Questions and Answers on Pandemic (H1N1) 2009 Influenza: The Vaccine
Additional Reading and Useful Links
Appreciation
What problems have developed in young children receiving the second shot of the adjuvant Pandemic (H1N1) 2009 vaccine? (Added December 21, 2009)
Reports from Europe show that young children (under 4 years of age) who received a second dose of an adjuvant H1N1 2009 vaccine are more likely to develop a fever. In Canada, health care professionals should continue to administer the second dose in these young children as it will enhance the immune response. Parents should be informed that fever may occur following the second dose and monitor the temperature of children following vaccination. If necessary, they may take measures to lower the fever such as giving acetaminophen if it occurs.
[Back to Top]
Should we still encourage Pandemic (H1N1) 2009 immunization if the 2nd wave is over? (Added December 11, 2009)
Some physicians have asked if we need to encourage mass immunization now that the second wave of H1N1 2009 appears to be on the wane. The answer is a definite “yes”. We know from past pandemics that major outbreaks can occur in a 3rd or even 4th wave that are almost as serious as the initial one. High immunization rates in children and youth can decrease the probability of a third wave occurring. Not only will immunization in this age group benefit them but it will also benefit the community since children and youth are the major spreaders of influenza within a community. Immunizing them will decrease the risk of infection for those who cannot be immunized (e.g. under 6 months of age) and those who cannot respond well to vaccine (e.g. those on chemotherapy). All children and youth should be encouraged to be immunized for their own protection and for the added protection of the community.
[Back to Top]
Should all children be given the seasonal influenza and the Pandemic (H1N1) 2009 vaccines?
Influenza vaccination has proven benefits; it protects the person vaccinated and the people around them. The Canadian Paediatric Society recommends that all children over the age of 6 months receive the annual seasonal flu vaccine. It is especially important that children ages 6-23 months as well as older children with chronic medical conditions get the seasonal influenza vaccine. This year, all children should also receive the vaccine against the H1N1 2009 virus. Anyone living with or caring for children, particularly infants under age 2, should receive both the seasonal and the H1N1 2009 vaccines this year.
Children under 6 months of age are unlikely to have an adequate immune response to the vaccine but are likely to benefit from immunization of household members or through prenatal immunization of their mothers.
[Back to Top]
For what age groups are two doses of H1N1 influenza vaccine recommended?
The Public Health Agency of Canada recommendations as of November 12, 2009 include three components:
- Children between 6 months of age and under 3 years of age should receive two half-doses of adjuvanted H1N1 2009 flu vaccine, administered at least 21 days apart.
- Children with significant chronic health conditions who are over 3 years of age and under 10 years of age should receive their first half-dose of the H1N1 2009 flu vaccine as soon as possible. These children should receive a second half-dose of the H1N1 2009 flu vaccine once immunization of other priority groups has been completed.
- Healthy children over 3 years of age should only need a single dose of the H1N1 2009 vaccine and do not need to return for a second vaccine for now. This recommendation may be updated as more information becomes available.
Please note that provinces and territories may choose to follow different dosing schedules. Please refer to your provincial, territorial, or regional public health department for any local changes to these recommendations.
Through IMPACT, the CPS and Public Health Agency of Canada are doing active surveillance of children and youth hospitalized due to H1N1 2009 influenza. This information will be used to closely monitor the situation in Canada, and with review of data from other countries, will be used to update, if needed, the H1N1 2009 vaccine dosing guidelines for children under 10 years of age.
[Back to Top]
Should the seasonal influenza vaccine be given as well as the Pandemic (H1N1) 2009 vaccine?
Provincial or territorial public health programs make the decisions on which vaccine will be available and when. Check with your local public health authority. Confusion about the order in giving the vaccines is due to an unpublished Canadian study suggesting that in the first H1N1 2009 wave there may have been an increased risk of acquiring H1N1 2009 in people who had received the seasonal influenza vaccine last winter. This observation may or may not be accurate. So far, experts in the United States, Australia and the United Kingdom have examined the data from their populations and have not seen an increased risk of H1N1 2009 infection after receiving the seasonal influenza vaccine. Until this issue has been sorted out, some provinces have chosen to delay seasonal influenza vaccine until after H1N1 2009 vaccine has been given while others are giving both vaccines concurrently.
[Back to Top]
What if a child had Pandemic (H1N1) 2009 infection last spring or this fall? Should he/she still get the Pandemic (H1N1) 2009 vaccine?
If the child’s influenza-like illness was not proven to be H1N1 2009 infection (RT-PCR or culture identification), vaccinate the child.
