Yellow fever vaccine: Canadian Immunization Guide
For health professionals
Last complete chapter revision (see Table of Updates): March 2023
March 2023: This chapter has been reviewed and revised to align with the Statement on the Use of Booster Doses of Yellow Fever Vaccine from the Committee to Advise on Tropical Medicine and Travel (CATMAT).
Revisions to this chapter include:
- The section on epidemiology was updated to expand on affected areas and number of cases.
- International regulations no longer require proof of re-vaccination or a booster dose of yellow fever (YF) vaccine: a single dose confers lifelong immunity for most travellers. A booster dose is recommended for certain individuals. Refer to Booster doses and re-immunization for details.
- The proof of YF vaccination entered on the International certificate of vaccination or prophylaxis should notate the duration of validity as "For the lifetime of the person vaccinated" as suggested by the World Health Organization (WHO).
- YF vaccine is contraindicated in individuals with a past history of thymus disease with abnormal immune function (e.g., thymoma, thymectomy, myasthenia gravis). Previous guidance stated that YF vaccine was "generally not recommended".
On This Page
- Key information
- Preparations authorized for use in Canada
- Immunogenicity, efficacy and effectiveness
- Recommendations for use
- Vaccination of specific populations
- Serologic testing
- Administration practices
- Storage requirements
- Safety and adverse events
- Other considerations
- Chapter revision process
- Selected references
- Yellow Fever (YF) virus is transmitted to humans through the bite of an infected mosquito.
- YF is endemic and intermittently epidemic in sub-Saharan Africa and tropical South America. Risk for acquiring YF is low for travellers, particularly those staying in highly developed major urban areas.
- YF is unique among diseases in that there are International Health Regulations (IHR) which outline the requirements for proof of vaccination when travelling to specific countries. In Canada, YF vaccine is only available at Yellow Fever vaccination centres designated by the Public Health Agency of Canada (PHAC).
- YF vaccine has a seroconversion rate of 95% to 99%; immunity is presumed to be lifelong in healthy individuals.
- The most common adverse events (AE) following YF vaccination are pain, inflammation and swelling at the injection site; weakness, headache, and myalgia.
- YF vaccine is recommended for healthy persons 9 months of age and older.
- YF vaccine may be considered in infants 6 to 8 months of age travelling to countries with risk of YF transmission.
- Persons 60 years of age and older should be considered for primary YF vaccination if travelling to countries with risk of YF transmission. Serious adverse events (SAEs) following vaccination occur more frequently in adults over 60 years of age.
- YF vaccine is recommended for laboratory personnel who work with YF virus.
- Primary immunization is achieved with one dose of YF vaccine.
- The International Certificate of Vaccination or Prophylaxis becomes valid 10 days after primary vaccination.
- While re-vaccination with YF vaccine is not indicated for the majority of immunocompetent travellers, in certain situations booster doses may be required.
- In general, immunocompromised persons, pregnant or lactating persons, and persons with a history of thymus disease should not receive YF vaccine.
- Counselling on routine insect protection and precautions should be provided to all travellers regardless of YF vaccine vaccination status.
- YF immunization (documented by an International certificate of vaccination or prophylaxis) is required to enter certain countries in Africa and South America regardless of the traveller's country of origin. Other countries may require YF vaccination of travellers if the traveller has passed through endemic countries.
- Between 1970 and 2015, 10 cases of YF were reported in unvaccinated travellers from the United States and Europe who visited YF endemic areas of Africa and South America, 8 of whom died. In 1987, there was 1 documented case of yellow fever in a vaccinated traveler; that traveller survived.
- Outbreaks of YF continue to be reported in countries where YF has been identified as a risk.
Yellow fever (YF) is caused by a ribonucleic acid (RNA) virus from the family flaviviridae.
For more information, refer to the Pathogen Safety Data Sheet.
