Denmark, Iceland and Norway have suspended the use of the Oxford-AstraZeneca Covid-19 vaccine while the European Union’s medicines regulator investigates whether the shot could be linked to a number of reports of blood clots.
Please refer to:
- Why I Would Not Take the Russian or Oxford – AstraZeneca Vaccines – Part 2
- (CNN) AstraZeneca pauses coronavirus vaccine trial after unexplained illness in volunteer
- (CNN)NIH ‘very concerned’ about serious side effect in AstraZeneca coronavirus vaccine trial, which offers a plausible mechanism.
An adenovirus vaccine uses an adenovirus vector to transport a transgene cassette, a complete set of instructions for making spike protein, into cells at the injection site.
The manufacturing process of an adenovirus based vaccine uses a live “helper virus” to grow the vector virus, which cannot replicate. The proposed mechanism exploits the inability to completely purify the vaccine product of trace amounts of helper virus. There is more to this, which is explained in (CNN)NIH ‘very concerned’ about serious side effect in AstraZeneca coronavirus vaccine trial.
It is frequently stated that adenoviruses are stable against recombination. This has been found to be false. For this mechanism to generate an actual adverse event would depend upon random recombination, and the particular strain of adenovirus used as a helper.
J&J’s vaccine uses similar technology, adenovirus-as-a-vector, but a different adenovirus strain. This may be why, for unknown reasons of detail, adverse events have not occurred with a frequency that suggests causality.