The most common symptoms they reported were fatigue (9%), headache
(8%) and chills or shivers (4%), mostly during the first two days
after receiving the vaccine. However, approximately a third of those
who had previously had COVID-19 reported at least one mild, whole-body
reaction within seven days, compared to 19% of those who hadn’t
previously had COVID-19.
People aged under 55 were more likely to experience such symptoms, and
they were also more common when people received their second dose of
vaccine. In most cases, these mild side effects were short-lived, with
just 3% of people experiencing them beyond three days.