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Update IV, Sat April 10th: The paper, mentioned as a pre-print in the original post, from the German group that originally described the issue has now been peer-reviewed and published in the New England Journal of Medicine...Here....A companion paper that comes, essentially, to the same conclusions from a Norwegian group is...Here.
...The United Kingdom has officially reported only 5 cases—despite administering 11 million doses of the AstraZeneca vaccine...
Compared to, for example, Norway:
...Norway, which has administered the AstraZeneca vaccine to 130,000 people under 65, has reported five patients who had low platelets, hemorrhage, and widespread thromboses, three of whom died...
Why the difference?
...So far, most cases have been observed in women under 65. But that could be because of the vaccinated population: Many countries initially used AstraZeneca only in people under 65 because early clinical trials included few older recipients. That meant the vaccine was used in priority groups such as health care workers and teachers, a majority of whom are women. In Norway, for example, 78% of the AstraZeneca doses went to women, says Sara Viksmoen Watle, chief physician at the Norway Institute of Public Health. The United Kingdom, however, used the vaccine first in older people, which may explain why fewer unusual clotting events have been spotted there...
So, can this problem be dealt with?
...Greinacher agrees on the need for more data. But he says it's crucial to alert doctors to the potential complication. When recognized in time, HIT can be treated with immunoglobulins—nonspecific antibodies from blood donors—that help put the brakes on platelet activation. Non-heparin blood thinners can help dissolve the clots. VIPIT should be treated in a similar way, he says. In at least one case, Greinacher says, a doctor sought the group’s advice and the patient recovered...
The work of the German group has not yet been peer-reviewed, but they have placed the data on a public pre-print server so that it can be scrutinized by experts in the field. And, at the very least, the British Society for Hematology and the German Society for the Study of Thombosis and Hemostasis (of which Dr. Greinarcher is a member) are taking the matter very seriously and issuing guidelines for monitoring and potentially treating the issue. In addition, the European Medicines Agency is having a very close look at all the data and it is expected to report on the matter next week (Apr 6-9th).
...Many countries are, for now, accepting the risk that the AstraZeneca may carry, but several have restricted its use to people who are at the highest risk of dying from COVID-19: those aged 55 or older in France, 65 or older in Sweden and Finland, and 70 or older in Iceland...
It would appear that Canada's decision to do the same, despite the fact that no cases this disorder have yet been detected after the administration of 300,000 doses of the AZ vaccine nationally, is, at least for the moment, a prudent one, particularly given that we have other vaccines at hand.