Recently there have been reports of a very rare condition involving blood clots and unusual bleeding after vaccination. Although this condition remains extremely rare there appears to be a higher risk in people shortly after the first dose of the AstraZeneca (AZ) vaccine. Around 4 people develop this condition for every million doses of AZ vaccine doses given. This is seen slightly more often in younger people and tends to occur between 4 days and 2 weeks following vaccination.
Currently, the advice is that it is preferable for people under 30 to have a vaccine other than AZ.
If you have already had a first dose of AZ vaccine without suffering any serious side effects you should complete the course.