Humans and non-human primates
YF virus is transmitted to humans through the bite of an infected mosquito, primarily Aedes or Haemogogus species. The incubation period is 3 to 6 days. Humans infected with YF virus experience the highest levels of viremia and are infectious to mosquitoes shortly before the onset of fever and for 3 to 5 days afterwards. Because of the high level of viremia in humans, blood borne transmission of YF virus can theoretically occur through transfusion of blood products, intravenous drug use and needle stick injuries. Probable transmission of vaccine strain YF virus from a mother to her infant through breastfeeding has been reported. Vaccine-associated viremia occurs 4 to 10 days after primary YF vaccination and lasts for up to 5 days. Sustained transmission is not possible in Canada because the recognized mosquito vectors are not present.
A traveller's risk for acquiring YF is determined by multiple factors including: immunization status, use of personal protection measures against mosquito bites, location and time of travel, duration of exposure, activities while travelling, and local rate of virus transmission. In endemic areas, the risk for acquiring YF is low for most travellers, particularly those staying in highly developed major urban areas. Greater risk exists for travellers who:
- are unvaccinated
- visit rural, forest or jungle areas
- stay for longer periods of time
- participate in outdoor activities such as recreation or fieldwork
Yellow fever is endemic and intermittently epidemic in sub-Saharan Africa and tropical South America. In West Africa and South America, YF virus transmission is usually associated with the mid-to-late rainy season when the number of mosquitoes generally increases. However, YF virus can be transmitted during the dry season.
Spectrum of clinical illness
Clinical presentation of YF varies in severity from asymptomatic to fatal. When symptomatic, YF is typically characterized by an acute onset of symptoms including fever, chills, headache, backache, prostration (state of weakness), muscle pain, joint pain, nausea, vomiting, photophobia, mild jaundice, and epigastric pain. For others, after a brief remission lasting anywhere between hours to a day, symptoms worsen and the disease advances, eventually leading to renal failure, hemorrhagic symptoms, and thrombocytopenia. Treatment is symptomatic and supportive. The case fatality rate for persons with severe disease is 30%-60%.
The World Health Organization (WHO) estimates that approximately 200,000 YF cases occur annually, with up to 30,000 deaths. YF is endemic and intermittently epidemic in sub-Saharan Africa and tropical South America. In South America, transmission of YF virus occurs mainly in forest areas rather than in urban areas. In Africa, the majority of outbreaks have been reported from West Africa where YF transmission occurs in both rural and densely populated urban areas. The mosquito vectors are present in Asia; however, there have been no documented cases of transmission.
Between 1970 and 2015, 10 cases of YF were reported in unvaccinated travellers from the United States and Europe who visited YF endemic areas of Africa and South America, 8 of whom died. In 1987, there was 1 documented case of yellow fever in a vaccinated traveller.
YF is unique among diseases in that there are International Health Regulations which outline the requirements for proof of vaccination when travelling to specific countries.
Information about countries with risk of yellow fever transmission and countries requiring yellow fever vaccination is available through the World Health Organization. Yellow fever risk maps are also available through the Centers for Disease Control and Prevention.
YF is a nationally and internationally notifiable disease.
Yellow fever outbreaks are reported in the WHO Disease Outbreak News.
Preparations authorized for use in Canada
In Canada, YF vaccine is only available at yellow fever vaccination centres designated by PHAC. For more information, refer to the list of Yellow Fever Vaccination Centres in Canada or call 613-957-8739 or send an email to email@example.com
Yellow fever vaccine
- YF-VAX®: live, attenuated, yellow fever vaccine, Sanofi Pasteur Limited. (YF)
For complete prescribing information, consult the product leaflet or information contained within Health Canada's authorized product monographs available through the Drug Product Database.
Refer to Table 1 in Contents of Immunizing Agents Authorized for Use in Canada in Part 1 for a list of all vaccines authorized for use in Canada and their contents.
Immunogenicity, efficacy and effectiveness
More than 80% of persons immunized with YF vaccine develop neutralizing antibodies 10 days after vaccination and more than 99% by 28 days after vaccination. In immunocompetent individuals, a single dose of yellow fever vaccine likely confers life-long immunity.
