Nursing care
Immunization Contraindications, explained for the bedside and the exam
Written and reviewed by Dana Whitfield, RN, MSN · 5 min read · Updated September 2026
Short answer
A true immunization contraindication is a condition that makes serious harm from the vaccine likely, chiefly pregnancy and immunosuppression for live vaccines. A mild illness, a low-grade fever, or a family history of allergy is not a contraindication and should not delay a scheduled vaccine. Precautions, which call for judgement rather than automatic refusal, are a separate category nurses must not confuse with contraindications.
Defining it precisely
A contraindication is a condition in the recipient that creates an unacceptable risk of serious adverse reaction if the vaccine is given. It is not the same as a precaution, which is a condition that might increase risk or reduce vaccine effectiveness but does not rule the vaccine out; a precaution calls for weighing benefit against risk, often deferring rather than refusing outright.
For live-attenuated vaccines, the two contraindications that recur across every formulation are pregnancy and significant immunosuppression. Live vaccines contain a weakened but replicating pathogen, and a compromised or absent immune response can allow that weakened pathogen to cause actual disease. This applies to MMR, varicella, live attenuated influenza, and yellow fever, among others. Inactivated and subunit vaccines carry a much narrower contraindication list because there is no replicating organism to control.
The exceptions that matter
Two beliefs persist among students and, occasionally, at the bedside, and both are wrong. A mild upper respiratory infection, a low-grade fever, or a course of antibiotics for a minor infection is not a reason to withhold a scheduled vaccine. Current guidance treats these as situations where vaccination can proceed, not situations requiring deferral, because withholding vaccines for minor illness only creates missed opportunities without protecting the patient from anything.
A family history of allergic reaction to a vaccine, or a family history of a condition like seizures, is also not a contraindication for that patient. Contraindications are assessed against the individual's own history and current status, not a relative's. What does matter is the patient's own history of a severe allergic reaction, anaphylaxis, to a prior dose or to a vaccine component, which is a genuine contraindication for that specific vaccine going forward.
Using it to prioritise
When triaging whether to give a scheduled vaccine, ask three questions in order. Is the patient pregnant. Is the patient significantly immunosuppressed, whether from disease, chemotherapy, high-dose corticosteroids, or a transplant regimen. Has the patient had a severe allergic reaction to this vaccine or a component of it before. A yes to any of these for a live vaccine, or a yes to the allergy question for any vaccine, means stop and escalate rather than proceed.
If the answer to all three is no, move on to precautions rather than treating the encounter as closed. A precaution, such as a moderate to severe acute illness, or receipt of another live vaccine within the prior four weeks, means clinical judgement is needed, often meaning defer and reschedule, not refuse permanently. Distinguishing contraindication from precaution is the single most useful triage skill in this area.
Traps in exam wording
Exam questions are frequently built around the mild-illness distractor: a scenario describes a patient with a runny nose and a temperature of 37.8°C due for a routine vaccine, and the correct action is to proceed, not to delay. Choosing to withhold in that scenario is the wrong answer even though it feels cautious.
Another common trap presents a family member's allergy or seizure history and expects the test-taker to withhold the vaccine from the patient in front of them. The contraindication must belong to the patient being vaccinated. Watch also for questions that use the word immunosuppressed loosely; mild, short-course topical or low-dose corticosteroid therapy does not meet the threshold that contraindicates live vaccines, while high-dose systemic corticosteroids, active chemotherapy, or a solid organ transplant on immunosuppressive therapy do.
Examples from practice
A pregnant patient at 20 weeks is due for a rubella-containing MMR booster identified through prenatal screening. MMR is withheld throughout pregnancy because it is a live vaccine, and the patient is instead counselled to receive it postpartum, with a recommendation to avoid pregnancy for a defined interval afterward per current guidance.
A patient recently started on high-dose oral corticosteroids for a flare of inflammatory bowel disease is due for a varicella vaccine. Varicella is a live vaccine, and significant immunosuppression from the corticosteroid course is a contraindication, so the vaccine is deferred until the immunosuppressive therapy has been tapered and sufficient time has passed for immune recovery, per institutional and CDC timing guidance.
Summary
A genuine contraindication predicts serious harm and should stop vaccination; a precaution predicts a smaller or theoretical risk and should prompt judgement, often a short deferral rather than an outright refusal. Pregnancy and significant immunosuppression are the contraindications that apply consistently across live vaccines.
Mild illness and family allergy history are not contraindications and should never be documented or acted on as though they were. The patient's own history of severe allergic reaction to a vaccine or its components is the allergy-related fact that actually matters, and it is specific to that patient and that vaccine.
The next step on this is the same as on everything else here: answer questions and read the rationales. Our pharmacology practice questions are the closest set to what this page covers.
One question from the pharmacology set
A client with heart failure is started on furosemide 40 mg PO daily. Which findings should the nurse report to the provider before administering the next dose? Select all that apply.
Rationale
Furosemide is a loop diuretic, so the two things you are watching are potassium and kidney function. A potassium of 2.9 mEq/L is below the 3.5–5.0 reference range and puts the client at risk for dysrhythmia — hold and report. Muscle cramps with palpitations are the clinical face of that same hypokalemia, so they are reported together, not separately. A creatinine that doubles signals the diuresis has outrun renal perfusion. A blood pressure of 132/78 and a 1 kg loss are the expected response to the drug working, not reasons to hold it.
Answer: A, D, E
Common questions
Is a low-grade fever a reason to delay a vaccine?
No. A mild illness with or without a low-grade fever is not a contraindication and vaccination should proceed as scheduled. Only a moderate to severe acute illness is treated as a precaution warranting deferral until the patient recovers.
Can a patient be vaccinated if a sibling had a severe reaction to the same vaccine?
Yes. Contraindications are assessed based on the individual patient's own reaction history, not a family member's. A family history of allergy or adverse reaction does not contraindicate vaccination for the patient in front of you.
Why are live vaccines withheld in pregnancy?
Live vaccines contain a weakened but replicating pathogen, and there is a theoretical risk to the fetus from that replication. Inactivated vaccines, which contain no live organism, generally remain appropriate in pregnancy and are often specifically recommended, such as inactivated influenza vaccine.
What level of immunosuppression counts as a contraindication for live vaccines?
Significant immunosuppression, including active chemotherapy, high-dose systemic corticosteroids sustained over time, and post-transplant immunosuppressive regimens, contraindicates live vaccines. Low-dose or short-course corticosteroid therapy does not typically meet this threshold, and the specific cutoffs should be checked against current CDC or institutional guidance.
What is the difference between a contraindication and a precaution?
A contraindication means the risk of serious harm is high enough that the vaccine should not be given. A precaution means there is an increased risk or a possible reduction in effectiveness, which calls for weighing benefit against risk and often results in deferral rather than outright refusal.
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