TUCSON, Ariz., April 5, 2021 /PRNewswire/ -- More than a dozen countries worldwide temporarily stopped administering the Oxford-AstraZeneca COVID vaccine, notes the Association of American Physicians and Surgeons (AAPS), because of deaths from blood clotting disorders, with either clots or excessive bleeding. Some patients experienced the extremely rare event of clots in the veins that drain blood from the brain (venous sinus thrombosis).
Most countries resumed use after a short pause, when the European Medicines Agency (EMA) said the shot isn't associated with an increase in the overall risk of developing blood clots, and the benefits of using the vaccine continue to outweigh its possible risks:
"The number of reported events exceeds those expected, and causality although not confirmed, cannot therefore be excluded. However, given the rarity of the events, and the difficulty of establishing baseline incidence since COVID-19 itself is resulting in hospitalizations with thromboembolic complications, the strength of any association is uncertain," the Agency stated.
In Germany and other countries use has now been suspended for persons under age 55 or 60.
The U.S. has not yet granted an Emergency Use Authorization (EUA) for the AstraZeneca product. Unlike the Pfizer and Moderna products being rolled out here, it does not use mRNA. Instead, it uses a chimpanzee adenovirus whose DNA has been genetically engineered to code for the spike protein on the surface of the COVID-causing virus. The chimpanzee virus is able to enter human cells and uncoat its DNA but cannot replicate.
All three vaccines cause human cells to manufacture the spike protein, which then induces the immune system to make antibodies to that protein. If the person is then exposed to the virus, the immune system will recognize the threat and mount a defense that should at least minimize symptoms, AAPS explains.
The spike protein is just a fragment of a virus, so it—or the mRNA that codes for it—cannot cause an infection. However, there are questions about whether the spike protein itself can cause harm as it binds to tissue receptors, AAPS points out. Physicians and scientists have asked the EMA about the possibility of blood clots due to the binding of the viral spike protein to platelets. The U.S. Food and Drug Administration (FDA) has not responded to concerns that mRNA products, through spike proteins, have "the potential to cause microvascular injury [inflammation and small blood clots called microthrombi] to the brain, heart, liver and kidneys in ways that were not assessed in the safety trials."
At least 37 people have developed a rare platelet disorder after receiving the Pfizer or Moderna shot; 56-year-old Florida obstetrician Gregory Michael died three days after receiving the Pfizer product.
AAPS states that a cause-and-effect relationship may be impossible to prove, as such diseases occur spontaneously. Health officials note that some 31 million people have received at least one dose, so these events are very rare. They might, however, be just the tip of an iceberg, AAPS warns. According to the Vaccine Adverse Event Reporting System (VAERS), there were 309 cases of thrombocytopenia (low platelets) reported as of Mar 26. AAPS states that people should watch for bruising, rashes, nosebleeds, or bleeding from gums.
There are probably predisposing factors, but AAPS notes there is at present no way to screen for this in advance.
"As with any medical intervention, especially experimental ones, patients need to carefully weigh risks and benefits," stated AAPS executive director Jane M. Orient, M.D. "And be sure to ask about alternatives such as immune support and early treatment.
The Association of American Physicians and Surgeons has represented physicians in all specialties since 1943. Its motto is omnia pro aegroto, everything for the patient.
SOURCE Association of American Physicians and Surgeons (AAPS)