About one in three people recently given a Covid vaccine by the NHS report some side-effects.
None was serious - a common one was some soreness around the injection site, the UK researchers who gathered the feedback found.
Experts say the findings, from about 40,000 people - mostly healthcare workers - are reassuring for the millions having the vaccines now.
The Zoe app team from King's College London found:
- 37% experienced some local "after-effects", such as pain or swelling near the site of the injection, after their first dose, rising to about 45% of the 10,000 who had received two doses
- 14% had at least one whole-body (systemic) after-effect - such as fever, aches or chills - within seven days of the first dose, rising to about 22% after the second dose
These after-effects get better within a few days. All of the medical trials and real-world experiences so far suggest the vaccines are safe and effective.
Source: BBC News, 4 February 2021