If the child had proven infection last spring (RT-PCR or culture identification)
- High-risk immunocompromised - vaccinate the child
- High-risk chronic disease - consider vaccinating the child
- Low risk healthy - no vaccination, but vaccine is not contraindicated
What is the best way to minimize the pain a child may have getting the flu shot?
Flu vaccine injections are less painful if given quickly and without aspiration. Authorities involved in developing immunization recommendations say that aspiration is not a necessary step in vaccine injections. Tell parents to provide their child with physical comfort (hold, hug) and use distraction (singing, talking, reading, playing with toys) to take a child's attention away from the procedure. Mothers can breastfed infants during the actual injection. Alternatively, infants can be given sugar water right before the injection. You can recommend topical anesthetics as well - they are particularly useful for school-age children that are anxious. Some of these strategies require planning, so it is ideal to educate parents about them beforehand.
[Back to Top]
Is egg allergy a contraindication to receiving the Pandemic (H1N1) 2009 vaccine?
The virus is grown in eggs and the vaccine may contain-minute amounts of egg products.
Persons with severe IgE mediated allergy (hives, mouth swelling, difficulty breathing, hypotension or shock) should have special precautions taken as recommended by the Canadian Society of Allergy and Clinical Immunology if the vaccine is administered.
Others with less serious egg allergies (mild gastrointestinal or mild local skin reaction, tolerating ingestion of small amounts of egg) can be vaccinated but the patient should be observed for 60 minutes after vaccine administration.
What are the likely side effects of the Pandemic (H1N1) 2009 vaccine?
Given what is known about seasonal influenza vaccine, earlier testing of the H5N1 bird flu adjuvant vaccine, and preliminary data with H1N1 2009 vaccine and that the antigen in the H1N1 2009 vaccine is similar to usual seasonal influenza, most people who receive the H1N1 2009 vaccine will experience some pain at the injection site and for some there will be tenderness for a day or two. A few people will develop a fever, and some will have muscle aches and pains for a few days.
[Back to Top]
What is an adjuvant? Why is there an adjuvant in Pandemic (H1N1) 2009 vaccine?
The H1N1 2009 vaccine comes in two parts: the antigen and the adjuvant. The antigen is a small amount of killed influenza H1N1 2009 virus that stimulates the body to develop immunity against the live H1N1 2009 virus. The adjuvant used is an oil-in-water solution that increases the immunogenicity of H1N1 2009 antigen so that less antigen is needed to achieve an equally effective vaccine.
What do we know about the safety of Pandemic (H1N1) 2009 vaccine?
Much is known about the safety of the seasonal influenza vaccines in all ages above 6 months and in pregnant women. The antigen in the seasonal influenza vaccine is very similar to the antigen in the H1N1 2009 vaccine and is prepared in the same way. For this reason scientists are confident about the safety of the antigen in the H1N1 2009 vaccine.
The H1N1 2009 non-adjuvant influenza vaccines have been given to several thousand people in clinical trials, and are now used in routine practice in the United States and in Australia. To date, these H1N1 2009 vaccines are as safe as the seasonal influenza vaccine.
The Canadian H1N1 2009 vaccine is similar to the vaccines being given in other parts of the world, except for the addition of the adjuvant.
[Back to Top]
What do we know about the safety of the adjuvant Pandemic (H1N1) 2009 vaccine?
Adjuvants have been used in hepatitis and pneumococcal vaccines in children with no apparent problems other than possibly a slight increased risk of local reactions. There is no reason to suspect they will cause any harm. Although adjuvants have not been used in routine influenza vaccines in the past, a study published in 2009 demonstrated the safety of an influenza vaccine with an adjuvant in children aged 6 to 24 months.
The H1N1 2009 vaccine being used in Canada is produced here by GlaxoSmithKline. Because this vaccine has not been used before, research has been done in Canada to test the safety of the vaccine with adjuvant.
We know a lot about the safety of the adjuvant used in this vaccine. The adjuvant has been tested in Canada with the H5N1 vaccine. There are no known short- or long- term serious harmful side effects associated with this adjuvant.
Most of the H1N1 2009 vaccine being used in the United Kingdom and in Europe has a similar or identical adjuvant in it.
By the time any vaccine is released in Canada, the manufacturer must carry out all steps to assure that the vaccine meets the high safety standards required for a new vaccine. Although the steps for the H1N1 2009 vaccine have been carried out in a shorter time than usual, none of the steps has been omitted.
[Back to Top]
When can the non-adjuvant Pandemic (H1N1) 2009 vaccine be used?
