One of the studies also compared the frequency of adverse reactions after the first dose of either the Pfizer or Moderna vaccine in 231 people who had either previously tested positive for SARS-CoV-2, or never been exposed to it. It found that symptoms such as pain or swelling at the injection site were similar in both groups of patients, but whole-body reactions, such as fatigue, headache, chills, fever, and muscle or joint pains, were more frequently reported by those who had recovered from COVID-19.
This fits with data from the ZOE COVID Symptom Study, which encourages participants to log their daily symptoms via a smartphone app, and has more than four million contributors globally. It found that people who have had a previous COVID-19 infection were almost twice as likely to experience one or more mild, whole-body reactions from a dose of the Pfizer-BioNTech vaccine, compared to those who hadn't previously tested positive.