All experts recommend flu vaccination for children with cystic fibrosis every year. These recommendations are associated with reduced morbidity and mortality in patients with chronic lung diseases, such as cystic fibrosis [1, 2].

According to V. Fainstein et al., When using a live influenza vaccine, there is a high probability of adhesion of many microorganisms to the pharyngeal and respiratory mucous cells [3]. These microorganisms include Staphylococcus aureus, Haemophilus influenzae and Streptococcus pneumoniae. The clinical significance of this fact has not been fully studied, but the consequence of colonization may be an increased risk of developing secondary respiratory infections caused by these microorganisms.

Most experts recommend vaccinating children with CF with two vaccines: pneumococcal polysaccharide vaccine (Pneumovax) and pneumococcal conjugate vaccine (Prevnar). Despite the fact that pneumococci are not the most common causative agents of respiratory infections in children with cystic fibrosis, these vaccines are effective and safe in all vaccinated children.

The reason for the use of the two vaccines is that, on the one hand, the pneumococcal polysaccharide vaccine contains antigens of 23 pneumococcal serotypes (Prevnar - 7 serotypes) and, on the other hand, the duration of immunological protection when using pneumococcal polysaccharide vaccines are much less numerous than lifetime protection when using the Prevnar vaccine [4]. It should be noted that this vulnerable group of patients needs the maximum possible protection against any potential respiratory pathogen.

The rare pathogens that can cause respiratory infections in children with cystic fibrosis are: S. aureus, Pseudomonas aeruginosa, Burkholderia cepacia, Mycobacterium avium and sometimes non-typable strains H. influenzae, Moraxella catarrhalis, Xanthomonas maltophilia, Alcaligenes xylosoxidans, Enterobacteriaceae family microorganisms and Aspergillus fungi. Vaccines active against these microorganisms have not yet been developed. The reason S.pneumoniae is the microorganism that most often colonizes the airways, so rarely causing disease in children with cystic fibrosis, perhaps because these patients are immune to pneumococcal vaccines.