It's been tested on 43,500 people, across 6 countries, with no serious side effects being found.
The only side effects are those which are similar to those which some people experience from annual flu vaccinations.
Quote:
"Many vaccines do have side-effects. But the vast majority are not nearly as scary as anti-vaccine activists would have us believe.
"Like all vaccines, this vaccine can cause short-lived side-effects, including pain at the injection site, fever, muscle aches and pains, headache and fatigue," said Dr Penny Ward, a visiting professor in pharmaceutical medicine at King's College London.
Prof Ward pointed out that these kinds of side-effects are also experienced by a high number of people receiving the annual flu vaccination. The side-effects are usually mild, wear off after a couple of days at most, and can be alleviated with paracetamol or ibuprofen".
Source:
https://www.bbc.co.uk/news/54893437