Pandemic H1N1 vaccine – Common questions

Question categories

Questions about vaccine use

1. Who would benefit most from being immunized for pandemic H1N1 influenza?

Receiving the Pandemic (H1N1) 2009 influenza vaccine is one of the most effective ways to prevent the spread of the virus. Immunizing as many Albertans as possible can reduce the spread to vulnerable populations who are at greater risk of complications from the pandemic H1N1 influenza virus.

H1N1 immunization is available to all Albertans six months of age and older. Those who will benefit most from immunization and those who care for them should receive the vaccine, including:

  • Pregnant women;
  • Children six months to less than five years of age;
  • People under 65 with chronic health conditions;
  • People living in remote and isolated settings or communities; and
  • Health care workers involved in pandemic response or the delivery of essential health care services.

Consult with your health-care provider if you are at risk for complications and if you have even mild influenza symptoms.

2. Are Aboriginal people included in the priority list?

  • At risk Aboriginal people are captured in the priority groups outlined in Question 1.
  • For example, many Aboriginal populations have higher numbers of pregnant women, higher rates of diagnosed and possibly undiagnosed chronic disease, and may live in remote and isolated communities.
  • All efforts will be made to enable those Aboriginal people to have access to the H1N1 vaccine as soon as it becomes available wherever they reside, especially those who would benefit most from immunization.

3. What are the H1N1 vaccine recommendations for children?

  • All children over six months and under three years should get a second pediatric dose after the initial dose. The second dose should be at least 21 days after the first dose.
  • Children with chronic medical conditions ages three to under 10 years old should get a second pediatric dose after the initial dose. The second dose should be at least 21 days after the first dose.
  • Healthy children, ages 3–9 years old, should receive only one dose, until further notice.

4. Which vaccine is recommended for pregnant women?

The preferred Pandemic (H1N1) 2009 influenza vaccine for pregnant women is the unadjuvanted vaccine because there is more safety information currently available on the unadjuvanted vaccine in pregnant women.

Women who are more than 20 weeks pregnant and those in earlier stages of pregnancy who have serious underlying medical conditions (such as severe asthma, diabetes, chronic lung or heart disease, etc.) can get the adjuvanted vaccine, if they choose. This is considered safe by the World Health Organization and Canada's Chief Public Health Officer. However, the unadjuvanted vaccine is the preferred option.

5. What is the adjuvanted vaccine? What is the difference between adjuvanted and non-adjuvanted?

An adjuvant is an all-natural substance that is added to a vaccine in order to boost the individual’s immune response against the influenza virus. The addition of an adjuvant may also give some cross protection from different strains if the virus changes slightly from the strain used to make the vaccine. It also means that less of the virus or “antigen” is needed to make a dose of the vaccine. Non-adjuvanted vaccine has no “booster” element, and more antigen is needed to create a similar immune response as the adjuvanted.

For the purposes of controlling an influenza pandemic and having enough vaccine for the entire world, the WHO has recommended that countries use dose-sparing strategies whenever possible. By developing an adjuvanted vaccine, we use less of the virus material (antigen), allowing us to immunize more people in a timely manner.

6. How long does it take after I get the pandemic H1N1 influenza vaccine before I am protected?

Responses differ from person to person, but in general the immune response begins within three to five days and full protection occurs within 10–14 days of immunization for most people.

7. If I had pandemic H1N1 influenza disease do I need to get the vaccine?

  • Unless your illness was lab confirmed, you do not know for certain which strain of the virus infected you. You should receive the vaccine.
  • Even if the infection you had was H1N1, the result would be a further boost in immunity (antibodies) and no increased risk for adverse events following immunization.

8. How long do I have to wait after my seasonal influenza immunization before I can get the H1N1 vaccine?

No interval is necessary between seasonal influenza vaccine and Pandemic (H1N1) 2009 influenza vaccine, regardless of the order administered.

  • We encourage every Albertan over the age of six months of age to be immunized against H1N1 as early as possible, including those who have recently been immunized against seasonal influenza.

9. Who should not be immunized with the Pandemic (H1N1) 2009 influenza vaccine?

  • Children under six months of age.
  • People who have had a previous anaphylactic (sever allergic reaction) to any element of the vaccine.
  • People with severe hypersensitivity to eggs (e.g. hives, swelling of the mouth and/or throat, breathing difficulty).
  • People experiencing a high fever.
  • People who have previously experienced Guillain-Barré Syndrome within eight weeks of receiving a seasonal influenza vaccine.

10. Can I receive H1N1 vaccine in Alberta if I am not a permanent resident of the province?

Yes. Canada has purchased enough vaccine to immunize all persons that live, work or go to school in Canada. Therefore, persons visiting from other provinces/territories in Canada will be able to receive immunization for H1N1 influenza while in Alberta.

  • Persons visiting that do not live, work or go to school in Canada will not be eligible to receive H1N1 influenza vaccine in Alberta.

