Part 2 - Vaccine Safety and Adverse Events Following Immunization - Canadian Immunization Guide - Seventh Edition

A contraindication is a condition that significantly increases the chance that a serious adverse event will occur if the vaccine is given. In general, vaccines should not be given when a contraindication exists.

Precautions

A precaution is a condition that may increase the chance of an adverse reaction following immunization or that may compromise the ability of the vaccine to produce immunity. In general, vaccines are deferred when a precaution is present. However, there may be circumstances when the benefits of giving the vaccine outweigh the potential harm, or when reduced vaccine immunogenicity still results in significant benefit to a susceptible, immunocompromised host.

The precautions associated with each vaccine are discussed in detail in the chapters about specific vaccines. See also Table 6 regarding concerns associated with multiple vaccines.

As noted in Table 6, children and adults with neurologic conditions other than GBS are not at increased risk of adverse events after vaccination and may be at greater risk of morbidity and mortality from vaccine-preventable diseases than healthy individuals. Recommended vaccines should not be avoided in children or adults with neurologic conditions. For more information, please refer to the Immunization of Persons with Neurological Disorders chapter.

Table 5. Contraindications and Selected Precautions for Vaccine Administration

Not contraindications

There are a number of conditions or circumstances that some health care providers inappropriately consider to be contraindications to vaccination. This may result in missed opportunities for needed vaccination. Information about some of these conditions is provided in Table 6.

In particular, mild common illnesses (e.g., upper respiratory tract infections, otitis media, colds, diarrhea) or concurrent antibiotic therapy do NOT interfere with the immune response and are NOT a contraindication to vaccination. Almost no acute illness, however severe, interferes significantly with the immune response to vaccine. Some people argue that the occurrence of systemic adverse events may complicate the medical management of the other acute illness or that events associated with the acute illness may mistakenly be thought to be vaccine-related adverse events. These are both theoretical concerns. Almost invariably, this potential risk is much less important than the risk associated with missing an opportunity to give a recommended vaccine.

