Rare adverse events associated with the Johnson & Johnson vaccine typically present within days or weeks following the shot. The risk of having an adverse reaction to the vaccine is very low, and even lower as time passes.
Data show that symptoms of a blood clotting disorder (severe headache or abdominal pain, shortness of breath, neurological symptoms, leg swelling) typically developed about nine days after vaccination, and in no cases did the onset of symptoms occur after 18 days. If you have questions or concerns, consult your doctor.
Updated December 17, 2021