March 19, 2024

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Science It Works

Opinion: The logic behind vaccine mandates for travellers no longer holds

Zain Chagla is an infectious diseases physician and an associate professor at McMaster University.

There should be no doubt: Vaccines are important in the fight against COVID-19. I wholeheartedly believe individuals should be vaccinated to protect against severe complications. I have put in hundreds of volunteer hours to make sure that evidence-based communication is brought to communities, both locally and internationally. And as someone who also works in travel medicine, I expect that making sure vaccines are up-to-date, including the COVID-19 vaccine, to be part of normal counselling.

But medicine is about recognizing what does and does not make sense based on the prevailing science. That’s why, in February, I questioned the paradigm that existed around stringent global testing and travel restrictions. And while there has been a significant transition away from those measures, we need to bring down the other limits to individual rights that don’t make medical sense. This is why we should reconsider our mandate requiring full vaccination for Canadians boarding a commercial plane or train for travel to domestic and international destinations.

The justification behind vaccine mandates is that they help prevent transmission. But this does not seem to be the case any longer, with the Omicron variant. We know that vaccine efficacy in this regard wanes significantly: Data from the UK Health Security Agency shows the effectiveness of two or three doses of vaccine against spreading the Omicron-variant infection over time approaches zero.

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In Canada, the requirements to be deemed fully vaccinated include several World Health Organization-approved vaccines that have even lower efficacy than mRNA vaccines. Furthermore, the efficacy of a prior infection against reinfection approaches that of two doses of vaccines; since many unvaccinated individuals have likely been infected, they may now have a similar level of immunity to their vaccinated peers. Additionally, since Canadians under the age of 12 are not currently required to be vaccinated, unvaccinated individuals have effectively been a part of travel all along – meaning that environments of exclusively vaccinated individuals do not exist. So current mandates are only creating environments in which people who can transmit the virus are alongside people who can transmit the virus, with minimal extra protection.

The current vaccines do offer significant protection against severe disease or hospitalization and, certainly, individuals who are vaccinated are at a much lower risk of adverse outcomes. Some may see this as a reason to consider a proof-of-vaccination mandate for travel. But this minimizes the gradient of risk around age: A triple-vaccinated 70-year-old with diabetes, for instance, would still have a higher risk of hospitalization than an unvaccinated 30-year-old. Of course, discriminating against the ability to travel based on age would be unethical. So wouldn’t discriminating based on risk of severe disease be unethical, too?

There has also been an argument that such mandates would incentivize vaccine uptake. However, the percentage of adults who have become fully vaccinated since Nov. 30, 2021, when the proof-of-vaccination became mandatory, has only increased by about 3 per cent.

While lifting the mandate may seem unfair to those who were vaccinated, there are real equity issues with keeping it on the books. Many individuals may not be able to access essential life events, visit family or friends, or engage in employment opportunities, because of these regulations. While we may have beliefs around vaccination, denying an individual the ability to say goodbye at a funeral is not a part of our values as Canadians. If arriving from an international destination, an unvaccinated 12-year-old who had a prior infection would have to go into quarantine for 14 days and undergo repeated testing because of the current rules, when in reality they present little threat to their community.

Enforcing the mandate is not cost-neutral, either. The 2022-2023 Canadian budget allots $25-million to the maintenance of the ArriveCan app, as well as to the cost of testing and the enforcement of border measures. These funds could instead go toward improving safety in transit in other ways. For example, improving staffing at airports to alleviate prolonged lineups in tightly enclosed spaces may reduce the risk of COVID-19 transmission far more than ensuring all travellers are vaccinated.

This is not a partisan issue. All levels of government took drastic steps in an unprecedented crisis in order to protect the health and safety of Canadians, including around travel, and they should all be praised for the actions taken to protect lives and navigate an uncertain time. But as the science evolves, so too should our response. That’s how we can ensure public trust is maintained moving ahead.

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