To determine physician-administered influenza vaccine coverage for children aged 6 to 23 months in a jurisdiction with a universal influenza immunization program during 2002–2009 and to describe predictors of vaccination.
By using hospital records, we identified all infants born alive in Ontario hospitals from April 2002 through March 2008. Immunization status was ascertained by linkage to physician billing data. Children were categorized as fully, partially, or not immunized depending on the number and timing of vaccines administered. Generalized linear mixed models determined the association between immunization status and infant, physician, and maternal characteristics.
Influenza immunization was low for the first influenza season of the study period (1% fully immunized during the 2002–2003 season), increased for the following 3 seasons (7% to 9%), but then declined (4% to 6% fully immunized during the 2006–2007 to 2008–2009 seasons). Children with chronic conditions or low birth weight were more likely to be immunized. Maternal influenza immunization (adjusted odds ratio 4.31; 95% confidence interval 4.21–4.40), having a pediatrician as the primary care practitioner (adjusted odds ratio 1.85; 95% confidence interval 1.68–2.04), high visit rates, and better continuity of care were all significantly associated with full immunization, whereas measures of social disadvantage were associated with nonimmunization. Low birth weight infants discharged from neonatal care in the winter were more likely to be immunized.
Influenza vaccine coverage among children aged 6 to 23 months in Ontario is low, despite a universal vaccination program and high primary care visit rates. Interventions to improve coverage should target both physicians and families.
Campitelli et al. (1) shed light on an important issue within public health, that being uptake of the influenza vaccine in a high-risk population. Given the presence of studies (2) showing that living in Ontario granted an increased chance of having received the flu shot, it is likely that rates are even lower in the rest of the country and potentially in other districts without a universal influenza immunization program. It is puzzling that such a small proportion of the eligible population, particularly those at increased risk of serious complications of the disease, choose to take advantage of this protective measure. I would like to further explore some factors that might affect vaccine usage by considering the disease and its potential consequences, followed by a discussion of barriers to vaccine use and finally conclude with some suggestions as to how an increase in vaccination rates might be facilitated.
Influenza may cause a wide spectrum of disease, the clinical manifestations of which are often self-limiting but which may become severe, particularly in the elderly, those with chronic disease or the very young (3). A 2006 American study (4), for instance, revealed an annual rate of hospitalization of 90 per 100,000 children, with a far greater number of outpatient or clinic visits attributable to the disease. Though the severity of illness and impact on daily activity can vary by person and season it can be associated with such disparate effects as acute otitis media, asthma exacerbation, pneumonia , secondary bacterial infections and other, rarer, disease complications like encephalopathy (5). Children might suffer unnecessary procedures in an effort to investigate the illness (6). Given that vaccination has been shown to have modest efficacy in reducing influenza-like illness in adults (7) and children over two years (8) with observational studies (9, for example) pointing to decreases in morbidity and mortality, offering immunization, particularly to persons at high-risk (10), seems sensible. Uptake, however, even in a population at risk of serious complications from the disease, is underwhelming. There must, then, be barriers to its acceptance.
One reason vaccines are sometimes viewed with suspicion is that they are given to healthy people to prevent a threat that has yet to materialize and might reasonably never do so (11); the results of vaccination are not as obvious as, say, those of providing an antifungal to clear a rash. In the case of young children, their receiving the immunization depends entirely on their caregivers' acceptance of its utility. Such confidence can easily be shaken, particularly when the vaccination is against a disease that is sometimes considered to be relatively benign. As an example, Australian guidelines recommend that the elderly, those with chronic disease, pregnant women and those with increased risk of contracting influenza receive the vaccination. In 2008 Western Australia went beyond these guidelines, implementing universal influenza vaccination for all children from the ages of 6 months to 5 years (12). Unfortunately, in 2010, a higher-than-expected incidence of febrile convulsions occurred; these were ultimately associated with one particular brand of the vaccine (13). Though the program was suspended until an investigation (14) was completed and the offending brand afterwards contraindicated in young children, such incidents have the potential to dramatically reduce vaccination rates in general, as evidenced by the measles-mumps-rubella scare (15) suggests. Studies (16, 17) attempting to clarify various themes as to why influenza vaccination might be rejected described broad categories including: fear, misinformation, mistrust, consideration of necessity and inconvenience. Fear encompasses both the perception that it might cause more harm than good and the belief that the injection is painful and might hurt the child, or perhaps simply that the person fears needles in general.
Misinformation is readily available on the internet (18) and a person's family members and friends are often quite willing to share their opinions - good or bad - on the flu shot. As for necessity, a person might believe that influenza is not a serious illness or that it can and should be dealt with by the child's immune system without the assistance of a vaccine. Inconvenience might be as simple as not being able to afford the vaccine (a problem which is perhaps not relevant to Ontario residents) or not having time to drive one's child to a clinic for the injection. Studies have also examined factors that facilitate vaccine uptake.
These included both the removal of hurdles to as well as perceived benefits of immunization. Motivating influences include the prevention of disease in a high-risk family member, vaccination being offered or mandated by the child's school, vaccination being free of charge - this being a key factor in the utility of a universally-available vaccination program, prominent public health campaigns (19), electronic reminders, being able to receive the vaccination at a convenient location (20) and recommendation by a trusted person - particularly one's physician (16). The role of the health care provider in advocating vaccination should not be understated. By tailoring communication strategies to particular groups practitioners can become powerful advocates for an important aspect of patient health (21). Having a system to remind patients to present for vaccination and then provide it to them was associated with increased vaccination rates among patients of a group of general practitioners in the UK (22). A particularly simple manner in which practitioners might promote vaccination is to receive it themselves: some studies have shown surprisingly low uptake amongst health care professionals (23, 24): it is hardly unreasonable for patient to be hesitant to accept an immunization if his doctor does not get it himself.
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Conflict of Interest:
None declared