ACTIVE IMMUNIZATION - A SAFE METHOD FOR PREVENTING TYPICAL INFECTIONS AND SEVERE FORMS CAUSED BY HAEMOPHILUS INFLUENZAE

Abstract

Objectives. To compare trends in Haemophilus influenzae infections and the impact of immunization internationally and in the Republic of Moldova, with a detailed analysis of incidence and vaccination coverage in the pediatric population during 2021–2025.

Methods. A retrospective descriptive epidemiological study was performed using secondary data analysis and a narrative synthesis of the literature. Reports from the World Health Organization and the European Centre for Disease Prevention and Control, together with relevant literature from 2000–2025, were reviewed for the international context. Data for the Republic of Moldova for 2021–2025 were obtained from statistical yearbooks of the National Agency for Public Health and the National Bureau of Statistics. The analysis included microbiologically confirmed cases, incidence in the pediatric population, and vaccination coverage among one-year-old children.

Results. The introduction of conjugate vaccines against Haemophilus influenzae type b reduced the incidence of invasive disease by 90–99% in countries with established immunization programs. In the Republic of Moldova, 213 microbiologically confirmed severe cases were reported during 2021–2025. Incidence was 1.07 per 100,000 children in 2021, increased to 2.05 per 100,000 in 2023, and reached 1.89 per 100,000 in 2025. Vaccination coverage among one-year-old children decreased from 87.2% in 2021 and 2022 to 87.3% in 2023, 86.5% in 2024, and 83.6% in 2025.

Conclusions. Conjugate immunization remains the principal measure for preventing invasive Haemophilus influenzae type b infections. Vaccination coverage below the recommended level and the circulation of non-b and nontypeable strains support the need to strengthen immunization, continuously monitor cases, and expand microbiological and molecular surveillance.