Immunization

1. Do not delay immunizations unnecessarily (e.g., vaccinate a child even if he or she has a runny nose).

2. With parents who are hesitant to vaccinate their children, explore the reasons, and counsel them about the risks of deciding against routine immunization of their children.

3. Identify patients who will specifically benefit from immunization (e.g., not just the elderly and children, but also the immunosuppressed, travellers, those with sickle cell anemia, and those at special risk for pneumonia and hepatitis A and B), and ensure it is offered.

4. Clearly document immunizations given to your patients.

5. In patients presenting with a suspected infectious disease, assess immunization status, as the differential diagnosis and consequent treatment in unvaccinated patients is different.

6. In patients presenting with a suspected infectious disease, do not assume that a history of vaccination has provided protection against disease (e.g., pertussis, rubella, diseases acquired while travelling).

Contraindications to vaccination

• Anaphylaxis or other serious reaction (eg. Guillain-Barre syndrome) upon administration of previous dose of a particular vaccine

• Anaphylactic reaction or other serious reaction to a component of a vaccine (eg. egg, gelatin, latex, neomycin, thimerosal)

• Pregnant or immunocompromised/suppressed, active TB should not receive LIVE vaccines (BCG, Zostavax, LAIV, MMRV, rotavirus, Smallpox Typhoid [oral], Yellow fever)

  • Consider delaying inactivated vaccines 1-3 months after immunosuppressive therapy

Contraindications to specific vaccines

• Live attenuated influenza vaccine:

  • Severe asthma

  • Medically attended wheezing in the 7 days prior to vaccination

• Rotavirus vaccine:

  • Uncorrected congenital malformation of GI tract

  • Previous intussusception

• Measles vaccine

  • Neomycin/gelatin allergy

Conditions that are safe to immunize

• Minor acute illness may receive vaccines

  • Exceptions include

    • GI illness for rotavirus (if does not affect dose scheduling age limit), oral cholera, and traveller's diarrhea vaccine

    • Significant nasal congestion that will impede delivery of live-attenuated influenza vaccine

• Adverse events that are not contraindications to vaccination

  • Limb swelling, febrile seizure, hypotonic-hyporesponsive episode, inconsolable crying, oculo-respiratory syndrome (except influenza contraindicated)

When to immunize?

• In infancy

• Before pregnancy

• Before traveling

• When new to the country if not previously immunized

Exploring fears and myths about immunizations

• Side effects – Most common side effects are mild fever and sore extremity. Serious reactions (death, encephalopathy) are so rare that their incidence cannot be calculated.

• Autism – The original paper in the Lancet publishing this association was recently withdrawn and there have been no definitive cases to support this claim. This was originally associated with a preservative agent called thimerosal. The only vaccines in Canada that are given to children and contain thimerosal are the multidose influenza vaccine and Hepatitis B. Both these vaccinations are available in formulations that do not contain thimerosal (ex. Vaxigrip for children and pregnant mothers). The only true contraindication to thimerosal is anaphylaxis.

• Vaccines don’t work – No vaccine is entirely effective. If a vaccine-preventable disease outbreak does occur, some vaccinated individuals will contract the disease. However the proportion of unvaccinated individuals who contract the disease will be much higher than the proportion of vaccinated individuals.

• Vaccine-preventable diseases no longer exist in Canada – Certainly some vaccine-preventable diseases are rarely, if ever, seen in Canada and herd immunity for unvaccinated individuals does occur. However, unvaccinated individuals may still be exposed in their lifetime given the immigrant population that may not have been vaccinated or if the unvaccinated chooses to travel later in life.

Why vaccinate?

• To protect yourself from common (HiB, Influenza, Varicella) or serious (Tetanus, Hepatitis, Meningococcemia) preventable infectious diseases.

• To protect individuals in society who are unable to receive vaccinations (newborns, immunocompromised, elderly)

Special Populations

Premature infants should receive immunizations at the same time (chronological age) as term infants, ie. do not delay vaccinations - in Quebec first vaccines at 2 months old

• Exception: In jurisdictions where Hep B vaccine is given at birth in HbsAg negative mother, delay until infant 2000g or discharged from hospital

Asplenia/Hyposplenia (Sickle cell, thalassemia major)

• Pneumococcal (most common infection in asplenia)

• Meningococcal

• Haemophilus Influenza Type B

• Influenza

• Hep A and B if repeated transfusions

Chronic Liver disease

• Hepatitis A and B

• Influenza

• +/- Pneumococal

Immunization for adults

Pneumococcal 23-valent

• ≥65yo, <65 with specific risk factors

Herpes zoster

• ≥60yo (consider 50-59yo), immunosuppressed

• Live attenuated (Zostavax) vs. Non-live recombinant adjuvanted (Shingrix)

  • 1 dose vs. 2 doses (2 months apart)

  • Herpes Zoster relative risk reduction 51% (NNT 59) vs. 97% (NNT 37)

  • Post-herpetic neuralgia RR reduction 67% (NNT 364) vs. 89%

• Adults ≥50yo who are known VZV seronegative should be given univalent varicella vaccine rather than herpes zoster (routine testing not recommended)

HPV4 or HPV9

• 9-26yo and ≥27yo who are at ongoing risk

  • PIQ recommends vaccinating women 9-45yo, men 9-26yo even if previous HPV exposure

Tetanus/Diphtheria (Td)

• Primary series for unimmunized, and booster every 10y (Note: In Quebec, current guideline is for one single booster after 50yo)

  • Earlier if non-clean/minor wound (if fully vaccinated >5y, if not fully vaccinated needs complete series with Ig)

Rabies

• Pre- or post-exposure if high-risk, consider call local public health for risk assessment

Pertussis

• Once in adulthood (Tdap), as early as possible if close contact with young infants

• One dose during each pregnancy ideally between 26-32 weeks gestation

Influenza

• Annually for all, focus on high risk (6mo-5yo, ≥65yo, chronic disease, pregnancy/postpartum, healthcare worker, frequent contact with above)

  • Not recommended in <6 months old as effectiveness not proven

  • Children <9yo are recommended to get 2 doses one month apart for their first influenza vaccine

Hep A&B

• Risk or anyone who wants protection from hep B

Meningococcal conjugate

• Up to 24yo not immunized, or risk

MMR

• For susceptible adults born in or after 1970 or risk of exposure (traveller, healthcare worker, student, military)

Varicella

• If susceptible or seronegative (2 doses)

Travel vaccines

• Varies by destination