Журнал «Актуальная инфектология» 1 (6) 2015

The emergence and spread of 2009 pandemic influenza A (H1N1) virus has showed necessity of rapid actions and prophylaxis of the infection. Vaccination with influenza vaccine remains the key strategy for the prevention of influenza infection and reducing the severity of disease [1,2]. Influenza vaccination in children is especially significant because of its medical, economic, and social importance [3,4,5,6].

A pandemic was considered to be unpreventable since 2005, when the World Health Organization announced pre-pandemic period [7]. New technologies of vaccine production had been started to develop sufficient quantities of the pandemic vaccines in a short period of time [8]. In case of flu vaccine shortages each country should identify groups of population at high risk of infection.[9].

According to that epidemic situation, seasonal trivalent influenza vaccine had to be used together with A/California/07/2009 (H1N1) vaccine. Importance of influenza vaccination in the chronically ill patients was discussed as high priority.

It is well known, that influenza is dangerous in children with chronic illness, especially in diabetic-patients, they have an increased incidence of different infections as well as in the respiratory tract [15]. All infections, including influenza, are associated with significant morbidity and mortality in patients with diabetes, in part because of poor glycemic control and ketoacidosis, as well as complications.

In general diabetes triples the risk of hospitalization after influenza A (H1N1) and the odds ratio for intensive care unit admission is 4 times higher among hospitalized patients with diabetes compared to those without. Infection-related mortality in diabetic patients is reported to be in four times higher as well [16]. In 2009-2010, Influenza A virus was identified in 21% of hospitalized children with diabetes. About 13% of them were admitted to the pediatric intensive care unit. A double number of new diabetes diagnoses was registered in pandemic 2009 comparing to the pre-pandemic period [17].

The flu vaccination was demonstrated to be cost-effective or cost-saving in almost all populations [3]. But the highest economic value of influenza immunization is particular among children [3]. Based on the National Immunization Schedule recommendations annual influenza vaccination should be given for all who are ≥ 6 months of age. Nevertheless most of chronic patients, especially with autoimmune diseases, are not vaccinated against flu. The rates of influenza vaccination in children with diabetes mellitus in Russia are not established.

The aim of this research was to study influenza vaccination rates in school-aged children with diabetes mellitus during several influenza epidemic seasons.

Materials and methods.  Vaccination histories of 325 patients treated in the Nizhny Novgorod Regional Children's Clinical Hospital in 2012 were investigated. History was taken according to the medical documentation at the period of 2007 – 2012 years. Vaccination was performed with the Russian vaccine “Grippol”, “Grippol plus” or, rarely, “Influvac”. The period of 6 years was divided into 3 parts: the pre-pandemic period (2007 – 2008 yrs.), the pandemic year (2009), and the post-pandemic (since autumn of the 2010 up to the 2012). 

The first group included 125 children with type 1 diabetes mellitus (T1DM), aged 8 - 18 years (middle age 13,9±0,24 yr.). 50 patients (40%) lived in the countryside, 35 children (28%) -  in the urban area, 40 (32%) - in Nizhny Novgorod. Duration of the diabetes varied from 1 to 15 years, middle 5,6±0,27 yr. Complications were found in 68 children (54,4%), such as peripheral neuropathy, microalbuminuria as the first evidence of diabetic nephropathy, necrobiosis, retinopathy, steatohepatosis.

There were 200 patients without diabetes in the second – control group. They had myopia or dysmetabolic nephropathy or obesity or stunting or vegetative dystonia. The average age of children was 13,9±1,7 years, ranging from 7 to 18 years. 113 patients (56,5%) lived in the countryside, 51 children (25,5%) -  in the urban area, 36 (18%) - in Nizhny Novgorod.

Results. Influenza vaccination has been strongly recommended by the National Immunization Schedule since 2006. Nevertheless in 2007 year children with T1DM showed a lower percentage of rate of flu vaccination (10,3% vs 22,8%; p=0,028) in comparison with non-diabetic patients (Tab.1). In 2008 only 18,2% of children with T1DM received flu vaccine and 26,2% of patients in the control group (p=0,19).

During the pandemic season both groups showed some increase of rate of seasonal flu vaccination (21,8% in the first group and 25,6% in the second). But percentage of children vaccinated against the pandemic H1N1 was extremely low (3% and 5,2%, respectively).

In the post-pandemic period the percentage of vaccinated children with T1DM ranged from 17,3% in the 2010 to 12,9% in 2012 yrs. In the 2011 the rate of flu vaccination was the lowest (7,5% vs 21,8%; p=0,024) in comparison with the pandemic year.

Analysis of factors that influenced the rate of vaccination in the pandemic 2009 year showed that those patients in the both groups were significantly more often vaccinated, who lived in the countryside (36,1% vs 10,3%; p=0,035) in comparison with children from the urban areas.

Also, the presence of complications of diabetes was supposed to be the motivating factor that increased the rate of vaccination. So, in the 2009 year 19 of 60 patients presented with complications of T1DM had flu vaccination (31,7%), compared to 3 immunized children of 11 non-complicated diabetic-patients (7,3 %; p=0,008). It was found out, such tendency was statistically significant in 2008 too: 14 of 54 patients with complicated T1DM were vaccinated (25,9%), while only 2 of 34 patients without complications (5,9%; p=0,002) received flu vaccine.

The vaccination history showed that 20 among 28 children with T1DM had never been vaccinated against influenza (71,4%) and had no more than two complications of T1DM of diabetes. By the same time all 8 vaccinated patients had two complications (p=0,029).

Conclusions. Influenza vaccination rates in children with T1DM remain low, despite recommendations that everyone over the ages of 6 months should receive the seasonal influenza vaccine. All vaccination campaigns managed by the World Health Organization in the last decade focus on people who are at high risk of serious complications if they catch the flu, such as people with chronic illness. It is needed to supply strategies to increase the reach of influenza vaccination, to synchronize recommendations made by ambulance pediatricians, pediatricians at schools. However, special attention should be given, as we suppose, to the leading role of the endocrinologist in increasing flu vaccination rates in at-risk diabetic patients.