The noose is tightening on China. Alerted by the wave of infections that is sweeping this country, the United States and several countries are again imposing tests on arriving travelers. Should Canada follow suit? Benoît Barbeau, professor in the department of biological sciences at UQAM and Nathalie Grandvaux, virologist and researcher in biochemistry at the Center hospitalier de l’université de Montréal (CHUM), answer questions from the Homework.
The United States has just joined countries imposing new tests on travelers from China. Is it a good idea ?
Nathalie Grandvaux : Yes, I believe that Canada must consider this option very quickly. We have always been behind in the transmission of new variants. I believe it is very important to know when they arrive so that we can adjust our own sanitary measures accordingly.
Benoit Barbeau : Doing PCR tests on arrival, given the significant resurgence observed in China, it is not a bad idea. I don’t see any downside to that. On the other hand, imposing a quarantine would be an excessive measure. We have seen that it was a very cumbersome measure from an administrative point of view and partially effective, because it was sometimes not respected.
How would such tests be useful today?
BB : We now have very good expertise in screening [du génome du virus de la COVID]. We would at least know which variants are in circulation in China and the percentage of positivity among travelers screened. Provinces and cities in Canada have large Chinese communities, likely to travel or return from China. I believe that we must be vigilant in the face of the announced resumption of travel by China.
Airport screening hasn’t stopped variants like Delta or Omicron from getting into Canada before, why would it allow it now?
BB: Variants cannot be prevented from circulating because travelers from other countries can also introduce them. Moreover, the restrictions imposed on South Africa did not block the entry of Omicron. There is always a limit to what you can do to limit the spread of new variants and subvariants.
NG : In the case of Omicron, however, we were fortunate to have very early data on the existence and properties of this variant from South Africa.
So what would be the advantage of generalized screening of travelers from China at airports?
BB : The usefulness would be more to slow down or delay the arrival of a new variant, not to prevent it from crossing our borders. Because if too many infected people enter the country and infect others, right now, when our health system is already overloaded at the start of winter, it could have an effect on a next wave.
Should we be worried about the wave of COVID in China?
NG : China’s transparency cannot be relied upon at present. Nobody has the precise portrait at the moment of the situation. But after enforcing the zero COVID policy since March 2020, China has not planned a way out. They stopped testing. The official figures show 7 deaths since December, but on a strictly biological level, it is impossible. All we can do is try to get as much information as possible and sequence [les tests] of all the people coming out of China right now.
BB : There is no full transparency at the data level, but the situation seems worrying. Of course, this resurgence is important, but we seem to be dealing at the moment with sub-variants, such as BF.7, which we have already identified here. Like us, China faces multiple Omicron sub-variants. But as the virus circulates there extensively, there is now a greater risk of the emergence of new variants.
Are Canada and Quebec better prepared than China to deal with a possible emerging variant?
BB: Our situation is very different from theirs, as the Chinese have little hybrid immunity, with very few people having been exposed to the virus (due to the restrictive measures). Their vaccine seems less effective against Omicron subvariants, especially for vulnerable people. We have lived through three years of pandemic with another vaccine reality and many more people infected. Our collective immunity is therefore stronger.
Is the arrival of a variant capable of thwarting our immunity still possible?
NG : With 1.4 billion people in China, at the rate this virus is now spreading in an undervaccinated population, there is a high probability of new variants emerging. We see that the hospitals are overwhelmed, but we do not know if it is linked to the collective immunity deficit or to a variant causing more damage.
BB : Omicron has set the bar so high in terms of ease of transmission, it’s hard to imagine. This is all just speculation at the moment. We cannot predict whether the virus will mutate so that it is even more contagious or more dangerous. Better to be more careful than not enough, and to advocate a less restrictive approach than quarantine, but more effective.
Is Canada erring in contenting itself with “monitoring the situation”?
N.G. : We are supposed to have learned from the last 3 years. It cannot be ignored how quickly variants spread. We are in exactly a similar situation to Christmas 2021 where Omicron had just arrived, at the same time as a resurgence. And we have seen what happened with more deaths in 2022 than in 2021. The Schengen area is evaluating the possibility of testing all travelers coming from China. I would say don’t think too long. In 15 days, it will be too late. If we want to act, we have to act in time.