Efficacy and effectiveness
Efficacy studies of YF vaccine have not been performed.
YF vaccine appears to provide long-term protection against yellow fever disease. After the administration of more than 540 million doses of YF vaccine, only 23 cases of vaccine failure were reported. Sixteen cases occurred in individuals who received a dose of YF vaccine within the last 10 years, one occurred at 20 years and one at 27 years post-vaccination.
Recommendations for use
Infants up to 8 months of age
Infants less than 6 months of age are at greater risk for YF vaccine-associated neurotropic disease (YEL-AND) following YF vaccination and should not receive YF vaccine.
In general, infants under the age of 9 months should not be vaccinated against YF. However, the Advisory Committee on Immunization Practices (ACIP) in the United States recommends that for infants 6 to 8 months of age travelling to an endemic or transitional area, when travel is unavoidable, the decision to vaccinate needs to balance the risks of YF virus exposure with the risk for AE following immunization (AEFIs). YF vaccination requirements may also differ for infants in certain countries. Although the risk of serious adverse neurologic events is less than that of infants less than six months of age, it is still higher than that of infants 9 months and older.
Healthy individuals (9 months of age and older)
One dose of YF vaccine is recommended for immunocompetent individuals who are 9 months of age and older and who travel to countries with risk of YF transmission.
At 9 months of age, the risk of SAEs becomes much lower and antibody response increases, thus improving the safety and efficacy profiles of the YF vaccine.
Given the more frequent occurrence of SAEs in older adults, immunocompetent individuals 60 years of age and older should be considered for primary YF vaccination only if travel to countries with risk of YF transmission cannot be avoided and a high level of protection against mosquito exposure is not feasible. YF vaccine is also recommended for laboratory personnel who work with YF virus.
For more information, refer to Travellers.
Booster doses and re-immunization
Booster doses of YF vaccine are not recommended for most immunocompetent travellers. The Committee to Advise on Tropical Medicine and Travel (CATMAT) recommends that, based on a case-by-case assessment of benefit versus risk, the use of a one-time booster dose is recommended for:
- Individuals in whom response to prior vaccination may have been diminished (e.g., who were pregnant or taking immunosuppressive medication, or had an immunocompromising illness at the time of vaccination, and those who underwent a hematopoietic stem cell transplant since their last YF vaccine dose).
- Individuals who received a previous dose which may have been inadequate for long term protection (e.g., fractional dose, undocumented or improperly documented dose or a dose administered by a non-accredited provider).
- Individuals at particularly high risk of exposure (e.g., travelling to an area experiencing an epidemic or major outbreak, or travelling frequently or for prolonged periods to countries with risk of YF transmission): the booster should be considered if at least 10 years have elapsed since primary vaccination and no previous booster doses were administered.
Re-immunization every 10 years is recommended for:
- laboratory personnel working with YF virus unless measured neutralizing antibody titre to yellow fever virus confirms ongoing protection
- HIV-positive individuals who are travelling to countries with risk of YF transmission
There is very little information on longer-term immune response in those vaccinated in early childhood; research is ongoing to determine the duration of immunity in infants and young children after a single dose of vaccine. At this point, CATMAT does not make specific recommendations for a booster dose of the YF vaccine in young children. Individual assessment of risks and benefits should be done if considering re-immunization of children who received a single dose of vaccine prior to 1 year of age. Serology may be considered in this case where the immune response to prior YF vaccination may be diminished, if travelling to an area with risk of transmission.
In 2014, the WHO stated that a single dose of yellow fever vaccine confers life-long immunity and revised the International Health Regulations. As of July 2016, revaccination or a booster dose of yellow fever vaccine is not required of international travellers as a condition of entry into a country.
Vaccination of specific populations
Pregnancy and breastfeeding
In general, YF vaccine, like other live viral vaccines, should be avoided in pregnancy. Pregnant or breastfeeding individuals should be considered for YF immunization only if they are travelling to countries with risk of YF transmission, travel cannot be postponed, and a high level of protection against mosquito exposure is not feasible.
