Influenza update: NACI issues annual influenza prevention recommendations for the 2006/2007 season

Abstract

As children return to school and summer vacations end, public health authorities and vaccine providers must turn their thoughts to ensuring that annual fall influenza vaccine program plans are in place. The National Advisory Committee on Immunization (NACI) statement on influenza immunization for the 2006/2007 season was published on June 15, 2006 (1) and can be found on the Internet at . We review those recommendations that apply to children and youth, and to the health care providers who take care of them. In Canada, the first-line strategy to reduce the burden of illness associated with influenza virus infection is a vaccine strategy based on risk, rather than a universal approach. Those subpopulations recognized to be at higher risk for complications of influenza, such as pneumonia or exacerbation of underlying cardiac, pulmonary or metabolic disease, are targeted for immunization, whereas healthy persons are encouraged, rather than recommended, to receive vaccine. In general, provincial and territorial authorities fund programs to deliver influenza vaccine to recommended recipients, either through individual physicians or through public health programs, but do not underwrite the cost of vaccine for others. The exceptions to this are Ontario and the Yukon, both of which offer universal programs for their entire population. The children and youth that are recommended recipients in the 2006/2007 guidelines are those with any of the following risk factors: Chronic cardiac or pulmonary disorders severe enough to require regular medical follow-up or hospital care (including bronchopulmonary dysplasia, cystic fibrosis and asthma). Residence in a nursing home or other chronic care facility. Diabetes mellitus and other metabolic diseases, cancer, immunodeficiency, immunosuppression (due to underlying disease and/or therapy), renal disease, anemia or hemoglobinopathy. Any condition that compromises the ability to manage respiratory secretions and is associated with an increased risk of aspiration. Healthy infants aged six to 23 months. Having a condition that has been treated for a long period of time with acetylsalicylic acid. Any individual at high risk of influenza complications (as outlined above) embarking on travel to destinations where influenza is likely to be circulating. There were no new paediatric age groups added to the list of recommended recipients this year. Paediatricians will recall that last year, healthy infants aged six to 23 months, as well as their care providers, were added to those recognized to be at high risk because of their high risk of hospitalization with influenza. This year, the United States Advisory Committee on Immunization Practices extended immunization from 23 months to 59 months of age because of their increased risk for visits to influenza-associated clinics, emergency departments and hospitals (2). Although vaccine efficacy varies with influenza strain, match and host, it is estimated that inactivated influenza vaccines reduce the risk of influenza in children by approximately 65% (3). The second major group of recommended recipients for annual influenza vaccine comprises individuals capable of transmitting influenza to high-risk populations. Thus, paediatricians and other members of the health care team in office or institutional settings are recommended recipients for influenza vaccine. The complete list is as follows: Health care and other care providers in facilities and community settings who, through their activities, are potentially capable of transmitting influenza to those at high risk of influenza complications. Household contacts (adults and children) of people at high risk of influenza complications, whether or not they have been immunized. These persons include household contacts of children six months of age or younger (who are at high risk of complications from influenza but for whom there is no available effective vaccine) and of children aged six to 23 months. Pregnant women should be immunized in their third trimester if they are expected to deliver during influenza season, as they will become household contacts of their newborn. Those providing regular child care to children 23 months of age or younger, whether in or out of the home. In this year’s statement, the NACI is emphasizing the importance of immunizing pregnant women with risk factors for complicated influenza, and is encouraging vaccination for all pregnant women. Paediatricians are likely to be in contact with many individuals in this target group, and play an important role in educating parents even though they may not deliver care to this population. Paediatricians may also serve as consultants to schools, out-of-home child care settings, and institutions providing residential care for children and youth, and can advocate for immunization of health care and other care providers. The NACI also provides recommendations on the use of antiviral drugs for the prevention of influenza. Notably, only neuraminidase inhibitors are recommended for this purpose in 2006/2007. Antiviral susceptibility testing indicates that at least 80% of Canadian influenza isolates were resistant to amantadine in 2005/2006. The only approved drug in this class for antiviral prophylaxis is oseltamivir, which is supplied in both a capsule and liquid paediatric formulation. Antiviral prophylaxis is employed in institutions where outbreaks occur, including residential settings, or for exposed persons to whom vaccine cannot be given (eg, previous anaphylactic allergy) or who could have inadequate immune response (eg, immune compromised). The epidemiology of the 2005/2006 influenza season is also reviewed in the NACI statement. Of interest to paediatricians, almost one-half (44.6%) of laboratory-confirmed influenza infections reported in Canada last year occurred in children younger than 15 years of age, while 17.0% were in adults at least 65 years of age. This, coupled with accumulating data that the full burden of influenza is not recognized in children (4), underlines the importance of advocacy for, and implementation of, influenza vaccine programs for children and youth, as well as those with whom they will be in close contact.