Pfizer/BioNTech’s Comirnaty vaccine safety assessment was performed during a phase 3 study with more than 44,000 participants (16 years of age or older), of which more than 21,700 received a vaccine (the others received a placebo) and more than 19,000 were followed up during 2 months after receiving the 2nd dose.
The most frequent adverse reactions were: pain at the site of injection (>80%), fatigue or a feeling of tiredness (>60%), headache (>50%), myalgias and cold cramps (>30%), arthralgias (>20%), fever, and inflammation at the site of injection (>10%); being mostly of mild or moderate intensity and disappearing in a few days after vaccination.
These reactions were more frequent after the second dose and this decreased with age.
Symptomatic treatment can be used, with analgesics and/or antipyretics (such as paracetamol) to treat these effects, although prophylactic use before vaccination is not currently recommended.
Most common adverse reactions
- Are mild or moderate
- Disappear within a few days
- Are more frequent after second dose