While the effects of YF vaccine in pregnancy are not well documented, many pregnant individuals have received the vaccine without significant AE There have been numerous studies of individuals who were exposed to YF vaccine during pregnancy, using both active and passive surveillance methods for the ascertainment of AE involving the fetus; in these, no worrisome safety signals were detected. One study documented an increased rate of minor skin malformations (such as small nevi) in offspring of vaccinated mothers as compared to the reference population, thought to be due to evaluation bias. Inadvertent immunization of pregnant individuals is not an indication for termination of pregnancy.
Seroconversion rates are lower in pregnant individuals who are immunized, especially in the third trimester. Antibody titres may be considered post-immunization to ensure appropriate immune response in individuals who remain at risk for YF. Refer to Serologic testing for additional information. If serology is not available and an individual is travelling to a country with risk of YF transmission after completion of a pregnancy, revaccination prior to travel should be considered.
If pregnant individuals must travel to a country that requires documentation, but where there is no risk of YF transmission, a waiver or Certificate of Medical Contraindication to Vaccination should be provided.
In general, breastfeeding individuals should not be vaccinated, particularly when infants are under 9 months of age. There have been 3 reported cases of probable transmission of vaccine strain of YF virus from a mother to her infant through breastfeeding, resulting in encephalitis in the infants. If, for entry to a country, a yellow fever vaccination certificate is required and there is no risk of acquiring yellow fever in the region to be visited, a waiver of vaccination should be sought. If travel to a highly endemic area cannot be postponed, the mother should be given information on the rare risk of vaccination causing disease in the infant, which should be weighed against the risk of yellow fever infection in the mother and infant.
For additional information, refer to Immunization of Travellers in Part 3 and Travellers.
In general, immunocompromised persons should not receive YF vaccine because of the risk of disease caused by the vaccine strain. When considering immunization of an immunocompromised person, approval from the individual's attending physician should be obtained before vaccination. For complex cases, referral to a physician with expertise in immunization and/or immunodeficiency is advised.
For the immunocompromised traveller, the potential risks associated with administering the YF vaccine should be weighed against the potential benefits. Where there is a country-specific vaccine requirement but the risks associated with vaccine administration outweigh the medical benefits, a Certificate of Medical Contraindication to Vaccination should be provided. Travellers thought to have a mild degree of immune suppression who will be at significant risk for acquiring YF (e.g., travel to an area of endemic or transitional transmission risk), should be offered YF vaccine and advised of the theoretical risks. Profoundly immune suppressed travellers, who in spite of being informed of the risks, plan a trip to an area of active YF risk, should obtain advice from a travel medicine expert and should rigorously adhere to mosquito protection measures.
Refer to Immunization of Immunocompromised Persons in Part 3 for additional information. Refer to Booster doses and re-immunization, Serologic testing, and Contraindications and precautions for additional information.
Persons with chronic diseases
Refer to Contraindications and precautions and Immunization of Persons with Chronic Diseases in Part 3 for information regarding specific chronic diseases.
The decision to immunize a traveller against YF should take into account the traveller's itinerary and the associated risk for exposure to YF virus, the requirements of the country to be visited (including stopovers and airport transit), individual risk factors (e.g., age, immune status), and the potential for SAEs following vaccination.
There are countries where yellow fever transmission occurs that do not have requirements for vaccination for entry and therefore unvaccinated travellers may be at greater risk, especially if visiting a yellow fever risk area.
YF vaccine is recommended for immunocompetent travellers (9 months and older) passing through, visiting or living in countries with risk of YF transmission or when YF immunization is required to enter the country. Refer to the list of countries with risk of YF transmission and countries requiring YF vaccination available through WHO. Some countries may also require YF immunization if transiting through a country/region at risk of YF transmission
YF vaccine is recommended for those travelling to countries in which there is increased risk of exposure to mosquitoes because of prolonged stay, heavy exposure to mosquitoes, or inability to avoid mosquito bites.
