Non-Severe Events

It is always important to assess the client after administering a vaccine. Health professionals need to recognize the difference between severe events such as anaphylaxis (see next section) and non-severe events that may occur immediately after vaccine administration. Table 4.4 outlines some symptoms that may seem severe and mimic the signs of anaphylaxis but do not pose a life-threatening risk.


Table 4.4: Non-Severe Events

Non-Severe Event Description Management



  • A client who faints suddenly becomes pale, diaphoretic (sweaty), nauseous, and may collapse or experience brief loss of consciousness.
  • Fainting may occur before or after an injection. Fainting is sometimes accompanied by a brief clonic seizure activity (i.e., rhythmic jerking of the limbs).

PREVENT: If you observe early signs of fainting, encourage the client to sit on the floor or lay down to avoid injury from fall in the event of loss of consciousness.


RECOGNIZE: Recovery of consciousness usually occurs within a minute or two, but the person may remain pale, diaphoretic, and mildly hypotensive for several minutes.


RESPOND: Put the client in the recumbent position. Assess the client for injury.


REASSURE: Reassure client and family.






A client experiencing anxiety may appear fearful, pale, and diaphoretic (sweaty). They may also indicate feeling light-headed, dizzy, and numb or tingly in the face and/or extremities. The client may hyperventilate.



PREVENT: If you observe early signs of anxiety, offer the client reassurance and let them know you will not leave them alone.


RECOGNIZE: Symptoms of acute anxiety are stressful for the client but will pass.


RESPOND: Demonstrate calm breathing (diaphragmatic breathing) for the client and encourage them to do the same. It will help the client slow down their breath.






Young children may hold their breath when they are upset and crying hard. The child may appear suddenly silent but visibly agitated. Facial flushing and perioral cyanosis deepen as breath-holding continues.



PREVENT: Use comfort and evidence-informed measures to prevent pain from injection.


RECOGNIZE: Some spells end with resumption of crying, but others end with a brief period of unconsciousness during which breathing resumes.


RESPOND: Encourage parent/caregiver to distract the child if possible. Never scold a child for breath-holding.




Points of Consideration

Health professionals are encouraged to be proactive and report adverse events when they are uncertain whether the event is caused by the vaccine. Expected and mild events that do not require reporting include: fever without any other symptoms, injection site reaction that lasts less than four days, vasovagal syncope (fainting) without injury, or events that are clearly related to other causes.



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Vaccine Practice for Health Professionals: 1st Canadian Edition Copyright © by Oona St-Amant; Jennifer Lapum; Vinita Dubey; Karen Beckermann; Che-Sheu Huang; Carly Weeks; Kate Leslie; and Kim English is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License, except where otherwise noted.

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