Losses after vaccination of a child are occasionally reported as a side effect at the Lareb Side Effects Center. When lost, there is a brief loss of consciousness. This is usually not serious but can be frightening for parents to watch. There are different forms of disappearances. These are often difficult to distinguish from each other in practice because of the large overlap in symptoms. Below we discuss three types of disappearances.
Pass out
Fainting after vaccination is most common in 4- to 6-year-old children, teenagers and young adults. A stimulus, such as fear, stress or pain, causes the brain to receive too little blood. Fainting usually occurs within an hour of vaccination, especially within 15 minutes. It takes seconds to a few minutes at most. Read more about fainting after vaccination.
Revenge with pallor and lethargy (HHE)
After vaccination, a child may experience sudden weakness, a reduced ability to react and white or blue skin discoloration. This is called a hypotonic-hyporesponsive episode (HHE). This type of relapse is most often seen after the first vaccinations around 2 months. An HHE most often develops after 3 to 4 hours after vaccination. It takes between 6 and 30 minutes. Read more about an HHE after vaccination.
Breath-holding withdrawal (BHS)
The breath holding spell (BHS) is a form of dragging in which the child holds the breath. A BHS arises in a situation where the child is angry, frustrated, afraid or in pain. Children then hold their breath, turn blue and eventually lose consciousness. At that moment, the child can no longer hold its breath and starts breathing again. This causes the blue color to disappear and the child regains consciousness. A breath holding spell lasts less than 1 minute. Read more about a BHS after vaccination.
Lareb wrote a review article on fainting, HHE and BHS after vaccination. Read the entire article in the Journal of Youth Health Care.