YF vaccination is generally not recommended for travellers visiting countries with low potential for YF virus exposure, including those whose itineraries are restricted to areas with no risk. For additional information, refer to Travellers planning for stopovers and airport transit.
International certificates of vaccination or prophylaxis (ICVP)
Under the WHO's International Health Regulations, YF immunization (documented by ICVP) is required to enter certain countries in Africa and South America regardless of the traveller's country of origin.
Other countries require YF vaccination of travellers if the traveller has passed through endemic countries.
In some Asian and tropical countries where YF disease does not exist but the transmitting mosquito is present, immunization is required for travellers arriving from an endemic country to prevent importation of the disease.
Some countries do not require YF vaccination of infants younger than a certain age (e.g., less than 1 year).For immunized individuals, the ICVP is valid for the person's lifetime, beginning 10 days after primary immunization and immediately after re-immunization. Travellers requiring the certificate but in whom the YF vaccine is medically contraindicated (refer to Contraindications and precautions) can be provided with an International Certificate of Medical Contraindication to Vaccination by the yellow fever vaccination centre following an individual risk assessment. Travellers without a valid ICVP or a Certificate of Medical Contraindication to Vaccination may be denied entry into a country requiring such documentation, quarantined, or offered immunization at the point of entry (e.g., at the airport), potentially putting the health of the traveller at risk.
The ICVP is issued only to individuals who receive a full dose of the YF vaccine. For more information, refer to CATMAT's Interim Canadian recommendations for the use of fractional dose of yellow fever vaccine during a vaccine shortage.
Travellers planning for stopovers and airport transit
Transit times of 12 hours or less in an international airport poses very low risk for YF virus transmission irrespective of the YF risk classification of the country in which the airport is located. Such a transit typically does not warrant vaccination, since immunization is not medically indicated.
However, defining specific entry requirements is under the control of each individual country. Some countries will not allow entry without proper documentation of vaccination or certificate of medical contraindication. Travellers without proper documentation may be denied entry or subjected to vaccination at the airport.
This should be considered during review of itineraries and pre-travel counselling. In cases when vaccination is not medically indicated but there is concern that lack of documentation may jeopardize travel, providing a medical certificate of contraindication may be considered. Unfortunately, some countries may deny entry despite proper documentation of medical contraindication to vaccination.
Vaccine providers should check the Government of Canada, CDC or WHO website for an updated list of countries considered endemic or transitional for YF and/or requiring YF vaccination for entry.
Destination-specific recommendations for immunization against YF are available on the Government of Canada Travel Health and Safety website.
Laboratory personnel who work with YF virus and those working in endemic YF areas should receive YF vaccine. For additional information, refer to Booster doses and re-immunization, Serologic testing and Immunization of Workers in Part 3.
Serologic testing is generally not recommended for immunocompetent individuals. However, serologic testing may still be useful in cases where there is concern about the ability of an individual to generate a sustained immune response to the YF vaccine. An antibody titre (plaque reduction neutralization test) of greater than 1:20 indicates serological response.
Due to the low level of evidence on the long-term protection of the YF vaccine, an antibody titre (plaque reduction neutralisation test) may be considered if more than 10 years have lapsed since the most recent vaccination for immunocompetent individuals with a particularly high risk of exposure including:
- laboratory personnel working with YF virus
- travellers and workers with regular and ongoing risk of exposure to YF endemic areas
An antibody titre may also be considered post-vaccination for individuals whose response to prior YF vaccination may have been diminished, at time of immunization, including those who were:
- taking immunosuppressive medication
- affected by an immunocompromising illness
Alternatively, as there may often be challenges or delays in acquiring serology, and given that severe AE from re-immunization are very rare, a booster dose may be administered to these specific groups to ensure protection before subsequent travel to areas with risk of YF transmission. For additional information, refer to Booster doses and re-immunization.
Given the uncertainty in longer-term immune response in those vaccinated in early childhood, serology may also be considered for travellers who received a single dose of YF vaccine prior to 1 year of age.
Dose, route of administration, and schedule
Each dose is 0.5 mL.
