The 13-valent pneumococcal conjugate vaccine is an effective tool for the prevention of invasive pneumococcal infections and pneumonia in children, but the efficacy of vaccination has not yet been studied in adult patients aged 65 years and more. However, it is in this age group that there is an urgent need to prevent pneumococcal infections, including community-acquired pneumococcal pneumonia.

The results of the first large-scale prospective study on the efficacy of the 13-valent pneumococcal conjugate vaccine in elderly patients (community pneumonia immunization trial in adults - CAPiTA) were presented at the 16th International Congress on infectious diseases.

The CAPiTA study is one of the largest vaccine prevention studies in adult patients - 84,496 adult patients over the age of 65 who received PCV-13 or a placebo participated in the study. The study did not include residents of nursing homes and long-term care facilities, patients who had previously been vaccinated with pneumococcal vaccines, and people who were immunocompromised.

The main objective of the CAPiTA study was to prevent the first episode of community-acquired pneumonia caused by the pneumococcal serotype included in the vaccine. Secondary objectives included prevention of the first episode of non-bacterial / non-invasive community-acquired pneumonia and other invasive pneumococcal infections caused by the pneumococcal serotypes included in the vaccine.

Pneumococcal pneumonia and invasive pneumococcal disease were confirmed in 58 hospitals participating in the study.

To identify episodes of community-acquired pneumonia caused by pneumococcal serotypes that are part of the vaccine, we used a special serotype-specific test for pneumococcal antigenuria in urine, developed by Pfizer specifically for this study. This allowed the researchers to determine the vaccine serotypes of pneumococcus with a high degree of probability in the urine of patients who developed community-acquired pneumonia.

The efficacy of PCV-13 was 45.5% in preventing the first episode of community-acquired pneumonia caused by the pneumococcal serotype included in the vaccine compared to placebo. In addition, 45% were the effectiveness of PCV-13 in preventing the first episode of non-bacterial / non-invasive community-acquired pneumonia and 75% in preventing other invasive pneumococcal infections caused by pneumococcal serotypes that are part of the vaccine. This is analysis data in accordance with the study protocol. When performing a modified analysis according to the prescribed intervention (ITT analysis), the effectiveness of vaccination was slightly lower - 37.7%, 41% and 75.7%, respectively.

The incidence of serious adverse events, as well as the mortality rate, were comparable in the two groups. As expected, in patients who received the vaccine, local reactions in the form of redness, pain and swelling at the injection site were significantly more frequent, however, the frequency of severe local reactions was very low and comparable between the 2 groups.

The incidence of invasive pneumococcal infections in the United States in patients 65 years of age and older decreased by 90% after the introduction of the 7-valent pneumococcal conjugate vaccine in the pediatric population.

Compared to PCV-7, PCV-13 has 3 key serotypes - 1, 3 and 7F. These serotypes rarely colonize children; therefore, the authors are not sure that immunizing children with PCV-13 will significantly reduce the transmission of these 3 serotypes in the general population.

A 23-valent pneumococcal polysaccharide vaccine (PPV23) is available to prevent infection in the elderly, which, according to the Cochrane systematic review, prevents about a quarter of all invasive pneumococcal infections in the elderly (Cochrane Database Syst Rev. 2013; 1: CD000422) At the same time, most pneumococcal infections are only non-bacterial forms of community-acquired pneumonia. Invasive pneumococcal infections are relatively rare - 0.5% of all pneumococcal infections. The PPV23 vaccine has not shown efficacy in preventing pneumonia in the elderly, and there is therefore an urgent need for an effective vaccine in this particular category of patients.