Pregnant women will be offered the non-adjuvant H1N1 2009 vaccine. The reason for this is a decision by the manufacturer not to test the adjuvant vaccine in pregnant women. Instead, they have tested a higher dose of killed influenza H1N1 2009 vaccine in pregnant women. Although there is no evidence in women that the adjuvant vaccine is less safe during pregnancy, the manufacturer decided to minimize additional drug exposure for pregnant women by offering them an adjuvant-free vaccine.
Some physicians have asked what can be done if a parent refuses to allow their young child to receive the H1N1 2009 adjuvant vaccine. The first step should be to reinforce the safety of the adjuvant vaccine. If the parent still refuses, then one possible solution maybe to give the non-adjuvented vaccine that is designated for use in pregnant women (expected by mid-November). However, it will be important that the correct amount of antigen be used: In the countries using nonadjuvented vaccine this is 7.5 micrograms per dose given in two doses separated by 3 to 4 weeks. This is a less than ideal situation as this would lead to delay in immunization, and non-adjuvented vaccine may not be available for use in this situation.
[Back to Top]
Is fever more common with the adjuvant Pandemic (H1N1) 2009 vaccine?
Some physicians are concerned about high fever with the adjuvant H1N1 2009 vaccine especially in young children. The rates of fever > 39o C in 3- to 5- year-olds in one small European study of this vaccine were about 4% with half dose and 10% with a full dose. These are higher rates of high fever than with usual seasonal influenza vaccine in this age group.
Both the regular seasonal influenza vaccine and the H1N1 2009 vaccine are “split virus” vaccines. This means they are made from killed virus that has been treated with organic solvent to remove surface glycoproteins so the product is less reactogenic, i.e., causes less fever and injection site reactions. The addition of the adjuvant may not only increase the immunogenicity of the vaccine but also may slightly increase the reactogenicity. More clinical information is needed to determine if this is correct.
[Back to Top]
How should fever with the adjuvant Pandemic (H1N1) 2009 vaccine be managed?
For the present, parents need to be informed of the potential of fever. Some experts suggest giving acetaminophen on receipt of this vaccine and then every 6 hours for a day.
A recent study in young children who were given acetaminophen following vaccination has shown a lower overall immune response in the children to a heptavalent vaccine. Most of the children who were vaccinated, however, still achieved a protective immune response. This suggests that the impact of acetominophen is small. Studies on the impact of acetominophen following vaccination with H1N1 2009 vaccine are not available at this time.
Some experts suggest using the nonadjuvent vaccine for younger children if it is available. The age cutoff will depend on availability and provincial and territorial protocols. Check with your local public health authority.
Given that children < 2 years old are at increased risk for serious illness with H1N1 2009 infection, the important point here is to ensure that these young children receive the H1N1 2009 vaccine.
[Back to Top]
What about Guillain-Barré Syndrome risk with influenza vaccine ?
Some have raised concerns that the H1N1 2009 vaccine may cause Guillain-Barré Syndrome (GBS), a disorder of the peripheral nervous system resulting in varying degrees of muscle weakness. Most patients fully recover from even the most severe form of Guillain-Barré syndrome, although some may continue to have some degree of weakness.
GBS is rare. In Canada, nationally 1 to 2 people per 100,000 develop GBS annually. In a study in Ontario and Quebec, the background incidence of GBS due to any cause was estimated at 2.02 per 100,000 person-years in Ontario and 2.30 per 100,000 person-years in Quebec.
Usually Guillain-Barré Syndrome occurs a few days or weeks after a person has a respiratory or gastrointestinal infection, including influenza. About two-thirds of patients with GBS in case series have a history of an infection in the 6 weeks before the GBS diagnosis. A variety of infectious agents, including Campylobacter jejuni , cytomegalovirus, Epstein-Barr virus and Mycoplasma pneumoniae, have been associated with GBS.
In 1976 because of a possible increased risk of GBS, the swine influenza vaccine was withdrawn. When this vaccine was given in 1976, there was an increase of 1 extra case of GBS per 100,000 people vaccinated but this increase in cases was not recognized until 45 million doses had been given. Some scientists believe GBS following the 1976 swine influenza vaccine was caused by the antigen. Other scientists believe that unrecognized Campylobacter gastrointestinal infection or other infection might have caused the increase in GBS and that the association with the vaccine was coincidental. Campylobacter is now recognized to be a common cause of GBS but this was not known in 1976, and was not tested for.
