The study suggested the interaction between the vaccine and a protein in the blood could be behind the basis of thrombosis in some people.
The team of British and US researchers think this kicks off a chain reaction, involving the immune system, that can results in dangerous clots, the BBC reports.
The very rare but sometimes deadly clots prompted some countries to restrict its use or favour alternative vaccinations.
It prompted an investigation into the handful of rare blood causes and what could be done to prevent it.
AstraZeneca’s own scientists also joined the research project after earlier results from the team were published.
The study is published in the journal Science Advances.
The discovery of rare blood clotting in some people who had received the AstraZeneca caused countries to issue restrictions about who could receive it.
In Australia, the Federal Government gave the green light for people under 40 to access the vaccine upon consultation with their GP.
The most vaccinated countries on Earth
AstraZeneca said the vaccine is thought to have saved more than a million lives around the world and prevented 50 million cases of COVID-19.