Arguments against introducing stricter travel-related measures in Canada during the COVID-19 pandemic often point to data that suggests relatively few cases are traveler-related
This article, written by Kelley Lee, Simon Fraser University and Anne-Marie Nicol, Simon Fraser University, originally appeared on The Conversation and was republished here with permission:
Prime Minister Justin Trudeau recently announced new travel restrictions, as well as COVID-19 testing and quarantine rules, to limit the spread of coronavirus.
Arguments against introducing stricter travel-related measures in Canada during the COVID-19 pandemic often point to data suggesting that relatively few cases are traveler-related. The main source of this data is the Canadian Public Health Authority (PHAC), which regularly reports on locations in Canada that may be exposed to the virus, including domestic and international flights.
Based on these reported exposures, PHAC estimates that international travel accounted for between 0.4 percent in May and 2.7 percent in July 2020 of all confirmed cases in the past eight months. These estimates are then regularly quoted in the media by industry, public health and government officials.
Based on this data, which suggests that the risk of travel is low, governments have hesitated to take tighter measures on who travels and what protocols to follow.
For example, British Columbia’s Prime Minister John Horgan defended his decision on January 21st not to restrict inter-provincial travel on the grounds that the government can only act “if it is concerned about the health and safety of British Columbians damage. If we see transmission increase, we will not impose tighter restrictions on essential travelers. “
Our international team is analyzing decision-making on the application of travel-related measures during the COVID-19 pandemic in different countries including Canada. When we compare Canada’s travel-related policies with other countries and the methods used to detect and count imported infections, we argue that frequently cited numbers are likely to underrepresent travel-related COVID-19 cases. The current system does not systematically or rigorously collect enough data to form the basis for comprehensive policy decisions.
This comes at a time when new COVID-19 flavors are making solid travel policies even more critical. A more robust, timely, and accurate system is urgently needed.
Counting cases
Current estimates are based on international travelers arriving by plane. Passengers must quarantine themselves for 14 days and self-monitor and, if symptomatic, be tested. If they test positive and say they were on an international or domestic flight, an alert will be added to an online list of potential exposures.
Passengers in nearby rows of seats are at higher risk and can be notified. All other travelers are expected to review and quarantine warnings regardless. Only direct cases with passengers are counted. Any subsequent community broadcast by traced or otherwise tracked travelers will not be officially counted.
There is no routine testing or contact tracing of travelers entering Canada. The current data only includes self-identifying symptomatic air travelers who tested positive. Land and sea travelers and air travelers who are infected but untested or asymptomatic are not. And no data is collected on travel between provinces in excess of the exposures observed on domestic flights.
The current methods also make questionable assumptions about the reliability of testing, contact tracing, and quarantine. Over time, multiple tests are often needed to confirm infection. There are many false negatives out there, and new variations prove to be particularly elusive. There is not enough capacity to track all travelers with the current volume.
It is assumed that all international arrivals adhere to the mandatory 14-day quarantine. However, with limited enforcement, some, if any, arrivals may not be quarantined for all of the time.
Countless cases
When measuring travel-related infections, there is a narrow focus on virus transmission in airplanes. In November 2020, Chief Public Health Officer Theresa Tam said, citing the latest research, “There have been very few reports, extremely rare reports of transmission on board aircraft.”
However, many of the studies reporting a low risk of catching the coronavirus on a flight are sponsored by the aviation industry, raising concerns about potential conflicts of interest. What is important is that these studies overlook the risk of infection on an entire trip.
As of January 7, anyone flying to Canada from another country has to present a negative molecular test result (within 72 hours of travel) to reduce the number of coronavirus positive travelers. While this helps, it ignores exposures that occur during the three days between the test and the actual trip.
Then there is travel to and from airports. For example, taxi drivers at the airport have contracted the virus from travelers. Many international passengers take connecting domestic flights without isolation upon first entry, “unless there are provincial or territorial restrictions”. These passengers will also pass through airports before making connecting flights with domestic passengers. Non-flight infections associated with these scenarios are not currently counted.
Make travel safer
Travel and the COVID-19 pandemic are closely linked. The virus was originally imported into Canada while traveling and new infections continue to be brought in every day. This includes COVID-19 variants.
Despite the current partial data, PHAC reported more than 160 international flights and 90 domestic flights with confirmed positive COVID-19 cases between January 7 and 17. These cases have occurred despite new testing requirements.
If we are to make effective policy decisions about managing travel and COVID-19, we need far better data. The current tracking system is overwhelmed, so expanding data collection is a challenge. Reducing the number to key travelers is an important starting point.
Resources can then be focused on improved testing, contact tracing, and quarantine. Random samples could be used to estimate infections by number of travelers at different entry points, modes of transport, and points along a trip. Starting up and splitting the genomic sequences of positive results is then important to identify imported cases of new variants more thoroughly and more quickly.
Only then can we get a precise feel for travel-related risks and how best to address them.
Kelley Lee, Professor of Global Health Policy, Canadian Research Chair in Global Health Governance, Simon Fraser University and Anne-Marie Nicol, Associate Professor, Health Sciences, Simon Fraser University
This article is republished by The conversation under a Creative Commons license. read this original article.
