There are 2 types of pandemic H1N1 vaccine that are available for use in pregnant women:

1. Influenza A (H1N1) 2009 Monovalent Vaccine (Without Adjuvant) is the recommended vaccine for pregnant women. Panrix®H1N1 unadjuvanted vaccine from Australia will be available for pregnant females the week of November 2nd, followed by the Canadian supply later in November.
   
   
2. AREPANRIX™H1N1, ASO3-Adjuvanted H1N1 Pandemic Influenza Vaccine

What are the differences between these two vaccines?

The Influenza A (H1N1) 2009 Monovalent Vaccine (Without Adjuvant) has been developed the same way that is used every year to develop seasonal influenza vaccine.

The other vaccine, AREPANRIX™H1N1, was developed the same way as the annual seasonal influenza vaccine, but also uses an adjuvant called AS03.

What is an adjuvant?

An adjuvant is a substance that is added to a vaccine in order to boost the individual's response. It also means that less of the virus or "antigen" is needed to make a dose of the vaccine. The use of an adjuvant may also provide extra protection against future virus changes.

What is unadjuvanted?

Unadjuvanted vaccine has no "booster" element, and more antigen is needed to create this kind of vaccine.

Does an adjuvanted vaccine pose a risk to pregnant women?

All evidence suggests that adjuvanted vaccines are just as safe as unadjuvanted vaccines; however there is no safety data for the use of adjuvanted vaccine in pregnant women. The WHO's Strategic Advisory Group of Experts (SAGE) recommended in July that pregnant women should receive non-adjuvanted vaccine where possible, but that an adjuvanted vaccine could be used if necessary.

If H1N1 vaccine without adjuvant is not available at the time when increased H1N1 disease is seen in the community, the Public Health Agency of Canada has recommended that the adjuvanted H1N1 vaccine may be used in some pregnant women. This recommendation is based on the increased risk of complications from H1N1 disease in pregnancy.

What are the recommendations for pregnant females?

The unadjuvanted vaccine is recommended for all pregnant women at any stage of their pregnancy. However if the unadjuvanted vaccine is not available, some pregnant women should consider getting the adjuvanted vaccine.

• If you are more than 20 weeks pregnant, you are at greater risk for severe complications from the H1N1 flu. Your baby is also less likely to be affected by exposures to the vaccine since much of the critical development has already occurred. You should consider getting the adjuvanted vaccine that is available now. The potential benefit of early immunity to the H1N1 flu virus (from getting the vaccine) is greater than the possible risk of receiving the adjuvanted flu vaccine.
  
  
• If you are less than 20 weeks pregnant and have a chronic disease (like asthma or diabetes), you are also at greater risk for severe complications from the H1N1 flu. You should consider getting the adjuvanted vaccine that is available now. You should discuss this with your health care provider before receiving the vaccine.
  
  
• If you are less than 20 weeks pregnant, and are healthy, you can wait to get the unadjuvanted vaccine. You are less likely than women in late stages of pregnancy or women with severe chronic disease to develop complications from influenza. Get the unadjuvanted vaccine as soon as it becomes available to you.

What is the risk of H1N1 disease if I am pregnant?

Pregnant women are not more likely to get the flu, but if they do catch the H1N1 flu virus, they are more likely to suffer complications, like pneumonia and severe respiratory distress, which can put both mother and baby's health at risk. Severe complications from the flu could lead to early delivery or miscarriage. The risk of complications is greater in the second and third trimesters of pregnancy.

Immunization while pregnant may also help to protect the infant after birth, since infants under 6 months of age are also at higher risk of complications from the H1N1 flu virus, but cannot receive the H1N1 vaccine.

Adapted from Public Health Agency of Canada, Nov. 1, 2009