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Sep 14, 2021 01:06PM
Sep 14, 2021 01:19PM
"I'm not sure of the issue with the vaccines coming from manufacturing plants in Europe - with any multinational company, products can come from any of their facilities on a supply/demand basis. Considering the U.S. has a vastly larger population than Canada, why wouldn't it make sense for local products to be used in the U.S. first, as long as the European facilities could keep up the supplies needed to other countries?"
No, it wouldn't make sense, not if the American plants were designated within Pfizer and Moderna as being the supply sources for Canada. The American plants were built with capacity to supply the U.S., Canada, and maybe Mexico and some Latin American countries. The mandate by Trump/Biden put extra pressure on the EU sites, which were not supposed to be supplying Canada (and possibly these other countries) and couldn't keep up. Early on - February, March, April, even into May - Canada and many EU countries were significantly behind the U.S. in % vaccinated because of lack of supply. At a time when only those 65+ could get vaccines in Canada and many places in Europe, the U.S. had enough supply to open up vaccinations to all ages (of course, since they had all the vaccine production that should have gone to Canada and other countries normally supplied by the U.S. plants), and they were flooding drugstores with supply. I would watch the U.S. evening news every night with steam coming out of my ears.
wrenn, yes, the reason that Canada's vaccination rate eventually (in May/June) jumped past other countries was the decision to give out as many first doses as possible before starting in on second doses. To be honest, I think that worked in our favour. From my reading, it's my understanding that a 3-4 month window between vaccine doses is generally believed to be optimal. With the Pfizer and Moderna vaccines, the recommended interval between doses was much shorter, but this was driven solely by the fact that they were rushing to market; in the clinical trials, to save time, they only tested the shorter interval. AstraZeneca did test both 4 week and 12 week 2nd dose intervals in their clinical trial, and 12 weeks was far superior. I seem to recall reading recently that a trial result came out on Pfizer at 12 weeks, and the results were improved versus having the 2 doses at the shorter (and officially recommended) interval. So despite not having specific information about Pfizer and Moderna vaccines, Canadian officials made their decision to delay second doses based on a lot of vaccine history. With AstraZeneca, they made the decision on 12 weeks for second doses based on the AZ clinical trial results.
I don't know this for fact, but I suspect that part of the reason why the efficacy of the vaccines is fading so fast in Israel and U.S., both countries where they got 2nd doses into people quickly, is because those second doses were given at 3-4 weeks, versus a more optimal extended timeframe.
Despite the major mess-up that was the vaccine roll-out in Canada, in the end I think I got lucky. At a time when only those 80+ could get a Pfizer or Moderna vaccine in Ontario, AstraZeneca (which did not have enough seniors in their clinical trial) was made available to those aged 60-65. That allowed me to jump the line and get my first dose sooner. 12 weeks later, by the time I was eligible for my second dose, I had the choice of AZ, Pfizer or Moderna. Based on several clinical trials that found that AZ followed by Pfizer was more efficacious than 2 doses of AZ or 2 doses of Pfizer, I opted for Pfizer as my second dose. Mixed doses appear to be better than 2 doses of the same. Check. 12 weeks between doses appears to be better than 3-4 weeks. Check. A double win for me, but only after a lot of frustration, thanks to the supply issues and very slow roll-out.
Edited to add: SerenitySTAT, I had not seen that study. Very interesting. It appears that they are saying that the interval should be "at least" 9 weeks, with delays of anywhere from 9 weeks to 15 weeks being optimum. This is consistent with my earlier reading about intervals on other types of vaccines.
Dx 9/15/2005 Right, 7cm+, DCIS-Mi, Stage IA, Gr 3, 0/3 nodes, ER+/PR- ** Dx 01/16/2019 Left, 8mm, IDC, Stage IA, Gr 2, 0/3 nodes, ER+/PR-, HER2- (FISH) ** Surgery 11/30/2005 MX Right, 03/06/2019 MX Left ** Hormonal Therapy 05/2019 Letrozole