Using Shewhart charts to monitor quality characteristics of preventive vaccines for tuberculosis

Abstract

Scientific relevance. The quality of medicinal products, particularly vaccines, is contingent on the stability of the manufacturing process at all stages, which can be evaluated using Shewhart charts for data obtained by monitoring the quality attributes of interest.Aim. This study evaluated the stability of the quality and manufacturing processes of the BCG and BCG-M tuberculosis vaccines using Shewhart charts.Materials and methods. This study focused on samples of the BCG tuberculosis vaccine and the BCG-M tuberculosis vaccine, a less reactogenic alternative for primary immunisation. Both vaccines were released to the market in 2019–2022. The quality of samples was assessed for stability based on their potency and total bacterial count, which are the key parameters for immunogenicity evaluation. These quality parameters were compared using test results submitted by the manufacturer and obtained at the testing centre. The authors plotted individuals charts (X-charts) and moving range charts (R-charts) in accordance with national standards GOST R 50779.42-99 and GOST R ISO 7870-2-2015.Results. The quality of the BCG and BCG-M vaccines remained stable during the entire follow-up period (2019–2022). For some periods, the retrospective analysis of R- and X-charts revealed characteristic trends meeting special cause criteria. The Pearson correlation coefficient (r) between the data submitted by the manufacturer and the data obtained at the testing centre ranged from 0.2 to 0.8.Conclusions. The Shewhart charts demonstrated that the quality parameters of the BCG and BCG-M tuberculosis vaccines tested in 2019–2022 were stable. These vaccines had stable manufacturing processes, as shown by the R- and X-charts. However, the warning signs indicated that additional measures should be taken to standardise the manufacturing processes. The findings suggest that Shewhart charts may be recommended for monitoring the production and quality of tuberculosis vaccines.