Immunobiological cold chain performance assessment in Brazil: mixed methods research

BACKGROUND: Cold chain maintenance is essential to prevent changes in the composition, efficacy, and potency of immunobiologicals, thereby ensuring their immunogenicity. OBJECTIVE: To evaluate the performance of the immunobiological cold chain in vaccination rooms located in Primary Health Care units in Brazil. METHODS: This mixed-methods study employed a sequential explanatory design (QUAN→qual) and was conducted in vaccination rooms across different regions of Brazil between 2021 and 2022. States, municipalities, and vaccination rooms were selected using multistage probabilistic sampling. In the quantitative phase, an analytical cross-sectional study was conducted using the Immunobiological Agent Conservation Assessment Scale, applied to nursing professionals, along with the collection of municipal-level indicators. Logistic regression was used to identify factors associated with adequate cold chain performance. In the qualitative phase, a descriptive-exploratory study was conducted with state, regional, and municipal managers, as well as nursing professionals. Data were collected through individual semi-structured interviews and analyzed using thematic content analysis. Integration of quantitative and qualitative data was performed through a connecting approach, including the development of joint displays and meta-inferences. RESULTS: Cold chain performance at the national level was classified as inadequate. DTPw-HB/Hib vaccination coverage (OR: 1.029; 95% CI: 1.007-1.052) and urban location (OR: 1.034; 95% CI: 1.013-1.055) were identified as factors associated with adequate performance. Qualitative findings revealed structural, logistical, and organizational challenges, including regional inequalities, transportation difficulties, infrastructure limitations, and financial constraints, which influence cold chain performance. CONCLUSIONS: The performance of the immunobiological cold chain in Brazil was classified as inadequate and was associated with geographic factors, such as the country's large territorial extension and climatic diversity, which primarily affect the transportation of immunobiologicals, as well as limitations in physical infrastructure, regional financial inequalities, and weaknesses in municipal-level management.