Expert Opinion on How to Protect Against COVID-19 Transmission in Schools

Dr. David Fisman is a world renowned epidemiologist and expert on COVID-19 transmission. His expert opinion was included in the application to the Ontario Labour Relations Board (OLRB) by the four teachers' and education workers' unions seeking a province-wide remedy to the unsafe conditions under which schools have resumed. The OLRB rejected the application for "lack of jurisdiction," thus his opinion was never considered. Workers' Forum is reproducing excerpts from Dr. Fisman's expert opinion below.

Credentials of Expert Witness

Dr. David Fisman: Tenured Professor at the Dalla Lana School of Public Health at the University of Toronto; former Head of the Division of Epidemiology, DLSPH; incoming head of Pandemic Readiness stream at the new University of Toronto Institute for Pandemics; Associate Medical Officer of Health with the City of Hamilton 2001-2003; author of over 200 publications including "15 papers related to the epidemiology of COVID-19" since February 2020; funded by the Canadian Institutes for Health Research (CIHR) for COVID-19 study; recently chaired an international symposium on COVID-19 transmission; and invited speaker at recent (August 4, 2020) World Health Organization symposium on COVID-19 transmission; and "a member of Ontario's Modelling Table and Science Table, both of which advise the Ontario Provincial Government on COVID-19."

How COVID-19 Is Spread

12. "... early in the pandemic, fomite transmissions (i.e. infection that results from physical contact with a contaminated object) was believed to be an important route. ... However, evidence now shows that fomites are a far less significant driver of COVID-19 [than] originally thought."

13. "...aerosols are increasingly recognized as an important mode of transmission of COVID-19 ... This is likely to explain the propensity of COVID-19 to cause large clusters in 'closed, close, crowded' settings including long-term care facilities, food processing plants and homeless shelters."

15. "...Restaurants, bars and other indoor gathering places such as churches have featured prominently in the history of COVID-19 superspreader events."

16. "The fact that large outdoor gatherings ... have not appeared to have driven the spread of COVID is further evidence of the important role aerosols play."

17. "Aerosol transmission may be most likely during the pre-symptomatic phase of infection..."

18. "Asymptomatic infection appears common.... Children aged <10 were three times more likely to be asymptomatic than others."

19. "... children aged 10 and over are as likely as adults to be infected by COVID-19..."

21. "...viral loads in children are similar to, and perhaps higher, than viral loads in adults."

24. "... misconceptions about children and COVID-19 have been driven by the increased likelihood of asymptomatic infection in children (three-fold increased likelihood in Ontario data) ...

Overview of Public Health Measures to Control
the Spread of COVID-19

32. "...best practices globally show that it is possible to reduce COVID-19 transmission to low levels using a combination of distancing, masking, reduced gathering sizes, ventilation and other non-pharmaceutical measures."

36. "Masking is likely most effective as a means of source control: ... masks reduce the risk of both short and long-distance airborne COVID-19 transmission. ... Because it appears that individuals are most infective prior to the onset of symptoms, and many infective people are completely asymptomatic, it is important that masking be done on a universal basis in all indoor locations."

41. "...it has been notable in July and August 2020 that British Columbia has had a rising effective reproduction number... while Ontario and Quebec have gone through a period of low [reproduction numbers] following mask mandates, notwithstanding substantial economic opening in those provinces. ... the relative risk reduction associated with masking orders in Ontario has likely been on the order of 38 per cent in the province as a whole, higher in the Greater Toronto Area ...

42. "... there is no reason to anticipate harms, physical or psychological, from mask wearing in children ..."

43. "...poorly ventilated indoor spaces, crowded places and close contact increase the likelihood that these aerosols infect secondary cases. ... the use of masks is one intervention that helps. ... Another mechanism is increased ventilation ... that is to say removing air inside an enclosed space and replacing it with air from outdoors ..."

45. "Distancing reduces the likelihood of transmission ... distancing is most effective at distances greater than 1.5 meters

46. "... none of these are substitutes for each other. Rather they must all be used simultaneously and consistently in order to effectively reduce the reproduction rate of COVID-19."

Schools and COVID-19

57. "My opinion that unsafe reopening of schools is likely to result in surges in disease that will cause illness and deaths to rise in the community. ..."

58. "It is my opinion that a strong focus on reduced class sizes, improved school ventilation and mask use would help reduce school related surges in COVID-19 activity in Canada this fall.

The Guide to Reopening Ontario's Schools

59. "I have reviewed the Guide to Reopening Ontario's Schools (the Guide). ... The guide does not contain sufficient measures to adequately protect students, teachers and other adults working in schools, or the public more broadly."

60. "... there are at least five major failings in the Guide: the failure to require universal indoor masking at all age levels; the failure to require enhanced ventilation; failing to set out minimum standards for physical distancing; not requiring reduction in class sizes outside of designated secondary school boards; and serious flaws in its approach to cohorting.

64. "Ventilation of indoor spaces is not addressed by the Guide ... Due to the fact that classrooms are closed, close and crowded spaces ... adequate ventilation is key to reducing the risk of infection."

69. "... the Guide does not set out any minimum rules for distancing.

71. "...the Guide does not require schools to reduce class sizes ..."

72. "Reducing class sizes is one of the most effective tools in lowering the risk ... the SickKids Updated Guidance for School Reopening states that "smaller class sizes should be a priority strategy" in reopening of schools. Reducing class sizes produces four distinct forms of protection simultaneously

- ... reduces the probability that any member of a class is infected

- ... reduces the number of secondary cases that could result from a primary case

- ... allows for greater distancing

- ... reduces the overall production of finer aerosols within a fixed indoor space ...

78. "In my opinion, the total absence of class size limits in most classrooms is an unreasonable approach to school reopening from a public health perspective. ... class sizes in the 20s produce significantly higher predicated infection rates than classes half that size."

82. "Cohorting students to a single class, combined with lower class sizes, universal masking, distancing of at least 1.5 meters and adequate ventilation rates constitutes an effective means to ensure that schools do not become drivers of pandemic spread of COVID-19."

84. "...The Guide states that specialized teachers ... will still move from classroom to classroom to provide instruction. This increases the risk of infection to both the teacher, and to the students. We have already experienced a clear example of how this type of movement between cohorts can drive the pandemic in Ontario: the case of long-term care homes.

86. At the high school level, schools are directed ... to keep students to approximately 100 direct and indirect contacts per day and limiting them to two class cohorts. ... Public health guidance directs individuals to maintain social circles of 10, yet the Guide uses contacts ten times that size as a goal.

88. ".... The other strategies that the Guide calls for [hand hygiene, self-screening, goggles and face shields -- WF Ed. note.] are not adequate substitutes for requiring universal masking, implementing physical distancing of 1.5 or more metres, reducing class sizes, requiring adequate ventilation and addressing the shortcomings of the Guide's cohort rules."

(Photos: WF, OSSTF)

This article was published in

Number 72 - October 22, 2020

Article Link:
Expert Opinion on How to Protect Against COVID-19 Transmission in Schools