Route of administration
YF vaccine should be administered subcutaneously.
Refer to Vaccine Administration Practices in Part 1 for additional information.
One dose of YF vaccine should be administered. Persons who receive YF vaccines in countries other than the United States and Canada and who have proof of vaccination should be considered protected against YF.
In the event of a shortage, some travellers going to yellow fever endemic or epidemic regions may not have access to a full dose of yellow fever vaccine, and as such, these travellers face the choice of not receiving a vaccine or receiving a fractional dose of vaccine. However, according to the WHO, a fractional dose of the yellow fever vaccine would not qualify for the ICVP under the International Health Regulations.
The ICVP is issued only to individuals who receive a full dose of the YF vaccine. For more information, refer to CATMAT's Interim Canadian recommendations for the use of fractional dose of yellow fever vaccine during a vaccine shortage.
Concurrent administration with other vaccines
YF vaccine may be administered concomitantly with the following vaccines: measles, mumps, rubella, polio, diphtheria, tetanus, pertussis, hepatitis B, hepatitis A, oral cholera, and oral or parenteral typhoid.
Different injection sites and separate needles and syringes must be used for concomitant parenteral injections.
If not given concurrently, a minimal interval of 4 weeks is recommended between administration of YF vaccine and other live parenteral vaccines.
Oral typhoid or oral cholera vaccine can be administered at any interval before or after YF vaccine.
There are no data available regarding possible interference between YF vaccine and rabies, human papillomavirus, Japanese encephalitis, live attenuated influenza, or varicella vaccines.
Refer to Timing of Vaccine Administration in Part 1 for additional general information.
Store YF vaccine in a refrigerator at +2°C to +8°C. Do not freeze. Refrigerate the reconstituted vaccine and use within 1 hour following reconstitution. Refer to Storage and Handling of Immunizing Agents in Part 1 for additional general information.
Safety and adverse events
Refer to Adverse Events Following Immunization in Part 2 for additional general information on vaccine safety.
In the last few years, a number of rare, but serious reactions to YF vaccination have
been documented, mostly following the first dose. However, YF vaccines are generally well tolerated. Based on years of observational data, severe adverse reactions to booster doses of YF vaccine are very rare.
Reactions to the vaccine are usually mild and transient in nature. Mild AE such as headaches, myalgia, and low-grade fever may last for 5 to 10 days after vaccination. Less than 0.2% of recipients had to limit daily activities due to an adverse event following vaccination.
Reporting rates of SAEs increase with increasing age.
Common and very common adverse events
Common AE occur in 1% to less than 10% of vaccinees. Very common AE occur in 10% or more of vaccinees.
In clinical trials, the most common AE were injection site reactions such as localized edema and a mass or pain at the injection site. Other very common AE following immunization included headache and myalgia.
Common AE included nausea and rash.
Uncommon, rare and very rare adverse events
Uncommon AE occur in 0.1% to less than 1% of vaccinees. Rare and very rare AE occur, respectively, in 0.01% to less than 0.1% of vaccinees.
Anaphylaxis was reported in 1.3 per 100,000 vaccine doses distributed based on reporting rates to the United States Vaccine Adverse Event Reporting System (VAERS) from 2007-2013. This rate includes reports where another vaccine was co-administered with YF vaccine. For anaphylactic reactions where the dose number was known, all occurred after primary vaccination.
YF vaccine-associated neurotropic disease (YEL-AND)
YEL-AND is a group of clinical syndromes that includes meningoencephalitis (neurotropic disease), acute disseminated encephalomyelitis, Guillain Barré syndrome, and acute bulbar palsy.
Neurotropic disease occurs as a result of YF vaccine virus invasion of the central nervous system (CNS). The other syndromes are autoimmune manifestations in which antibodies and/or T-cells produced in response to the vaccine cross-react with neuronal epitopes leading to CNS or peripheral nerve damage. The clinical course is typically brief with generally complete recovery. Fatality is rare.
