Saidu Yauba, Sobngwi Joelle, Nkwain Jude, Biloa O. Tracy, Kobela Marie, Nsangou Charles, Ename E Hermelle, Vouking Marius, Sama Julius, Biloa Alain, Nimpa M Marcellin, Adan Baku, Mbollo Marianne, Brison Mike, Kamga Delphine, Mbu Robinson and Nzuobontane Divine
Background and objective: Vaccination has been hailed as one of the most cost-effective public health intervention in modern medical history. For this intervention to be effective, vaccines must be stored and transported within the recommended temperatures ranges of 2°C to 8°C. However, few studies have investigated compliance to this recommendation. This study was designed to evaluate vaccine exposure to temperatures outside the recommended range during storage and transport within Cameroon’s cold chain system.
Methods: Forty-eight shipment boxes were prepared and placed at the National Vaccine Store on October 24, 2015. Each shipment contained ten vials of Diphtheria-Tetanus and Pertussis containing vaccines, a monitoring form and a datalogger. The dataloggers were programmed to continuously record temperatures as shipments moved from the National Vaccine Store to 48 target health facilities.
Results: Regarding freeze exposure, 83% of shipments were exposed to freezing at one point during the study. During storage, freeze exposures were highest at the facility level (51%), followed by the district level (31%). The minimum temperatures reached ranged from -0.5°C to -23.8°C. Unlike freezing, all shipments were exposed to temperatures above 8°C at one point. 96% of shipments were exposure above 8°C for over 10 h. During storage, heat exposures were highest at facility level, followed by district level. Transport was a major contributor to both heat and freeze exposures. The heavy use of outdated and uncertified cold chain equipment and gaps in healthcare worker knowledge, attitudes and practices were important contributors to inadvertent exposures.
Conclusion: The findings suggest that the exposure of vaccines to temperatures outside the recommended range is a widespread problem in Cameroon. This problem requires urgent attention as it represents a real risk to the effectiveness of the immunization program.