The risk of allergic reaction is extremely low. Talk to your doctor if you have a history of allergic reactions or anaphylaxis before getting a COVID-19 vaccine.
There are guidelines in place that may require you to be observed for more than 15 minutes after vaccination in the event of a reaction so that it can be immediately treated.7
Relevant statistics
Pfizer: 21 cases of allergic reaction with 2 million doses delivered (0.001%). In 15 of those 21 cases, the reaction occurred within 15 minutes.8
Moderna: 10 cases of allergic reaction with 4 million doses delivered (0.0003%). In 9 of those 10 cases, the reaction occurred within 15 minutes.9