其 他 安 全 警 示
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| Canada: Summary Safety Review: AstraZeneca COVID-19 Vaccine and COVISHIELD - Assessing the Potential Risk of Thrombosis in combination with Thrombocytopenia (English only) |
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Health Canada announces that it has reviewed the risk of blood clots in combination with low blood platelets following immunization with AstraZeneca COVID-19 Vaccine and COVISHIELD to evaluate emerging information; and determine if further measures are needed to mitigate the risk in Canada. This safety review was initiated after cases of blood clots following immunization with AstraZeneca COVID-19 Vaccine were reported in Europe.
AstraZeneca COVID-19 Vaccine and COVISHIELD are authorized for sale in Canada for active immunization of individuals 18 years of age and over for the prevention of COVID-19. This authorization includes conditions requiring the manufacturer to provide additional information to Health Canada on the vaccine's effectiveness, along with active safety monitoring. AstraZeneca COVID-19 Vaccine is manufactured by AstraZeneca and COVISHIELD is manufactured by Serum Institute of India. Health Canada reviewed the manufacturing information for these vaccines and found them to be comparable, which means individuals could complete the vaccination course with either AstraZeneca COVID-19 Vaccine or COVISHIELD.
Health Canada reviewed the available information from searches of the Canada Vigilance database, international databases, and information received from the manufacturers and international regulators. At the time of the review, Health Canada was aware of one report of a Canadian vaccine recipient who experienced blood clots with low platelets following immunization with COVISHIELD. The review considered all currently available information which included information submitted by the manufacturers in response to terms and conditions that were put in place. Health Canada also reviewed information shared by international regulators, including their assessment of the reports received in their jurisdictions. A link between these events and AstraZeneca COVID-19 Vaccine and COVISHIELD was considered possible. Health Canada's findings are in line with the conclusions of international regulators.
The potential risk of blood clots with low platelets is very rare. As of 31 March 2021, the United Kingdom Medicines and Healthcare Products Regulatory Agency estimated the overall risk of these blood clots to be approximately 4 people in a million who receive the vaccine. Reported cases of these adverse events have been seen after the first dose, usually within the first 14 days after immunization.
The review by Health Canada of available information from Europe, the United Kingdom and the manufacturers did not identify any specific risk factors, such as age or gender for these events. It is recognized that the benefit versus risk of receiving the vaccine may vary by age due to differences in the risk of severe disease associated with COVID-19 illness, which continues to change as the nature of the pandemic changes. A potential mechanism for the combination of blood clots with low platelets is the triggering of an immune response by the vaccine, leading to a condition similar to heparin-induced thrombocytopenia seen sometimes in patients treated with the blood thinner medication heparin. It concluded that a link between the use of AstraZeneca COVID-19 Vaccine and COVISHIELD and the risk of blood clots with low platelets is possible. The risk of these events is very rare. The benefits of AstraZeneca COVID-19 Vaccine and COVISHIELD in preventing COVID-19 continue to outweigh the risk of very rare events of blood clots in combination with low platelets.
The review finds that at this time the information provided by the manufacturers demonstrate the potential benefits of the vaccine across all age groups. Health Canada has worked with the manufacturers of AstraZeneca COVID-19 Vaccine and COVISHIELD to update the Canadian Product Monographs (CPM) for these products to include new safety information about these events.
Please refer to the following website in Health Canada for details:
http://hpr-rps.hres.ca/../summary-safety-review-detail.php?lang=en&linkID=SSR00265
In Hong Kong, the above products are not registered pharmaceutical products. Related news was previously issued by various overseas drug regulatory authorities, and was posted on the Drug Office website since 11 Mar 2021, with the latest update posted on 17 Apr 2021.
Ends/ Tuesday, April 20, 2021
Issued at HKT 15:00
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