Our study shows that receiving a specific recommendation for influenza immunization by any physician is a single strong determinant of influenza immunization uptake in children with chronic diseases. This positive influence is independent from socio-demographic characteristics, number of contacts with health providers, and underlying disease.
We found that immunization coverage in children with chronic conditions substantially changes depending on the underlying disease, as already observed , despite all participants in the study belonged to categories addressed by international guidelines on influenza immunization . Patients with neurological disorders had the lowest immunization coverage and they were those with the lowest recommendation level. This finding might be explained by different perceptions of influenza infection severity in different chronic conditions by health professionals, as observed for neurological disorders and type 1 diabetes in other studies [24, 25].
Many studies focused on barriers to immunization and on multilevel interventions to increase vaccination coverage in healthy and chronic patients . Strong scientific evidence exists showing that multicomponent interventions including education are effective in improving immunization coverage . Physicians willingness and capabilities to recommend vaccinations are affected by the perceived relevance of the vaccines, by knowledge on their contraindications, by the health care system organization, and by communication between providers [26, 27]. Also non-integrated interventions may be effective in improving immunization coverage in children with chronic conditions, but the evidence is weak . Multicomponent interventions including reminder systems or other educational initiatives were not in place in our setting. Increasing the ability to provide a recommendation toward immunization by physicians may represent therefore a simple and efficacious strategy in settings where multicomponent interventions are not in place.
Different health providers are involved in the management of children with chronic conditions and multiple contacts with different specialists may result in different paths from recommendation to vaccine administration. We focused on the health providers that most frequently are in contact with these children in the Italian setting and whose recommendation may influence their decision to receive influenza immunization. We found that having received a recommendation by any health provider is associated with an increased likelihood of receiving influenza immunization. Since health professionals included in our analysis may provide recommendation and administer influenza vaccines as well, we investigated the path from recommendation to vaccination administration that these children followed. Although the number of visits by a certain provider is not associated with immunization uptake, families of patients with chronic diseases refer most frequently to specialty and family pediatricians. Given that recommendation to immunize is highly effective, increasing the frequency of recommendation by health providers may substantially change immunization uptake.
This study had several strengths and limitations. We did not select a sample of clinics in each Region but we rather selected the largest Reference Centers for the chronic diseases considered in the study. Although our study was conducted on a heterogeneous population of children with different chronic diseases whose information on immunization was carefully reviewed, it is likely that we selected families with a high level of attention to their child’s disease. It must be underlined that the follow up for chronic diseases is entirely free of charge in the Italian health care system and usually large reference centres concentrate the largest population of children with chronic diseases in their catchment area. Moreover, it is of note that families frequently reported having received a recommendation to immunize against influenza by different health providers, and that the effect of these recommendations is strong as well. Although we allowed participation in the study only to families who brought in their immunization card, we do not feel that this may have led to a significant bias since their number was negligible. Patients in charge to reference centers enrolled in the study were strictly monitored for at least six months and they were reminded to bring in their immunization card at each appointment.
We included in the study only a group of chronic disease that we believe representative but we excluded some common diseases such as asthma. While asthma is the most common chronic condition in childhood for which influenza vaccine is recommended, we felt it would deserve a specific study to investigate determinants of influenza immunization.
Finally, we might have interviewed, in each health care centers, patients routinely visited by a single physician, whose behavior may not reflect the behavior of the entire team of physicians in the same clinic. However, the specialty clinics included in the study include a large number of physicians on duty, with a high turnover; moreover, we performed our weekly interviews in different weekdays, reducing the probability of meeting patients referring to the same physician.
Since information on recommendation was collected through interviews, this may be subject to recall bias and those who received influenza immunization may better recall having received a recommendation. However, although reporting bias is probable, it is unlikely that such a strong association is explained by these biases, and, therefore we believe that medical recommendations are essential to improve immunization coverage.
Finally, we cannot say if our results are applicable to other countries and settings. However, since the number of health providers in contact with families of children with chronic diseases is high, it may well be that recommendation toward influenza immunization may be provided at multiple levels in other settings. Hence, similar studies should be conducted in other settings for confirming the results.