Hello, everyone, and good morning. Thanks for allowing me to appear as a witness for the Standing Committee on International Trade's study of the potential impacts of the ArriveCAN application on certain Canadian sectors.
My name is Zain Chagla. I'm an infectious disease physician, medical director of infection control at St. Joseph's and an associate professor at McMaster University, both in Hamilton, Ontario.
Throughout the pandemic, I've worked with COVID-19 infection control, vaccinations, therapeutics, local epidemiology, clinical trials and public education. I'm a frontline physician and still see up to 50 patients a week with COVID-19 to offer them early therapy.
Today's meeting focuses on the impact of ArriveCAN. My focus today is not on the application per se, but why the measures instilled in ArriveCAN were needed and when the need for them started to decrease. This is important because the need for the application was predicated on the need for certain travel measures throughout the pandemic.
Canada has used several travel measures, including pre- and post-arrival testing, quarantine of various groups and proof of vaccination when vaccinations became available. At the beginning of the pandemic, it was increasingly apparent that international travel was leading to ongoing transmission within Canada, whether it was through international flights or the land border with the United States. In the first year of the pandemic, with fairly limited options to reduce transmission, the subsequent health care utilization and the background of ongoing local restrictions to limit transmission, the use of these travel measures did make sense. However, following the introduction of vaccinations, the data suggested a marked reduction in transmission and infection and a significant decrease in severe complications in vaccinated individuals, marking a time when the long-term sustainability of vaccinations and eventual therapeutics may have led to a rethink of pandemic measures.
Particularly when omicron emerged, many things changed. Vaccination efficacy still remained quite high with severe disease, but with two doses it decreased significantly. Data from Ontario suggested very limited protection 20-plus weeks after the vaccine dose was administered, which really impacted the use of the proof of vaccination policy to limit transmission associated with travel. One could argue that such a mandate was important to reduce severe disease in travellers, as the vaccines still remain an important measure for that, but we know that the distribution of severe disease is uneven. An unvaccinated 12-year-old still presents a significantly lower risk of hospitalization than a fully vaccinated 80-year-old with available boosters.
Adding to this, the use of quarantine and border measures was also challenged. PCR testing, which was used earlier in the pandemic, is expensive and carries the risk of identifying low-risk or asymptomatic individuals with a prior infection, as they may shed non-viable virus for weeks and even months after infection. This became magnified in the era of omicron, particularly when many provinces limited access to PCR testing for the general public. Many individuals may not have been able to document their prior infection with a PCR test, thereby increasing the risk that an individual identified for random testing will test positive and have to undergo quarantine while posing no threat to the local community.
The use of random testing for variants was important as a secondary benefit, but there were other methods of surveillance, with the ability to do local surveillance and sequencing to improve our variant maps across the country. There was also global data sharing, which allowed for many countries to share data transparently, underlying again the collaboration that allowed us to examine variants of concern without using the international border as a method to do that. The reality is that all variants of concern eventually did reach Canada, with the omicron subvariants currently circulating.
Finally, the use of quarantine in asymptomatic individuals in the omicron era in the context of wide-scale community transmission was really of limited community benefit, recognizing that chains of transmissions were far more likely to occur domestically than they were with international travel or travel over an international border. The lack of benefit was also magnified over the land border, where shorter and same-day travel with personal vehicles coming from a single country with very transparent access to variant data lowered the rationale for employing these measures at the land border.
A modelling study by IATA looked at what the impact of testing and quarantine measures would be in a number of different scenarios, such as an omicron emergence or a vaccine emergence. Across a number of different modelling scenarios, they saw a delay in the peak of infections of two to four days, with largely the same peak of infections noted in local communities. So yes, these measures, if instituted appropriately and at 100%, may work, but all they may do is delay the peak—not necessarily delay the number of infections but delay when they occur and—