Wasps inject venom as they sting you, sometimes the stinger may be left in the skin. The venom is poisonous and may cause direct injury to the human body. This injury is usually confined to the areas close to the sting or stings.

Symptoms of an allergic reaction is as follows:

Hives (raised itchy bumps on the skin) and itching all over the body

Swelling of the mouth or throat or both

Wheezing, Shortness of breath or other difficulty breathing
Nausea, Vomiting, Anxiety, Chest pain, and Low blood pressure (weakness or fainting).

Consider taking an antihistamine such as Benadryl if you feel you are allergic and if it is a serious case seek medical attention. 

If it has been more than 10 years since your last tetanus booster, get a booster within the next few days.