Epidemiological investigation of hepatitis C virus infections among children in oncohematology departments

The aim of this study was to conduct an epidemiological analysis of hepatitis C infection in children with oncohematological diseases (OHD) using phylogenetic analysis of HCV nucleotide sequences and to analyze the causes and factors of HCV nosocomial transmission.
Materials and methods. A retrospective analysis of HCV genetic isolates obtained from children with oncohematological diseases treated at the «Dmitry Rogachev National Medical Research Center of Pediatric Hematology, Oncology and Immunology» (the Center) was conducted. The analysis included all children with HCV markers (anti-HCV and/or HCV RNA) identified between 2013 and 2025 during hospitalization and treatment at the Center—a total of 146 children. The children's ages ranged from 0 to 18 years, and from September 1, 2022, to 21 years. Samples were taken from the Center's bacteriology laboratory collection. Genotyping and phylogenetic analysis were performed at the Central Research Institute of Epidemiology of Rospotrebnadzor for 30 patient blood samples containing HCV RNA in quantities sufficient for analysis (at least 1000 IU/mL). 
To compare the distribution of HCV genotypes, the VGARus database data from 997 individuals was used. The core/E1 region of the HCV genome was sequenced and a phylogenetic analysis was performed. A Bayesian approach was used with the BEAST2 software package. The tree was visualized using FigTree.
Results. In the structure of HCV genotypes isolated from children in the oncohematology departments, genotype 3a was predominant (77%), while 1b accounted for 23%. In contrast to the general population, where genotypes 3a and 1b circulate with equal frequency, the prevalence of genotype 3a among children with OHD indicates a greater involvement of this genotype in cases of nosocomial infection. Phylogenetic analysis revealed three common HCV clusters: 14 children with genotype 3a (13 children from the Amur Region and 1 child from the Altai Krai) and two common clusters with genotype 1b (2 patients each from the Kyrgyz Republic and Uzbekistan). The majority of HCV infection cases in children with OHD (60%) were nosocomial in origin. Cases of HCV infection in children from the Amur Region are associated with a long-standing chronic HCV epidemic in the oncohematology department of the Amur Regional Children's Clinical Hospital. No cases of infection have been identified at the Center. A patient from the Altai Krai region may have been infected at the Center in 2013-2014 during blood collection from a central venous catheter (CVC) due to improper hand sanitization, glove changing, aseptic technique, or work surface zoning. Standardization of procedures, implementation of aseptic non-touch technique (ANTT), training, and monitoring of staff knowledge and skills, widely implemented in the Center's work, have demonstrated high effectiveness, resulting in the absence of HCV transmission cases for over 10 years.
Conclusion. Nosocomial HCV transmission in the OHD departments requires the widespread implementation of modern approaches to preventive and anti-epidemic measures, such as aseptic non-touch technique (ANTT), standardization of procedures, staff training, and knowledge and skills audits.