention.”

Systematic Environmental Testing (of air and surfaces)

Covid virus spread can be combatted through environmental testing. Why aren’t we doing it?
“Environmental sampling is an unbiased and unambiguous approach to locating where the disease is spreading.” by Dr. Cyrus E. Kuschner, Zarina Brune, and Dr. Lance Becker | NBC, 4 Feb 2021

Recommendations for safer school re-opening (image and research paper):

Reopening schools without strict COVID-19 mitigation measures risks accelerating the pandemic
6 March 2021 | OSFpreprints | AUTHORS: Deepti Gurdasani, Nisreen Alwan, Trisha Greenhalgh, Zoë Hyde, Luke Johnson, Paul Roderick, Susan Michie, Martin McKee, Kimberly A. Prather, Sarah Rasmussen, Stephen Reicher, Hisham Ziauddeen
(Link to tweet of image)

Window ventilation can be more effective than the filters (read paper for details)

SARS-CoV-2 aerosol transmission in schools: the effectiveness of different interventions
20 August  2021 | medRxiv | AUTHORS: Jennifer Villers, Andre Henriques, Serafina Calarco, Markus Rognlien, Nicolas Mounet, James Devine, Gabriella Azzopardi, Philip Elson, Marco Andreini, Nicola Tarocco, Claudia Vassella, Olivia Keiser

False impressions about COVID infection, spread, and vaccination

Dr Etches last week says 20x as likely to get infection if unvaccinated…
but CDC collection of published research on Delta / vaccination effectiveness suggests 75% (aka 4x):

CBC audio for “#SafetyPalooza” coming soon… ((Unvaccinated are the bogeyman?))

Being fully vaccinated can = false sense of security

I went to a party with 14 other vaccinated people; 11 of us got COVID
By Allan Massie | The Baltimore Sun, 3 Aug. 2021
The experience and recommendations from an epidemiologist and biomedical researcher at the Johns Hopkins School of Medicine.

This stuff isn’t all clear cut or simple – are people telling you it is?

.., will add the rest when I have the opportunity, aiming for by mid-Wednesday …

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