Influenza immunization for children with bronchopulmonary dysplasia in Poland

Effectiveness and safety of seasonal influenza vaccination in children with underlying respiratory diseases and allergy

Influenza causes acute respiratory infections and various complications. Children in the high-risk group have higher complication and hospitalization rates than high-risk elderly individuals. Influenza prevention in children is important, as they can be a source infection spread in their communities. Influenza vaccination is strongly recommended for high-risk children with chronic underlying circulatory and respiratory disease, immature infants, and children receiving long-term immunosuppressant treatment or aspirin. However, vaccination rates in these children are low because of concerns regarding the exacerbation of underlying diseases and vaccine efficacy. To address these concerns, many clinical studies on children with underlying respiratory diseases have been conducted since the 1970s. Most of these reported no differences in immunogenicity or adverse reactions between healthy children and those with underlying respiratory diseases and no adverse effects of the influenza vaccine on the disease course. Further to these studies, the inactivated split-virus influenza vaccine is recommended for children with underlying respiratory disease, in many countries. However, the live-attenuated influenza vaccine (LAIV) is not recommended for children younger than 5 years with asthma or recurrent wheezing. Influenza vaccination is contraindicated in patients with severe allergies to egg, chicken, or feathers, because egg-cultivated influenza vaccines may contain ovalbumin. There has been no recent report of serious adverse events after influenza vaccination in children with egg allergy. However, many experts recommend the trivalent influenza vaccine for patients with severe egg allergy, with close observation for 30 minutes after vaccination. LAIV is still not recommended for patients with asthma or egg allergy.

Influenza diagnosis and vaccination in Poland

In Poland between several thousand and several million cases of influenza and suspected influenza cases are registered, depending on the epidemic season. A variety of methods are available for the detection of the influenza viruses responsible for respiratory infection starting with the isolation of the virus in chick embryos or in cell lines such as MDCK, VERO, etc., and finishing with a variety of modifications of the classical PCR molecular biology such as PCR multiplex and Real-Time. The most effective way to combat influenza is through vaccination. Regular vaccination is one of the few steps that may be taken to protect individuals, especially in high-risk groups, from the potential and serious complications of influenza. In many countries, including Poland, despite the recommendations, the rate of vaccination against influenza is still low in all age groups. In the epidemic season 2011/2012, the level of distribution of the seasonal influenza vaccines was 4.5% of the population.

Inactivated Influenza Virus Vaccines in Children

Healthy children aged < or =2 years have hospitalization rates during influenza periods 12 times those of older children and comparable to rates in the elderly population. In 2003, killed influenza vaccines were "recommended" for children with high-risk conditions and were "encouraged" for children aged 6-23 months. Studies involving several thousand children show that split-virus vaccines are safe and immunogenic in healthy children aged > or =6 months and in high-risk children. In children aged < or =9 years, 2 doses of vaccine are required initially to achieve maximum protection. Studies of children aged 6 months to 15 years show vaccine efficacies of 31%-91% against influenza A and 45% against influenza B. Among children attending day care, a reduction in the rate of acute otitis media of 32%-36% was demonstrated. Studies suggest that use of killed vaccines among children is cost-saving. In conclusion, the data show that killed influenza vaccines in children are safe, immunogenic, effective, and potentially cost-saving.

Safety and immunogenicity of a paediatric presentation of an influenza vaccine

BACKGROUND

Flu vaccination in otherwise healthy infants and young children is important to prevent severe disease, as well as to control epidemic spread of influenza infection.

AIMS

To examine the safety and immunogenicity of a paediatric presentation of a purified, inactivated, triton split influenza vaccine.

METHODS

Two doses of the vaccine, provided in prefilled syringes of 0.25 ml, were administered, one month apart, to 67 children under 3 years of age.

RESULTS

Nine cases of immediate reaction to vaccination (macules/papules) were observed after the second injection only. During the study period, 9% of children experienced at least one delayed local reaction, and 28% of children presented at least one systemic reaction. Almost all reactions were mild and transient. Immunogenicity results surpassed the European Community recommendations for a 0.50 ml dose of vaccine in adults.

CONCLUSION

This paediatric formulation of inactivated flu vaccine appears safe and immunogenic in children from 6 months to 3 years of age; the convenient presentation in a prefilled syringe of 0.25 ml volume will facilitate administration of the dose recommended for young children.

Antibody response to influenza immunization in two consecutive epidemic seasons in patients with renal diseases

The aim of this study was to assess antihemagglutinin and antineuraminidase antibody kinetics in 26 patients with renal diseases vaccinated against influenza in two consecutive epidemic seasons. Antibody responses were measured before immunization and 1, 3 and 6 months after immunization. Antihemagglutinin (HI) antibodies were determined by the hemagglutinin inhibition test and antineuraminidase (NI) antibody levels by the neuraminidase inhibition test. After vaccination HI and NI antibody titers significantly increased when compared with the pre-vaccination levels. Three months after vaccination the protection rates ranged from 50 to 61.5% in the 1995/96 season and 100% for all antigens in the 1996/97 season. Response rates ranged from 50 to 57.7% and 93.8 to 100% respectively. Significantly higher humoral response was recorded in the 1996/97 season than in the 1995/96 season. No serious adverse reactions were observed in the vaccinated patients and no symptoms of influenza or influenza-like infection were noted. In spite of some doubts about the safety and efficacy of influenza vaccination in patients from high-risk groups, the results of this study showed that many of them are able to produce HI antibodies in titers which are sufficient to protect against the influenza infection.

The epidemiology and history of influenza

Disease caused by influenza virus has been known from ancient times. However, in spite of the progress in pharmacology and vaccinology, this pathogen still affects morbidity and mortality in all age groups all over the world. This article gives some essential information on the history of influenza, its pandemics and main features of influenza viruses. Data on the epidemiologic situation of influenza in Poland in the period 1946-1999 are presented. Influenza surveillance issues and particularly prevention of influenza by vaccinations are discussed.

Immunogenicity of influenza vaccine in patients with hemato-oncological disorders

The aim of this study was to measure the production of antihemagglutinin and antineuraminidase antibodies in patients with proliferative diseases of the hematopoietic or lymphatic system, immunized with influenza vaccine in the epidemic season 1995/96. Twenty patients between 22 and 84 years volunteered for vaccination and were vaccinated subcutaneously with a single dose of split trivalent influenza vaccine ("Fluarix", SmithKline Beecham) in autumn 1995 at the outpatients clinic, General Hospital, Toruń, Poland, where they were being treated with anti-cancer chemotherapy. The vaccine consisted of a 0.5 ml dose containing 15 microg hemagglutinin (HA) of each of the following strains: A/Singapore/6/86 (H1N1), A/Johannesburg/33/94 (H3N2) and B/Beijing/184/93. Neuraminidase activity amounted to 17.24x10(-3) U/ml. Antibody production was determined in sera collected before vaccination, 10 days and 28 days after vaccination by the hemagglutinin inhibition test (HI) and neuraminidase inhibition test (NI). Mean fold increase values after vaccination were statistically significant in patients undergoing cytostatic treatment. After 28 days mean fold increase of antihemagglutinin antibodies ranged from 7.9 to 25.2, while in the case of antineuraminidase antibodies these values were between 12.4 and 14.3. It is notable that no adverse reactions were observed after immunization and none of the patients was infected with influenza virus, in spite of the fact that there was a local epidemic in the Toruń region when the study was carried out. The results presented in this paper confirm the beneficial effect of influenza vaccination in high-risk groups of patients with proliferative diseases of the hematopoietic and lymphatic systems.