Dr. Laura Sauvé (biography, no disclosures)
What care gaps or frequently asked questions I have noticed
With the success of immunizations, vaccine preventable diseases are now rarely seen; families are increasingly concerned about possible or real adverse events associated with immunizations. Some patients are referred to BC Children’s Hospital’s Family Immunization clinic because the parents are concerned about the risk of, or possibility for an adverse event following immunization. Family physicians may not know who to contact to ask these questions. Parents whose child has had an adverse event are often concerned about future vaccines, and some families are hesitant to get vaccinated in the first place.
Data that answers these questions or gaps
Canada’s vaccine safety system is multifaceted, and starts long before vaccines are put into use. All approved vaccines go through clinical trials where safety is examined closely. Some of the largest safety clinical trials have been done for the rotavirus vaccine, where over 30,000 patients were followed for intussuception. Once Health Canada has approved a vaccine to use in Canada, the National Advisory Committee on Immunization decides whether it will be recommended for use in Canada. The decision to fund vaccines to be included in the routine program then happens at a provincial level, but even vaccines which are not publicly funded have been through the other processes and are considered safe by Health Canada.
Post-licensure studies, or studies after a vaccine is approved for use, are another key aspect of the vaccine safety system. In Canada, vaccine safety is monitored in several ways. Passive surveillance of AEFIs happens at both the provincial and federal level; any immunizing health provider who is aware of an adverse event is expected to notify public health of it, using the “Adverse Event Following Immunization Case Report Form” (see link below). Once reported, a medical health officer reviews the case and determines if individual follow up or recommendations are needed, and makes recommendations about revaccination – sometimes this involves a discussion with or referral to family immunization clinic at BCCH. Adverse event data from BC Centre for Disease Control is then submitted to the “Canadian Adverse Events Following Immunization Surveillance System” (CAEFISS) and epidemiologists at Health Canada analyze and review the reports.
In addition to this passive program, active surveillance has been done at 12 children’s hospitals for the last 25 years via the Canadian Immunization Monitoring Program ACTive (IMPACT) surveillance network; nurse monitors actively look for any child who is admitted to a participating children’s hospital because of a suspected adverse event; they look both for specific adverse events of concern – such as hypotonic hypotensive episodes or seizures after immunization, but also a mixed bag of “other” concerns – anything that the treating physician thought may have been associated with immunization, just in case there is an unexpected adverse event.
In addition there have been many studies worldwide to look at post-marketing vaccine adverse events, using a wide variety of methodologies. The vaccine industry has an obligation to monitor the safety of their products, and both academic vaccinology research groups and different government-funded systems worldwide independently examine vaccine safety.
What are common adverse events following immunization?
Common mild adverse events (that do not require reporting) include local pain and swelling, fever and malaise after most vaccines. Measles-type rashes do occur in 1-10% of children after MMR vaccine. After DTaP vaccines, significant injection site reactions are not uncommon, with up to 6% of children having extensive limb swelling.
Rarely, serious adverse events can occur. Anaphylaxis can occur after approximately 1 in a million doses of vaccine.
Post-vaccination immune thrombocytopenic purpura (ITP) occurs in 1:30,000 – 1:40,000 doses of MMR vaccine (in comparison, it occurs in 1 in ~3000 cases of measles disease). Encephalitis occurs with the administration of measles vaccine in approximately 1 in a million doses, while after measles disease it occurs in 1:1000 cases of measles.
A rare but significant adverse event after rotavirus vaccine is intussusception; surveillance has suggested that the risk is slightly elevated (estimated at 1-7 cases per 100,000 doses of vaccine).
One possible adverse event which causes a lot of worry are neurologic reactions. Hypotonic hyporesponsive episodes are frightening for the parents, but do not have any long term consequences. They are far less common after the acellular pertussis vaccines than the older whole-cell pertussis vaccines.
There has been a great deal of very reassuring data that autism is definitely not linked to any immunization, including large systematic reviews and meta analyses (Pediatric Child Health 2007;12(5):393-5).
What I recommend (practice tip)
Vaccines are safe, but sometimes adverse events following immunizations do happen, and can be very concerning to families. If your patient has an AEFI, there is a voluntary reporting system. Public Health Officers in your local Health Authority will be able to answer most questions or concerns. You can also refer children to BC Children’s Hospital’s Family Immunization Clinic, where a pediatrician with experience in vaccine counselling and adverse events can provide counselling and recommendations about future vaccination. Any patient who has had a moderate-severe adverse event (severe enough to seek medical attention) can be referred and has the chance to be seen by a team with expertise in adverse events, following a standardized protocol. The Family Immunization Clinic also provides vaccines to any BC Children’s Hospital or BC Women’s Hospital patient (or family) who needs immunizations.
References and/or Additional reading
- Family Immunization Clinic at BC Children’s Hospital: http://www.bcchildrens.ca/our-services/clinics/family-immunization
- BC Centers for Disease Control Immunization resources: http://www.bccdc.ca/health-professionals/clinical-resources/communicable-disease-control-manual/immunization
- Immunization Communication Tool for Immunizers: http://www.bccdc.ca/resource-gallery/Documents/Guidelines%20and%20Forms/Guidelines%20and%20Manuals/Immunization/Vaccine%20Safety/BCCDCICT_300315.pdf
- Canadian Immunization guide: https://www.canada.ca/en/public-health/services/canadian-immunization-guide.html
- IMPACT – Immunization Monitoring Program, Active: https://www.cps.ca/en/impact
- CAEFISS – Canadian Adverse Events Following Immunization Surveillance System: https://www.canada.ca/en/public-health/services/immunization/reporting-adverse-events-following-immunization/form.html
- Canadian Pediatric Society Practice Point: Autistic spectrum disorder: No causal relationship with vaccines. Paediatr Child Health 2007;12(5):393-5 https://www.cps.ca/en/documents/position/autistic-spectrum-disorder-no-causal-relationship-with-vaccines
Handouts for Patients
- Your Child’s Best Shot: https://bookstore.cps.ca/stock/details/your-childs-best-shot-a-parents-guide-to-vaccination-4th-edition
- ImmunizeBC website: http://www.immunizebc.ca/
Thank you to Drs Manish Sadarangani and Julie Bettinger for reviewing a draft of this manuscript.