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> However, even when community spread was wiped out in the summer of 2020, we would have a few cases imported each day, mostly from the US Is this really the b

> However, even when community spread was wiped out in the summer of 2020, we would have a few cases imported each day, mostly from the US Is this really the belief? Canada’s inferiority complex wrt to the US has made their perception of COVID out of touch with reality. There was always significant community transmission in BC, even in the summer. Cases never went to zero, the lowest point was ~10/day. And it’s likely underestimating by a factor of >5 since testing in Canada was not done well. (This is despite the popular perception. Anecdotally, in Washington my family was able to roll into drive thru testing sites and get next day results for free, and in Canada it was a >$100 appt at the retail pharmacy and 3-5 days for results. I don’t how it is now, but Washington has been doing ~3x as much testing per capita as BC since early summer last year.) So even if essential travelers crossing the border was importing a few cases a day (extremely unlikely IMO, and zero evidence supporting this), it would be accounting for a small single digit percentage of cases.

tempestn 6y ago
BC has not been doing the quantity of testing that WA has, but it had been contact tracing all cases, and in the summer when cases were in the single to low double digits per day, the majority of cases were traced to travel, from the US and from elsewhere in Canada. For a number of weeks there was not significant community spread. You don't need to test the whole population to know that; if case that are found can be contact traced to a travel event, that is sufficient to demonstrate lack of significant community transmission. Of course many of these imported cases did transmit the virus to others locally, but the point was that the sequence of transmission could be traced back to a specific border crossing. As opposed to community spread, where the original source of introduction is unknown. This is based on evidence presented at the time in briefings from the BC public health officer. Do you have any basis for the claim that only a "small single digit percentage of cases" were imported from the US during the summer? Certainly community spread has worsened significantly since then, but that's kind of my point; it was never realistic to essentially eradicate the virus and then open back up here, as NZ did, because there would always be a baseline number of imported cases ready to spark a new outbreak.
- amscanne 6y ago
  I think my point was not well constructed. NZ locked down, had good isolation, and got a bit lucky. The problem with COVID is that because there’s a large portion asymptomatic carriers, the success of contact tracing can vary a lot. In Canada, it is politically expedient to point to (valid) US failings and throw them under the bus. I don’t doubt that this is something done by the BC health officer at the time. My math of single digit percentage is based on even having a few cases a day coming in contrasted with 10-20 cases underrepresented by a factor of ~5. It’s just guessing, but I doubt they have more than a few direct travel cases each day and therefore community transmission was significant. I would be curious if there was any data that suggests this guesstimate is wrong. It’s possible to argue that all that community transmission was the result of border crossings, but the same is true everywhere and quickly becomes non-sensical. Would the virus have disappeared if not reseeded by travel cases? We do know that New Brunswick and Nova Scotia had the same essential travelers (i.e. baseline imports) but were able to effectively control and have had no deaths since August of last year (and very few cases). I’m not saying that BC did a poor job — I’m not sure that BC could have done anything to contain the virus completely. But I also don’t think it’s reasonable to point the finger completely at travelers as the thing that prevented success.
  - tempestn 6y ago
    I'm not saying travelers prevented success, nor that BC's response was perfect. I definitely don't believe that was the case, and could even point to specific decisions I believe were poor, but it would be getting off topic. What I'm saying is, BC's leadership made a conscious choice not to aim for 'COVID zero', due to the fact that there would always be a baseline number of imported cases, so it would never be possible to eliminate the virus to the extent that restrictions could be meaningfully relaxed, as they were in NZ. To me that choice makes sense, although I do feel they took it a bit too far; as cases started really going up over the winter I would have liked to have seen increased measures restricting gathering sooner. But I'm also not operating with all the information they are, so can only second guess so much. As for the Atlantic provinces, they are quite a bit more isolated than BC is, despite, yes, also having a certain amount of necessary traffic. And I agree with you that there's likely some luck involved as well.

tempestn 6y ago

BC has not been doing the quantity of testing that WA has, but it had been contact tracing all cases, and in the summer when cases were in the single to low double digits per day, the majority of cases were traced to travel, from the US and from elsewhere in Canada. For a number of weeks there was not significant community spread. You don't need to test the whole population to know that; if case that are found can be contact traced to a travel event, that is sufficient to demonstrate lack of significant community transmission. Of course many of these imported cases did transmit the virus to others locally, but the point was that the sequence of transmission could be traced back to a specific border crossing. As opposed to community spread, where the original source of introduction is unknown. This is based on evidence presented at the time in briefings from the BC public health officer. Do you have any basis for the claim that only a "small single digit percentage of cases" were imported from the US during the summer? Certainly community spread has worsened significantly since then, but that's kind of my point; it was never realistic to essentially eradicate the virus and then open back up here, as NZ did, because there would always be a baseline number of imported cases ready to spark a new outbreak.

amscanne 6y ago
I think my point was not well constructed. NZ locked down, had good isolation, and got a bit lucky. The problem with COVID is that because there’s a large portion asymptomatic carriers, the success of contact tracing can vary a lot. In Canada, it is politically expedient to point to (valid) US failings and throw them under the bus. I don’t doubt that this is something done by the BC health officer at the time. My math of single digit percentage is based on even having a few cases a day coming in contrasted with 10-20 cases underrepresented by a factor of ~5. It’s just guessing, but I doubt they have more than a few direct travel cases each day and therefore community transmission was significant. I would be curious if there was any data that suggests this guesstimate is wrong. It’s possible to argue that all that community transmission was the result of border crossings, but the same is true everywhere and quickly becomes non-sensical. Would the virus have disappeared if not reseeded by travel cases? We do know that New Brunswick and Nova Scotia had the same essential travelers (i.e. baseline imports) but were able to effectively control and have had no deaths since August of last year (and very few cases). I’m not saying that BC did a poor job — I’m not sure that BC could have done anything to contain the virus completely. But I also don’t think it’s reasonable to point the finger completely at travelers as the thing that prevented success.
- tempestn 6y ago
  I'm not saying travelers prevented success, nor that BC's response was perfect. I definitely don't believe that was the case, and could even point to specific decisions I believe were poor, but it would be getting off topic. What I'm saying is, BC's leadership made a conscious choice not to aim for 'COVID zero', due to the fact that there would always be a baseline number of imported cases, so it would never be possible to eliminate the virus to the extent that restrictions could be meaningfully relaxed, as they were in NZ. To me that choice makes sense, although I do feel they took it a bit too far; as cases started really going up over the winter I would have liked to have seen increased measures restricting gathering sooner. But I'm also not operating with all the information they are, so can only second guess so much. As for the Atlantic provinces, they are quite a bit more isolated than BC is, despite, yes, also having a certain amount of necessary traffic. And I agree with you that there's likely some luck involved as well.