WHO is aware of reports of severe allergic reactions in a small number of people who received a COVID-19 vaccine. A severe allergic reaction - such as anaphylaxis - is a potential but rare side effect with any vaccine. In persons with a known risk, such as previous experience of an allergic reaction to a previous dose of the vaccine or any of the known components in the vaccine, precautions may need to be taken.

WHO recommends that healthcare providers assess patient medical history to determine if a patient is at risk for severe allergic reaction to a COVID-19 vaccine. All immunization providers should be trained to recognize severe allergic reactions and take practical steps to treat such reactions if they occur. 

COVID-19 vaccine use will be closely monitored by national authorities and international bodies, including WHO, to detect serious side effects, including any unexpected side effects. This will help us better understand and manage the specific risks of allergic reactions or other serious side effects to COVID-19 vaccines that may not have been detected during clinical trials, ensuring safe vaccination for all.