Nevertheless, German researchers say that blood clots occur more frequently in recipients of the AstraZeneca-Oxford vaccine than would be expected in people who have never had the chance.
What symptoms should doctors and recipients of vaccines look for if an adverse reaction such as blood clots occurs?
European regulators have recommended that recipients of the vaccine seek medical help for a number of possible symptoms, including swelling in the leg, persistent abdominal pain, severe and persistent headache or dull face, and small blood spots under the skin outside the area where the injection took place . was given.
But the set of symptoms was so vague that the British emergency rooms had an increase in patients worrying that it would fit the description. As a result, some emergency physicians have asked for more central guidance on how to treat what they describe as largely unnecessary hospital visits.
German researchers have described specialized blood tests that can be used to diagnose the disorder, and they have suggested that they be treated with a blood product called intravenous immunoglobulin, which is used to treat various immune disorders.
Drugs called anticoagulants, or blood thinners, can also be administered, but not a common use – heparin – because the vaccine-related condition is very similar to that rarely found in people who get heparin.
Do vaccines cause other bleeding disorders?
Other vaccines, especially those given to children for measles, mumps and rubella, have been linked to the temporarily reduced levels of platelets, a blood component that is essential for clotting.
Decreased platelet levels have been reported in small numbers of patients receiving the Moderna, Pfizer-BioNTech and AstraZeneca vaccines. One recipient, a Florida doctor, died of a brain hemorrhage when his platelet level could not recover, and another was admitted to the hospital. U.S. health officials said the cases are being investigated, but they have not reported the findings of the reviews and have not yet indicated that there is any connection to the vaccines.