Adenovirus Vaccines Shown to Have Hematological Side Effect Concerns

April 13, 2021

As of yesterday, 6.8 million doses of the Johnson & Johnson (Janssen) vaccine have been administered throughout the United States. As of today, the CDC and FDA announced that they are reviewing six reported cases of a “rare & severe type of blood clot in individuals after receiving the vaccine” and are recommending a “pause” in the use of the single-dose Johnson & Johnson COVID-19 vaccine until a more thorough investigation can be conducted. The CDC will convene a meeting of the Advisory Committee on immunization practices (ACIP) tomorrow, Wednesday, April 14th, to further review these cases and assess their potential significance, and this analysis will also be reviewed by the FDA.


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This is not the first time we’re hearing about rare blood clots forming following COVID-19 vaccination, as reports from the Oxford-AstraZeneca vaccine have shown similar concerns. As of this week in Europe, 34 million people have received their first dose of the AstraZeneca vaccine and there are at least 222 suspected cases of dangerous blood clots and low platelet counts. On April 7, the UK Medicines and Healthcare Products Regulatory Agency stated that it had been “investigating at least 79 cases of strokes and clotting events tied to the vaccine, at least 18 of them fatal.”


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The side effects being observed following vaccination are a combination of cerebral venous sinus thrombosis (blood clotting in the sinus that drains blood from the brain) and thrombocytopenia (low levels of blood platelets that stop bleeding). Researchers have concluded that the side effects resemble an autoimmune disorder called heparin-induced thrombocytopenia (HIT) and significantly all six cases occurred among women between the ages of 18 and 48


Some experts initially theorized that vaccine-induced immune thrombotic thrombocytopenia (VITT) was occurring as a result of the antibodies created to fight the virus’ spike protein cross-reacting with Platelet Factor 4 (PF4). PF4 is involved in wound repair and inflammatory responses. If this were the case, it would be a safety concern for all COVID-19 vaccines. However, there is currently no evidence that messenger RNA-based vaccines (such as Pfizer and Moderna), which have been received by tens of millions of people, are causing similar blood clotting and low platelet issues.