A vacuum cleaner doesn't need a HEPA filter because it's an optional attachment. However, for individuals who suffer from allergies or asthma, using a vacuum cleaner with a HEPA filter may provide significant relief from symptoms.
HEPA stands for "high energy particulate air," which is a filtration system that can trap large amounts of very fine particles that would otherwise be ejected back into the room through the vacuum's exhaust. Many of these small particles, such as pollen, trigger allergy and asthma symptoms. Using a vacuum cleaner with a HEPA filter, especially a HEPA filter designated as a true HEPA filter, maintains clean air in the home, which may reduce symptoms.