![]() ![]() ![]() ![]() (Efficacy measures how many vaccinated people contract COVID-19 compared with how many infections occur in the placebo or control group. Lower efficacy, in the 60 to 70 per cent range, was found for the AstraZeneca and Janssen products. The Pfizer and Moderna vaccines have the highest efficacy at around 95 per cent. How do the four vaccines compare in efficacy and safety? AstraZeneca and the University of Oxford’s vaccine as well as the first single-dose shot from Janssen, a unit of Johnson & Johnson, were recently authorized by Health Canada, joining the Pfizer-BioNTech and Moderna mRNA vaccines approved in December. There are now four vaccines available to Canadians. There is a need for further studies or improved vaccines that would eliminate these deadly but rare adverse events.Update: As of May 10, the National Advisory Committee on Immunization (NACI) recommends that the AstraZeneca COVID-19 vaccine should not be used in adults under 30 years of age due to a rare but serious side effect of blood clotting.Īs more and more Canadians become eligible for vaccination in what has become a crowded landscape of COVID-19 vaccines, many may wonder what to expect when they roll up their sleeves. There is sufficient evidence to show that COVID-19 vaccination brings along with it, some adverse events that are worthy of note as they can be very life-threatening and fatal. In conclusion, the common takeaway from these studies is that headaches and fevers following COVID-19 vaccination within the first two weeks of vaccination should be taken seriously to rule out VITT. The study concluded that “although the risk of VITT following the COVID-19 vaccine appears to be low, early diagnosis and management can be lifesaving”. Radiological and laboratory investigations revealed a blood clot in the left transverse and superior sagittal sinuses of the brain, and she was diagnosed with VITT. Similarly, in a case report and narrative review by Ali et al., (2023), a case of VITT in a young female who presented with persistent headaches and fevers followed by unequal pupil sizes and right-sided paralysis. Death was the most common outcome in all studies, except for one study in which most of the patients survived. The research found that the cerebral venous sinus of the brain was the most affected site. The platelet count was below the lower limit of the normal range.įurthermore, all patients except one were positive for PF4 antibodies (a test performed to detect antibodies that develop in some people who have been treated with heparin). They reported that, generally, symptoms appeared around the third day for the Pfizer and Moderna vaccines, while for AstraZeneca, symptoms appeared around the ninth day, and headache was the most common symptom. They selected 10 out of 50 articles on the topic from February 1 to May 5, 2021, and performed a descriptive analysis of adverse events caused by the Pfizer, Moderna, and AstraZeneca vaccines. Bilotta et al., (2021), carried out a systematic review and exploratory analysis of articles on Covid-19 vaccine-related thrombosis. When platelets are very low, a person can bleed to death. Platelets stick together when one is injured to form a plug (blood clot) to prevent further bleeding. Platelets are tiny blood cells that are made in the bone marrow from larger cells. On the other hand, Thrombocytopenia is a condition that occurs when the platelet count in the blood becomes too low. The blood clot if not treated can lead to damage to a portion(s) of the brain. Thrombosis occurs when a blood clot forms either in an artery or vein. Research has proven that there are some rare but serious post-vaccination events that need serious attention, such as Vaccine-Induced Thrombocytopenia and Thrombosis (VITT). However, hope came on the horizon with the development and approval of the Pfizer, Moderna, and AstraZeneca vaccines. The cry for a cure or vaccine seemed farfetched. The disease came like a whirlwind and took the world by an unimaginable surprise. The World Health Organization (WHO) declared the novel human coronavirus COVID-19 a global pandemic on the 11th of March 2020. ![]()
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