Breaking the barriers to childhood influenza vaccination

“Prevention is so much better than healing, because it saves the labour of being sick.” Thomas Adams (1629)

No public health measure in the history of medicine has been more effective against infectious diseases than vaccination. Paediatricians and physicians who care for children must take credit for the implementation and success of international vaccination programs, with the exception of influenza in North America. Vaccination against influenza virus has been associated with the lowest compliance rate of any recommended vaccine for children. It is estimated that only 1% to 7% of those children recommended for yearly influenza vaccination actually receive the vaccine. Several reasons for this poor track record exist that relate to the characteristics of the virus, the epidemiological pattern of the infection and to the attitudes of physicians who administer the vaccine.

The efficacy of influenza vaccine has been difficult to assess, and this may have affected physicians’ decision to vaccinate children. But there are now excellent efficacy and effectiveness data, mainly from adults with an increasing number of studies involving children, showing that influenza vaccine protects against influenza illness (1). The ability of the influenza virus to undergo rapid structural changes through mutation and the problems with expeditious vaccine production means appropriate strains for the vaccine are selected a year before the vaccine is needed. Information is provided by a worldwide surveillance network, and when there is a good fit between the strains included in the vaccine and the circulating virus, as usually occurs, the inactivated vaccine is 70% to 90% effective in preventing disease in people under age 65 years (1). When an unexpected strain of influenza virus occurs in a particular year that was not included in the vaccine for that year, such as the H3N2/Sydney strain in 1997/98, it reduces the efficacy of the vaccine (2).

Children and young adults have the highest frequency of illness (3), yet one of the reasons cited for not using the influenza vaccine is the belief that influenza is not associated with much morbidity or mortality in this age group. Both healthy children and those with underlying high risk conditions are significantly affected during interepidemic years as well as epidemic years. Attack rates in healthy children have been estimated at 10% to 40% each year, and approximately 1% of these infections result in hospitalization. Otitis media, often bacterial in etiology, occurs in 10% to 50% of influenza infections. The risk of pneumonia and bronchiolitis ranges from 0.2% to 25% (4). Studies of hospitalized children with influenza infection have suggested a mortality rate of 1% to 4%, and in many affected children, systems other than the respiratory tract have been involved (5).

Of all barriers to successful influenza vaccination, none is greater than the attitude of physicians. In a recent survey of 315 Ontario physicians (6), only 44% indicated that they were vaccinated against influenza, despite the recommended guidelines that health care personnel in both hospitals and the community be vaccinated to prevent influenza’s spread to the children in their care. Nearly one-third of the physicians that reported themselves unvaccinated were “too busy” to be vaccinated, and over half did not perceive a need. It may be difficult for physicians to implement a vaccination program if they are not committed to following published guidelines. The importance of physician attitude cannot be underestimated because it is believed that physician advice is the most important factor influencing the decision by parents to have their children vaccinated (7).

Community paediatricians lead both family physicians and subspecialty paediatricians when it comes to over-coming other barriers to successful influenza vaccination (6). Community paediatricians are significantly more likely than the other two groups to administer vaccination for most of the recommended high risk paediatric conditions, and are more likely to use active strategies to contact families of high risk children. Surprisingly, less than 50% of subspecialists recommend vaccination, even though the majority of high risk patients are seen in the hospital setting. This may be partially explained by the fact that almost half of all subspecialists feel that vaccination is the responsibility of the primary care physician. This belief likely gives rise to, but does not excuse the limited efforts (active and passive) of subspecialists to notify families or patients that they require vaccination, or to initiate vaccination directly. Ideally, high risk patients should be identified by hospital-based subspecialists, permitting the establishment of a computer database of ‘at risk children’ for whom annual influenza vaccination can be recommended. The vaccine can be administered either at the hospital or by their primary care physician (based on the family’s preference). Indeed, 83% of all physicians surveyed feel that hospitals should have a specific policy for recommending and implementing influenza vaccination for high risk children, a strategy that has already been successfully implemented at some institutions.

Successful influenza vaccination programs need to combine several strategies to be effective: education for health care workers including efforts to address common concerns about effectiveness and adverse reactions, publicity and education targeted toward potential recipients particularly in high risk areas, such as cardiac, pulmonary, hematology and cancer clinics; a plan for identifying children at high risk; and efforts to remove administrative barriers and increase accessibility of immunization clinics. Fortunately, in Canada, we have no financial barriers to influenza vaccination for designated high risk individuals; however, there are differences among provinces regarding eligibility for vaccination (8). Other suggested strategies to help implement a successful vaccination program include standing order policies in institutions allowing nurses to administer vaccines, vaccinating high risk patients upon discharge from hospitals, emergency rooms or ambulatory clinics in the fall of each year, patient-carried reminder cards and vaccination fairs.

The current guidelines give no consideration to vaccination of healthy children, children in day care centres or those with recurrent otitis media, even though there is some evidence that otherwise healthy children might benefit from influenza vaccination. In a recent study, healthy children vaccinated with the new intranasal, live attenuated, cold-adapted influenza virus vaccine, had a 35% reduction in the incidence of febrile otitis media with concomitant antibiotic use and a 29% reduction in the incidence of any febrile illness with concomitant antibiotic use. The vaccine efficacy was 93% against culture confirmed influenza (9). In this era of increasing antibiotic resistance associated with excessive antibiotic exposure, influenza vaccination may become an increasingly important strategy to diminish febrile illnesses for which antibiotics may be needed.

Universal intranasal childhood influenza vaccination has been proposed as the way of the future because this strategy is expected to not only reduce wintertime paediatric out-patient morbidity and paediatric hospitalization but also to affect the community spread of disease (10). It is known that the presence of a child in the home is associated with a greater risk of influenza infection in adults. Therefore, a broad and effective intervention program such as universal childhood vaccination might have a significant impact on the community spread of the disease and improve the overall effectiveness of influenza immunization. The new nasally delivered, live attenuated influenza vaccine also avoids the unpleasant prospect for children and physicians of yearly painful influenza needle sticks.

Until the intranasal influenza virus vaccine becomes available for routine use, physicians are urged to implement vaccination against influenza according to current published guidelines (11), summarized in Table 1.

TABLE 1:

Recommended recipients for the prevention and control of influenza in children during the 1998/99 influenza season

Children at high risk Children with chronic cardiac or pulmonary disorders (including bronchopulmonary, dysplasia, cystic fibrosis and asthma) severe enough to require regular medical follow-up or hospital care Children with chronic conditions, such as diabetes mellitus and other metabolic diseases, cancer, immunodeficiency, immunosuppression (due to underlying disease and/or therapy), renal disease, anemia and hemoglobinopathy Children and adolescents with conditions treated for long periods with acetylsalicylic acid Children who are residents of chronic care facilities People capable of transmitting influenza to those children at high risk Health care workers and other personnel who have significant contact with children in high risk groups including health care workers in long term care facilities, hospitals and out-patient settings Household contacts (including children) of people at high risk who either cannot be vaccinated or may respond inadequately to vaccination