YEL-AND can present in any age group, within 30 days following immunization and is seen almost exclusively in primary vaccine recipients. Children less than nine months of age and older persons are at greater risk for YEL-AND.
YEL-AND was reported in 0.8 per 100,000 vaccine doses distributed, largely following primary vaccination, based on reporting rates to the United States VAERS from 2007-2013. The reporting rate was triple for those 60 to 69 years of age (2.5 per 100,000 doses) and double for those over 70 years of age (1.6 per 100,000 doses). These rates include reports where another vaccine was co-administered with YF vaccine. When infants and elderly are not given the vaccine, recent surveillance data suggest population-based incidence rates drop close to zero.
YF vaccine-associated viscerotropic disease (YEL-AVD)
YEL-AVD is characterized by severe illness and multi-organ failure. It resembles wild-type YF infection with onset is within 10 days of vaccination.
YEL-AVD was reported in 0.3 per 100,000 vaccine doses distributed, largely following primary vaccination, based on reporting rates to the United States VAERS from 2007-2013. This rate includes reports where another vaccine was co-administered with YF vaccine.
The risk of YEL-AVD increases with age. Incidence is estimated to be 1.0-1.1 per 100,000 for those 60-69 years of age; 2.3-3.2 per 100,000 for those over 70 years of age. The case fatality rate is 65% overall and is higher in women than men (90% versus 50%).
YEL-AVD is seen almost exclusively in primary vaccine recipients. Extensive investigations of cases suggest that YEL-AVD is linked to various host factors including older age, and thymus disease (thymoma, myasthenia gravis, thymectomy), and is not associated with a change in virulence of the vaccine virus.
Other safety issues
Based on 3 case reports, YF virus may be transmitted from a lactating mother to her infant. Further research is required to establish the risk of infant exposure through breastfeeding as the frequency is unknown.
For more information, refer to Pregnancy and breastfeeding.
Guidance on reporting Adverse Events Following Immunization (AEFI)
To ensure the ongoing safety of vaccines in Canada, reporting of AEFIs by vaccine providers and other clinicians is critical, and in some jurisdictions, reporting is mandatory under the law.
Vaccine providers are asked to report AEFIs through local public health officials and to check for specific AEFI reporting requirements in their province or territory. In general, any serious or unexpected adverse event felt to be temporally related to vaccination should be reported.
Vaccine providers are asked to report the following AEFIs in particular:
- YF vaccine-associated neurotropic disease (YEL-AND)
- YF vaccine-associated viscerotropic disease (YEL-AVD)
- Any serious or unexpected adverse event felt to be temporally related to vaccination
For additional information about AEFI reporting, please refer to Reporting Adverse Events Following Immunization (AEFI) in Canada. For general vaccine safety information, refer to Adverse Events Following Immunization in Part 2.
Contraindications and precautions
There is an association between YF vaccine-associated viscerotropic disease (YEL-AVD) and a history of thymus disease. Therefore, YF vaccine is contraindicated for persons with a history of thymus disease with abnormal immune function (e.g., thymoma, thymectomy, myasthenia gravis).
YF vaccine is contraindicated in persons with history of anaphylaxis after previous administration of the vaccine and in persons with proven immediate or anaphylactic hypersensitivity to any component of the vaccine or its container. Individuals requiring YF immunization who have suspected hypersensitivity or non-anaphylactic allergy to vaccine components, including chicken or egg proteins and gelatin, should be referred to an allergist for evaluation.
Refer to Table 1 in Contents of Immunizing Agents Authorized for Use in Canada in Part 1 for a list of vaccines authorized for use in Canada and their contents.
Infants less than 6 months of age should not receive YF vaccine because of the risk of YEL-AND.
Administration of YF vaccine should be postponed in persons with moderate or severe acute illness. Persons with minor acute illness (with or without fever) may be vaccinated.
For use of YF vaccine in immunocompromised persons, refer to the Immunization of Immunocompromised Persons in Part 3.
For more information, refer to Contraindications and Precautions in Part 2.
