Expanded Vaccination Option Against Pneumococci Thanks to 15valent Vaccine
Our arsenal for preventing pneumococcal diseases has been expanded with a 15-valent conjugate vaccine that includes important serotypes causing invasive pneumococcal diseases (IPD). The following text briefly summarizes basic information not only about IPD, their prevention, diagnosis, and treatment, but especially about the management of vaccination with the 15-valent vaccine in practice.
Etiopathogenesis of IPD
Pneumococci are bacteria that often cause infections primarily of the respiratory tract but can also lead to serious infections outside the respiratory system. Diplococcus pneumoniae is a gram-positive diplococcus, of which we know over 100 serotypes. About 20 of these are potential causes of more than 80% of IPD, with 13 causing at least 70% of IPD in children.
Pneumococcal infection can affect people of any age; however, the most vulnerable groups are young children and the elderly. For children under 1 year, it is a particularly dangerous and sometimes life-threatening infection. The severity of clinical courses ranges from relatively mild forms of pneumococcal infections, such as sinusitis, otitis, and bronchitis, to bacteremic or non-bacteremic pneumonias, and up to purulent meningitis or rarer osteomyelitis and endocarditis. Significantly at risk are individuals with compromised immunity, especially those with non-functioning or defective spleen function.
The entry point for pneumococcal infection is the respiratory tract. After infection, clinical disease may not always occur, but both children and adults can become carriers of pneumococci. In adults, carriers are found in up to 20% of cases, and in children, even up to 40 (60)%. These carriers then serve as infection sources for their surroundings, either in families or children's groups.
Diagnostics of IPD and treatment possibilities and limitations
In laboratory diagnostics, alongside basic tests (complete blood count and C-reactive protein), additional methods are used, such as culture testing of ear material during paracentesis or spontaneous tympanic membrane perforation, blood culture, and sputum examination, or material from bronchoalveolar lavage. Throat, nasal, or ear swabs without secretion do not contribute to diagnostics. In terms of pneumococcal antigen in urine, it is a supportive indicator but not a definitive diagnostic criterion as it can be positive even in mere carriers of pneumococci.
Pneumococci are bacteria sensitive to many antibiotics; however, given the potentially severe courses, especially in the extremes of age and in immunosuppressed individuals, vaccination is unequivocally recommended starting from infancy.
Available vaccines
Until recently, two conjugate pneumococcal vaccines for infants were available on the market: Synflorix (PCV10 – 10-valent pneumococcal conjugate vaccine) and Prevenar13 (PCV13 – 13-valent pneumococcal conjugate vaccine). The portfolio of these vaccines has been expanded with the Vaxneuvance vaccine (PCV15 – 15-valent pneumococcal conjugate vaccine), which was approved by the European Medicines Agency (EMA) from December 2021 for adults and from October 2022 for children from 6 weeks of age.
In November 2022, the Czech Vaccinology Society CLS JEP issued a statement on the use of conjugate pneumococcal vaccines for children, recommending the preferential use of more-valent vaccines.
Characteristics of the 15-valent vaccine and findings from clinical research
Vaxneuvance is a 15-valent conjugate vaccine that includes the most important serotypes causing IPD: 1, 3, 4, 5, 6A, 6B, 7F, 9V, 14, 18C, 19A, 19F, 22F, 23F, 33F.
In extensive clinical research, it was administered to several thousand children, including high-risk groups. Studies have confirmed its non-inferiority to the 13-valent vaccine and superiority for the 22F and 33F strains, which the 13-valent vaccine does not include. Superiority was also confirmed in the study (protocol 029) for serotype 3, a common cause of IPD in children and adults, which has a high invasive potential and is associated with more frequent complicated pneumonias and a higher risk of death.
Administration schedule, combination possibilities, and switch
The vaccine is administered in a 3-dose schedule for full-term immunocompetent infants and children aged 6 weeks to < 2 years: 1st dose from 6 weeks of age, 2nd dose 8 weeks after the first dose, 3rd dose at 11-15 months of age.
Robust studies have verified the immunogenicity of the vaccine when given to preterm infants, with a very good immune response observed. The vaccination schedule for these children is recommended in a 4-dose regimen (3-dose primary series followed by a booster), with the 1st dose given at 6 weeks of age, with 4 to 8-week intervals between primary series doses. The fourth (booster) dose is given between 11-15 months of age and at least 2 months after the 3rd dose.
The vaccine can be routinely combined with other vaccines given as part of the vaccination schedule. Concerning the switch from PCV 10/13 to PCV 15, it can be done at any time within the vaccination schedule. Re-vaccination of children previously completely vaccinated against pneumococci is not recommended.
Adult vaccination
Vaxneuvance is also indicated for adults aged 18 years and older. In the study (protocol 019), non-inferiority was proven compared to the 13-valent vaccine for the 13 common serotypes and superiority for the two additional serotypes 22F and 33F, and for the common serotype 3 (in adults over 50 years of age and previously unvaccinated with pneumococcal vaccine).
MUDr. Hana Roháčová, Ph.D.
Infectious Diseases Clinic, Bulovka Hospital
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