Complete border closures have slowed the transmission of COVID-19

Complete border closures have slowed the transmission of COVID-19

Complete border closures have slowed the transmission of COVID-19

Valérian Mazataud Archives Le Devoir On a global scale, “the total closure (of borders) slows down global and internal transmission”, concludes the study. In stark contrast, “we haven’t seen any significant declines (in spread) for targeted shutdowns globally.”

Closing borders to all foreign travelers will have “significantly slowed” the spread of COVID-19, unlike partial closures targeting countries where outbreaks were reported, a measure that has had little or no effect.< /p>

This is the main conclusion reached by researchers from York University, Toronto, who analyzed the effects of comprehensive and targeted shutdowns during the first wave of the pandemic in February and March 2020.

The results of the study vary depending on whether we are analyzing the spread on a global or domestic scale in countries that have closed their borders completely or partially and on the countries themselves, said the principal researcher, Mathieu Poirier, during an interview with The Canadian Press.

Assistant professor of social epidemiology and holder of the institution's Global Health Equity Research Chair, Mr. Poirier points out, however, that the results, published Monday in the journal PLOS Global Health, are conclusive overall, although 'they require important nuances.

Total closure vs. targeted closure

His team analyzed available information from 166 countries to compare coronavirus transmission data before and after the partial and full shutdown to that of countries whose borders had remained open. Globally, “total closure (of borders) is slowing global and domestic transmission,” he concludes.

In contrast, “we haven't seen any significant declines (in the spread ) for targeted shutdowns globally.

Results at the domestic level, i.e. within countries, vary slightly, however. We note that both total and partial closures had an impact on reducing the spread, but that total closures were more effective.

Partial shutdowns, on the other hand, were effective when implemented early and targeted more countries: “Targeting more countries has proven more effective than just targeting higher-risk countries. . In other words, the logic holds: the wider the border closure, the more effective it is.

The researchers' work confirmed a reality already observed in the past, says Professor Poirier: “It was not the first time that we tried to target countries and it was not the first time that we found that it was not effective. »

Incorrect targeting

The reason, he says, is very simple: what you think you know is usually not the reality. “Even if you think you know where there's a hotspot or an outbreak going on, it's very likely that it's also happening in other countries where it's not as obvious, where you reports less well (epidemiological data). This is exactly what has been seen in the shutdowns targeting southern African countries with Omicron. »

Moreover, he adds, this targeting, in addition to being ineffective, is harmful: “I want to emphasize that the targeted shutdowns were not only less effective domestically and globally, but they punish countries that openly and transparently report outbreaks and that this can lead to a less effective and slower global response to this kind of threat. It can also have real economic and social consequences for the targeted country. »

Effective in Canada

Canada is no exception to the rule, but Mathieu Poirier points out that Ottawa was quick to transition to complete sealing: “Canada has experienced a rapid transition from targeted countries to total closure. The total shutdown implemented in Canada was followed by a significant reduction in the transmission of COVID. “

In any case, it should be noted that the researchers do not give precise figures on this reduction: “Our level of confidence is not high enough to go so far as to quantify these reductions. On the other hand, it is very high when it comes to asserting that these are significant reductions. »

However, even if a country implements a total shutdown, “it might have no effect because it's not strict enough, that by bad luck international traffic comes in anyway, that the country can't afford screening or implementing appropriate public health measures.

A total closure, “it's not a guarantee”, he warns.

Legal closures or not?

< p>The study also raises, without however resolving it, the question of the legality of these border closures, partial or total. Although countries are sovereign in controlling their borders, a pandemic refers decisions that have international implications to the International Health Regulations (IHR) which are legally binding on the World Health Organization (WHO) and 196 countries, including Canada.

One of the principles of the IHR is that a measure should not be more restrictive than necessary and that decisions should be based on science. However, argues the researcher, “with a pandemic that is spreading so quickly, we do not have reliable information when making these decisions. And in this case, he adds, at the time of closing the borders, “there was no scientific data to say whether these closures worked or not. »

Other options

According to Mathieu Poirier, it is not at all impossible, precisely, that these closures were illegal under the IHR: “There were better options for several countries, although the complete closures were effective, as we know now.

Some countries, for example, could have imposed strict quarantines and other heavy-handed internal public health measures to control transmission just as well as shutdown. “It would have been less disruptive and, therefore, a better measure. »

At the same time, he says, there are countries that have been able to benefit from the additional time offered by the slower spread caused by a total shutdown, including countries with less international traffic and fewer resources to fight domestic spread. effectively: “There are definitely benefits to getting more time to prepare internally. »

A gray area

International discussions are underway to try to refine the laws governing these decisions, particularly on the basis of data such as those provided by York University researchers. “We need to build this data so that in the future countries can say: according to the available science, there are certain situations where closing the border is legal and defensible. “

However, like everything else about COVID-19, the virus that scientists are still struggling to understand, the legal aspects also give experts a hard time: “The legality changes depending on the science. It was a gray area and it continues to be a gray area,” sighs the researcher.