The effect of YF vaccine on tuberculin reactivity is unknown. Until data are available, if tuberculin skin testing or an Interferon Gamma Release Assay (IGRA) is required, it should be done on the same day as immunization or delayed for at least 4 weeks after YF vaccination.
Vaccination with YF vaccine may take place at any time after tuberculin skin testing has been performed and/or read.
Chapter revision process
This chapter update was conducted in collaboration with the Committee to Advise on Tropical Medicine and Travel (CATMAT). Recommendations are based on CATMAT's Statement on the Use of Booster Doses of Yellow Fever Vaccine.
PHAC would like to acknowledge the contributions of the CATMAT Yellow Fever Working Group, and PHAC participants C Jensen, N Mohamed, O Baclic, and E Abrams.
- Committee to Advise on Tropical Medicine and Travel. Statement on the Use of Booster Doses of Yellow Fever Vaccine. Ottawa: Public Health Agency of Canada; 2018. Retrieved from: https://www.canada.ca/en/public-health/services/publications/diseases-conditions/use-booster-doses-yellow-fever-vaccine.html
- Committee to Advise on Tropical Medicine and Travel. Statement for travellers and yellow fever. Can Comm Dis Rep. 2013;39(2):1.
- Disease News Outbreak - Yellow fever - Brazil [Internet]. Geneva: World Health Organization; 2018 [updated 2018-03-09; cited 2018-03-09]. Available from: http://www.who.int/csr/don/09-march-2018-yellow-fever-brazil/en/
- International and travel health [Internet]. Geneva: World Health Organization; 2017 [updated 31-01-2017; cited 2018-03-02]. Available from: http://www.who.int/ith/en/
- Kimberlin DW, Long SS, Brady MT. Red Book 2015: Report of the Committee on Infectious Diseases. 30th ed. Elk Grove Village, Chicago: American Academy of Pediatrics; 2015.
- Lindsey NP, Rabe IB, Miller ER, Fischer M, Staples JE. Adverse event reports following yellow fever vaccination, 2007-13. J Travel Med. 2016;23(5). https://doi.org/10.1093/jtm/taw045
- MMWR - Yellow fever vaccine recommendations of ACIP, 2010 https://www.cdc.gov/mmwr/pdf/rr/rr5907.pdf
- MMWR - Yellow fever vaccine recommendations of ACIP, 2015 https://www.cdc.gov/mmwr/preview/mmwrhtml/mm6423a5.htm
- New yellow fever vaccination requirements for travellers [Internet]. Geneva: World Health Organization; 2016 [updated 2016-07-27; cited 2018-03-02]. Available from: http://www.who.int/ith/updates/20160727/en
- Plotkin SA, Orenstein WA, Offit PA. Vaccines. Seventh ed. Philadelphia, PA: Elsevier; 2018.
- Procedures for Yellow Fever Vaccination Centres in Canada. [Internet]. Ottawa: Public Health Agency of Canada; 2015 [cited 2017-02-03]. Available from: https://www.canada.ca/en/public-health/services/travel-health/yellow-fever/procedures/procedures-yellow-fever-centres.html
- Sanofi Pasteur Limited. Product Monograph - YF-VAX®. April 2019.
- Trollfors B. Red Book: 2009 Report of the Committee on Infectious Disease. Acta Pædiatrica. 2010;99(3):479-.
- Yellow fever among travellers returning from South America. [Internet]. Stockholm: European Centre for Disease Prevention and Control.; 2017 [cited 2018-03-03]. Available from: https://ecdc.europa.eu/en/publications-data/yellow-fever-among-travellers-returning-south-america-march-2017
- Yellow fever vaccination booster [Internet]. Geneva: World Health Organization; 2014 [updated 2014-10-24; cited 2018-03-02]. Available from: http://www.who.int/ith/updates/20140605/en
- Yellow Fever Working Group on behalf of the Committee to Advise on Tropical Medicine and Travel (CATMAT). Interim Canadian recommendations for the use of a fractional dose of yellow fever vaccine during a vaccine shortage. Can Comm Dis Rep 2016;42:158-60.
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