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Questions about vaccine safety

11. What is the approval process for vaccines?

  • Canada, like other jurisdictions worldwide, exercises tight regulatory oversight over vaccines because they are given to large numbers of healthy individuals.
  • New vaccines are authorized in Canada following the review of the evidence in support of the quality, safety, and protectiveness of the vaccine. It also requires on-site inspection of the manufacturing facilities, and testing in Health Canada laboratories.
  • Health Canada tests samples of each lot of a licensed vaccine before authorizing the manufacturer to release that lot for sale in Canada.
  • All provinces monitor for and report any serious adverse reactions to vaccines. Serious adverse reactions are investigated.
  • No steps in the vaccine approval process were missed for the Pandemic (H1N1) 2009 vaccine.

12. What about the side effects from the pandemic H1N1 vaccine?

  • Side effects are expected to be similar to those observed with seasonal influenza vaccines.
    • Common side effects include local reactions at the injection site (soreness, swelling, redness) and possibly some systemic reactions (fever, headache, muscle or joint aches).
  • In the vast majority of vaccine recipients, these symptoms are mild, and last one to two days.

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Questions about vaccine components

13. Does the pandemic H1N1 influenza vaccine contain latex/egg?

  • The vaccine does not contain latex. The rubber stopper on the vial is made of butyl rubber and is latex free.
  • The vaccine is grown in eggs and should not be given to anyone who is severely allergic to eggs.

14. Does the vaccine contain thimerosal?

Yes. Each 0.5ml dose of adjuvanted vaccine contains a very small amount of thimerosal, only 5µg – that means, only five micrograms or 5/1000 of a milligram. It is a mercury derivative used as a preservative. A preservative is necessary in multi-dose vials according to the World Health Organization's guidelines and thimerosal remains the most effective preservative. Each 0.5ml dose of unadjuvanted vaccine contains 50µg of thimerosal.

  • There is no reason to avoid using vaccines containing thimerosal. The best available scientific evidence to date shows no link between thimerosal-containing vaccines and any adverse health condition, including neurodevelopmental disorders like autism.

15. Will a thimerosal-free Pandemic (H1N1) 2009 influenza vaccine be available?

No. There will not be a thimerosal-free Pandemic (H1N1) influenza vaccine available.

  • There is no reason to avoid using vaccines containing thimerosal. The best available scientific evidence to date shows no link between thimerosal-containing vaccines and any adverse health condition, including neurodevelopmental disorders like autism.

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Questions about the adjuvant

16. What is the difference between adjuvanted and non-adjuvanted vaccine?

  • An adjuvant is a substance that is added to a vaccine in order to boost the individual’s immune response. It also means that less of the actual virus or “antigen” is needed to make a dose of the vaccine.
  • Non-adjuvanted vaccine has no “booster” element, and more antigen is needed to create a similar immune response as the adjuvanted vaccine.

17. Why is there an adjuvant in the Pandemic (H1N1) 2009 vaccine that will be used in Canada?

The World Health Organization (WHO) has recommended that countries use dose-sparing vaccines whenever possible to ensure there is enough vaccine for the entire world. By using an adjuvanted vaccine, we use less of the virus material (antigen). Current clinical evidence shows that an adjuvanted vaccine is safe and will also help cause a stronger immune response, protect more quickly, and give better protection if the influenza pandemic virus changes slightly.

18. How common are adjuvants used in a vaccine?

  • Adjuvants are not new. They have been used for several decades to boost immune response to vaccines.
  • Many of the commonly used vaccines in Canada (e.g. pertussis, tetanus, diphtheria haemophilus influenza type b) contain an adjuvant.
  • Adjuvants have not previously been used with influenza vaccines in Canada.

19. If I have an allergy to fish can I still receive the pandemic H1N1 influenza vaccine?

Squalene is a component of the adjuvant included in the pandemic H1N1 influenza vaccine. It is added to vaccines to enhance the immune response and is a naturally occurring substance found in plants, animals and humans. It is synthesized in the liver and circulates in the human bloodstream. It is therefore not considered an allergenic substance.

  • However, persons with severe fish allergies may wish to be immunized in a controlled setting either via their family physician or an allergy clinic in order to ensure immediate urgent care is available should they experience any reaction to the vaccine.
  • Alternately, you may want to consider the unadjuvanted vaccine (pending availability) which does not contain squalene.

20. How do you know the adjuvant is safe?

The adjuvant used in the Pandemic (H1N1) 2009 influenza vaccine is similar to another adjuvant used to produce the seasonal influenza used to immunize over 40 million people in other countries and to date, tens of thousands of people have received vaccines containing the same adjuvant in this H1N1 vaccine in clinical trials and no major safety issues have surfaced.

More information

More information on H1N1 can be found at:

Call Health Link Alberta

If you are sick or caring for somebody who is sick and need immediate advice, call Health Link Alberta:

  • In Calgary, 403-943-5465
  • In Edmonton, 780-408-5465
  • Toll free 1-866-408-5465 in Alberta

The Health Link Alberta phone is answered by registered nurses 24 hours a day, 365 days a year.

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Updated December 1, 2009