It is not known whether other influenza virus vaccines are associated with GBS. A retrospective review of the 1992-1993 and 1993-1994 U.S. influenza vaccine campaigns found an adjusted relative risk of 1.7 (95% CI 1.0 to 2.8; p = 0.04) for GBS associated with influenza vaccination. This is consistent with a more recent Canadian study involving a self-matched case series from the Ontario health care database for the years 1992 to 2004. This study found the estimated relative risk of hospitalization for GBS in the period 2 to 7 weeks after influenza vaccination, compared with the period 20 to 43 weeks after influenza vaccination, to be 1.45 (95% CI 1.05 to 1.99, p = 0.02). These studies suggest that the absolute risk of GBS in the period following vaccination is about one excess case per 1 million vaccines above the background GBS rate. The potential benefits of influenza vaccine must be weighed against this very low risk.
The H1N1 2009 virus is very different from the swine influenza virus of 1976 and the antigen in the H1N1 2009 vaccine is very different from the one used in the 1976 swine influenza vaccine.
Prior to giving large numbers of doses of vaccine, one cannot know for sure if there will be any increase in GBS cases with the H1N1 2009 vaccine. This event will be monitored closely over the next year. Canada has an excellent adverse events surveillance program for children. A similar surveillance program for adults has been developed. If there is any increase in GBS following H1N1 2009 vaccination, we should detect it quickly and able to respond accordingly.
[Back to Top]
Additional Reading and Useful Links
General Information about Influenza
Canadian Paediatric Society (CPS), Infection control in paediatric office settings. www.cps.ca/english/statements/ID/id08-03.htm (Version current at May 4, 2009).
Canadian Paediatric Society (CPS). The New Influenza A Virus: A/Mexico/2009 (H1N1) Practice Point for Caregivers of Children and Youth. http://www.cps.ca/english/statements/ID/H1N1Mexico2009.htm
Public Health Agency of Canada (PHAC). www.fightflu.ca and 1-800 O-Canada (1-800-622-6232)
US Center for Disease Control and Prevention (CDC), http://cdc.gov/h1n1flu/recommendations_pediatric_supplement.htm.
American Academy of Pediatrics (AAP), http://www.aap.org/new/AAP-Work-Group-CSHCN-H1N1-FINAL-10-1-09.pdf
US Centers for Disease Control and Prevention (CDC). Influenza-Associated Pediatric Mortality. http://www.cdc.gov/flu/weekly/index.htm#MS (Version current at October 15, 2009).
The ANZIC Influenza Investigators. Critical Care Services and 2009 H1N1 Influenza in Australia and New Zealand. N Engl J Med. 2009 [Epub ahead of print]
Bhat N, Wright JG, Broder KR, et al. Influenza-associated deaths among children in the United States, 2003-2004. N Engl J Med 2005;353:2559-67.
Chowell G, et al. Severe Respiratory Disease Concurrent with the Circulation with H1N1 Influenza. NRJM 2009;361:674-679.
Dodds L, McNeil SA, Fell DB, et al. Impact of influenza exposure on rates of hospital admissions and physician visits because of respiratory illness among pregnant women. CMAJ 2007;176:463-8.
ECDC Technical Emergency Team. Initial epidemiological findings in the European Union following the declaration of pandemic alert level 5 due to influenza A (H1N1). Euro Surveill. 2009;14(18):pii=19204
Izurieta HS, Thompson WW, Kramarz P, et al. Influenza and the rates of hospitalization for respiratory disease among infants and young children. N Engl J Med 2000;342:232-9.
Kumar A, Zarychanski R, Pinto R, et al. Critically Ill Patients With 2009 Influenza A(H1N1) Infection in Canada. JAMA. 2009 Oct 12. [Epub ahead of print]
Moore DL, Vaudry W, Scheifele DW, et al. Surveillance for influenza admissions among children hospitalized in Canadian Immunization Monitoring Program Active Centers. Pediatrics 2006;118:e610-19.
Rasmussen SA, Jamieson DJ, Bresee JS. Pandemic influenza and pregnant women. Emerg Infect Dis 2008;14:95-100.
[Back to Top]
Influenza Antiviral Information
Canadian Paediatric Society (CPS), The use of antiviral drugs for influenza: Recommended guidelines for practitioners
http://www.cps.ca/english/statements/ID/ID06-04.htm
Public Health Agency of Canada (PHAC). Interim Guidance for emergency use of oseltamivir (Tamiflu in children under one year of age in the context of 2009 (H1N1) pandemic.http://www.phac-aspc.gc.ca/alert-alerte/h1n1/guidance-orientation-07-20-eng.php
Public Health Agency of Canada (PHAC). Guidance for Ambulatory Care of Influenza-Like Illness in the context of H1N1 influenza virus.
