Influenza vaccine recommendations for children and youth for the 2011/2012 season

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The National Advisory Committee on Immunization and the Canadian Paediatric Society encourage annual influenza vaccination for ALL children and youth six months of age and older. When this is not practical, priority should be given to individuals at high risk of influenza-related complications and to those capable of transmitting infection to individuals at high risk of complications. This group includes the following:

• Children six to 23 months of age;

• Members of households expecting a newborn during influenza season;

• Pregnant women, for their own protection and to protect their newborn infant;

• Children with cardiac or pulmonary disorders including risk of aspiration, cystic fibrosis or asthma, and children with other chronic conditions including diabetes mellitus, metabolic diseases, renal disease, anemia and hemoglobinopathies;

• Children with cancer or illness-associated immunodeficiency or immune suppression;

• Children treated for long periods with acetylsalicylic acid;

• Children with morbid obesity;

• Aboriginal children; and

• Residents of chronic care facilities.

Adults and children who are household contacts of individuals at high risk, or their caregivers, and all health care providers, should also be immunized.

The three antigenic components of the influenza vaccine are unchanged from last year’s vaccine. Although some vaccinated individuals will retain immunity from one season to the next, not all individuals will. It is, therefore, recommended that everyone be revaccinated, even if they received vaccine or had documented influenza last year.

A major change is that the National Advisory Committee on Immunization is now recommending that all age groups, including children six to 35 months of age, receive 0.5 mL per dose of influenza vaccine (1). This recommendation replaces previous guidance suggesting that these children receive 0.25 mL per dose. The rationale for this change is the demonstration of a modest improvement in immunity with the 0.5 mL dose compared with the 0.25 mL dose, without any increase in adverse effects.

The first year that children younger than nine years of age receive influenza immunization, two doses are required to achieve protection. The doses are administered at least four weeks apart, and both doses should be 0.5 mL. If a child younger than nine years of age received one influenza immunization last season (2010/2011), only one immunization is required this season.

FluMist (Medimmune, USA) is an intranasal, live attenuated vaccine (2). Multiple studies demonstrate a statistically significant superior efficacy of FluMist over injectable, trivalent, inactivated influenza vaccine against culture-confirmed influenza in children. Important side effects include mild rhinitis in most recipients and exacerbations of wheezing in those with severe asthma. This year, the National Advisory Committee on Immunization is preferentially recommending FluMist for healthy children and youth two to 17 years of age. However, it is very unlikely that this vaccine will be easily available through publicly funded programs because of supply and contract issues. FluMist is contraindicated for people with immune-compromising conditions or severe asthma (defined as active wheezing or current use of inhaled or oral glucocorticosteroids), and those with medically attended wheezing in the seven days before vaccination.

For patients with an egg allergy, please see the recent Canadian Paediatric Society position statement on this subject at <http://www.cps.ca/english/statements/ID/ID11-06.htm> (3).