Conditions	Comments
Concurrent condition in vaccinee
Premature birth	Premature infants respond adequately to vaccines used in infancy are not at significantly increased risk of adverse events. Immunize on schedule, according to child's chronological age. EXCEPTION: Hepatitis B vaccine for infants weighing < 2000 g Mother HBV negative: defer vaccine until infant weighs > 2000 g or is 1 month of age. Mother HBV positive: give infant hepatitis B immune globulin and first dose of hepatitis B vaccine immediately after birth. Will need 4^th dose of HBV (see chapter Immunization of Infants Born Prematurely).
Breast-feeding	After immunization of either a mother or her infant, during breast-feeding there is no reduction in maternal or infant response to vaccines no increase in the risk of adverse events for either mother or breast-feeding infant, following immunization of either.
Pregnancy (inactivated vaccines)	All inactivated vaccines are safe in pregnancy and should be administered if indicated.
Neurologic disorder	No evidence of increased risk of any adverse event following immunization. Such persons may be at increased risk of complications from vaccine-preventable diseases such as influenza and should be immunized appropriately. EXCEPTION: precaution for repeat doses of any vaccine that was temporally associated with an episode of Guillain-Barré syndrome (onset within 8 weeks after immunization).
Cancer (inactivated vaccines)	No increased incidence of adverse reactions to inactivated vaccines No interference between treatment of cancer and inactivated vaccine The immune response may be less than that of healthy adults and children, but any protection following immunization is important because of the increased risk of infection and associated complications
Minor acute illness (with or without fever of ≥ 39.5°C)	No interference with response to vaccine. No increase in risk of adverse event(s) following immunization.
Antibiotic therapy	No effect on response to most inactivated or live vaccines used in Canada. EXCEPTIONS Live oral typhoid vaccine should be delayed until 48 hrs after receipt of the last dose of antibiotics active against Salmonella typhi (penicillins, cephalosporins, trimethoprim-sulfamethoxazole, fluoroquinolones, azithromycin, tetracyclines). Live attenuated varicella vaccine may have reduced effectiveness if given concurrently with antivirals active against herpesviruses. If possible discontinue antivirals active against herpesvirus ≥ 24 hours before immunization and do not re-start until 4 weeks after vaccination.
Convalescence from or exposure to an infection	No interference with response to vaccine. No increase in risk of adverse event(s) following immunization.
Tuberculin skin testing	Any vaccine can be given at the same time as, or at any time after, a tuberculin skin test. Tuberculin skin tests can be given at the same time as, or any time after, any vaccine. However, MMR vaccine may suppress the tuberculin reaction and cause false-negative skin test results if skin tests are administered in the 4-6 weeks after vaccination. The effect of other live virus vaccines such as varicella and yellow fever vaccines on tuberculin reactivity is currently unknown, and no recommendations for postponement of tuberculin skin testing can be made at this time.
Concurrent condition in household contact of vaccinee
Pregnant or immunosuppressed individuals living in household with vaccinee	No risk from any vaccine marketed in Canada to household contacts of vaccinees. Immunization of household contacts of immunosuppressed patients and neonates provides important protection against transmission of disease in the household. Vaccination opportunities in such persons should not be missed.
Concern regarding possible allergy in vaccinee
Gastrointestinal intolerance to eggs	The inability to eat eggs for reasons other than allergy is not associated with an increase of adverse events to any vaccine.
Child, not yet exposed to egg protein	There is no reason to avoid any recommended vaccine. It is very unlikely that such children would have an egg allergy severe enough to cause them to react to the minute quantity of egg protein contained in some vaccines.
History of allergy that does not involve vaccine or component of vaccine	It is safe to immunize people with any of the following: non-specific allergies environmental allergies family histories of allergies administration of allergy shots (desensitization therapy for allergy) allergies to commonly used antibiotics EXCEPTION: vaccines containing neomycin +/or polymyxin (see Table 1, General Considerations chapter) are contraindicated in individuals with IgE-mediated allergies to these antibiotics.
Concern regarding past adverse reaction
History of large local reaction following immunization	A large local reaction to one vaccine is not associated with an increased risk of local reactions to other vaccines. A large local reaction to the fourth dose of DTaP-IPV-Hib does not predict a large reaction to the fifth dose booster (DTaP-IPV), which should be given on schedule. In other circumstances, repeating a dose of a vaccine that previously gave a large local reaction may result in another large local reaction. However, there is no increased risk of systemic adverse events.
Febrile seizures	Childhood vaccines prevent serious diseases that pose a much greater risk to most children's health than seizures that might be associated with a febrile reaction after vaccination.
Family history of adverse reactions to vaccines	Adverse reactions to vaccines are not known to be inherited. EXCEPTION: a family history of an overwhelming infection or fatality after administration of a live vaccine may suggest inheritable severe immunodeficiency, which should be ruled out before administering live vaccines.
Concern regarding capacity to respond to vaccine
Concern about exposure to too many antigens	This concern is not substantiated given the following facts: The vaccines used today are much more highly purified than those in the past, so that even though infants and children now receive more vaccines than they did 30 years ago, the total number of vaccine antigens to which they are exposed is much lower today than it used to be. The human immune system has an enormous capacity to respond to antigens. Infants can respond to about 10,000 different antigens at any one time. Immunization does not add, significantly, to the daily load of foreign antigens even for a 2-month-old baby. The vaccines given at 2, 4 and 6 months of age in Canada engage less than 0.01% of an infant's immune response capacity.
Concern about too many needles	A Canadian study has shown that immunization providers are more concerned about multiple injections than are parents most parents accept multiple injections if it means getting a vaccine with fewer side effects.

Pre-immunization screening for contraindications and precautions

Every patient should be screened for contraindications and precautions before receiving any vaccine dose. Checklists and routine screening questions are useful ways to ensure that this takes place. Effective screening requires only a few questions: sample questions for two circumstances are shown in the box. (Please refer to the Vaccine Administration Practices chapter.)

Selected references

Centers for Disease Control and Prevention. An ounce of prevention... what are the returns? 2^nd edition, 1999. URL: <www.cdc.gov/epo/prevent.htm>.

Halperin BA, Eastwood BJ, Halperin SA. Comparison of parental and health care professional preferences for the acellular or whole cell pertussis vaccine. Pediatric Infectious Disease Journal 1998;17(2):103-9.

Tengs TO, Adams ME, Pliskin JS. Five hundred live-saving interventions and their cost-effectiveness. Risk Analysis 1995;15(3):369-90.

Canadian Immunization Guide 2006

Canadian Immunization Guide
Seventh Edition - 2006