http://www.phac-aspc.gc.ca/alert-alerte/h1n1/guidance-orientation-amb-07-16-eng.php
US Center for Disease Control and Prevention (CDC), http://www.cdc.gov/h1n1flu/eua/peramivir.htm
US Centers for Disease Control and Prevention (CDC).
http://www.cdc.gov/h1n1flu/recommendations_pediatric_supplement.htm
US Food and Drug Administration (FDA), Public Health Alert: Potential Medication Errors with Tamiflu for Oral Suspension. http://www.fda.gov/Drugs/DrugSafety/InformationbyDrugClass/ucm183649.htm
American Academy of Pediatrics (AAP). Committee on Infectious Diseases. Antiviral therapy and prophylaxis in influenza in children. Pediatrics 2007;119:852-860.
[Back to Top]
Influenza Vaccine Information
Public Health Agency of Canada. Canadian Immunization Guide Seventh Edition – 2006. Part 4. Active Immunizing Agents. Influenza Vaccine. http://www.phac-aspc.gc.ca/publicat/cig-gci/p04-inf-eng.php (Version current at October 15, 2009).
Institute of Medicine. Immunization safety review: influenza vaccines and neurological complications. http://books.nap.edu/openbook.php?record_id=10822 (Version current at October 15, 2009).
Carman WF, Elder AG, Wallace LA, et al. Effects of influenza vaccination of health-care workers on mortality of elderly people in long-term care: a randomized controlled trial. Lancet 2000;355:93-7.
Eisenberg KA, Szilagyi PG, Fairbrother G, et al.Vaccine Effectiveness Against
Laboratory-Confirmed Influenza in Children 6 to 59 Months of Age During the 2003–2004 and 2004–2005 Influenza Seasons. Pediatrics 2008; 122 :911- 19.
Halasa NB, Gerber MA, Chen Q, Wright PF, Edwards KM. Safety and immunogenicity of trivalent inactivated influenza vaccine in infants. J Infect Dis 2008;197:1448-54.
Hviid A, Stellfeld M, Wohlfahrt J, Melbye M. Association between thimerosal-containing vaccine and autism. JAMA 2003;290:1763-6.
MacDonald NE. Riley LE, Steinhoff MC. Influenza immunization in pregnancy. Obstet Gynecol 2009;114:365-8.
Neuzil KM, Zhu Y, Griffin MR, et al. Burden of interpandemic influenza in children younger than 5 years: a 25-year prospective study. J Infect Dis 2002;185:147-52.
Nichol KL. Efficacy and effectiveness of influenza vaccination. Vaccine 2008;26 Suppl 4:D17-22.
Zaman K, Roy E, Arifeen SE, et al. Effectiveness of Maternal Influenza Immunization in Mothers and Infants. N Engl J Med 2008;359:1555-64.
[Back to Top]
Appreciation
Portions of these question and answer materials have been adapted from Internet sources. American Academy of Pediatrics (AAP). Public Health Agency of Canada (PHAC). US Centers for Disease Control and Prevention (CDC).
We also acknowledge and appreciate the following individuals for contributing valuable information: Anna Taddio (Toronto), Mary Appleton (Halifax), and Francoise Bayles (Halifax).
[Back to Top]
INFECTIOUS DISEASES AND IMMUNIZATION COMMITTEE
Members: Drs. Robert Bortolussi, Halifax, Nova Scotia (chair); Jane Finlay, Richmond, British Columbia; Jane McDonald, Montreal, Quebec; Heather Onyett, Kingston, Ontario; Joan Robinson, Edmonton, Alberta; Elisabeth Rousseau-Harsany, Montreal, Quebec (board representative)
Liaison: Dr. Upton Allen, Toronto, Ontario (Canadian Pediatric AIDS Research Group); Dr. Charles Hui, Ottawa, Ontario (Committee to Advise on Tropical Medicine and Travel); Dr. Nicole Le Saux, Ottawa, Ontario (Immunization Monitoring Program, ACTive); Dr. Larry Pickering, Atlanta, Georgia (American Academy of Pediatrics); Dr. Marina Salvadori, London, Ontario (National Advisory Committee on Immunization)
Consultant: Dr. James Kellner, Calgary, Alberta; Dr. Noni MacDonald, Halifax, Nova Scotia; Dr. Dorothy Moore, Montreal, Quebec
Principal authors: Drs. Noni MacDonald, Halifax, Nova Scotia; Robert Bortolussi, Halifax, Nova Scotia; Upton Allen, Toronto, Ontario, and Heather Onyett, Kingston, Ontario.
[Back to Top]
Updated: December 21, 2009
|
