RESUMO
Preventing vaccine freezing is one of the biggest challenges in vaccine management. Until 2018, vaccine carriers used in the immunization program lacked features to prevent vaccine freezing. Freeze-preventive vaccine carriers (FPVCs) have an engineered liner that buffers vaccines from direct exposure to frozen ice packs. A field evaluation of three FPVCs was conducted in 24 health posts in eastern Nepal. The objective was to evaluate the FPVCs' performance, acceptability, systems fit, and cost, to inform prequalification and introduction planning. The study was carried out in two phases: in the first phase, FPVCs containing dummy vaccines (labeled "Not for Human Use") were transported to outreach sessions along with a standard vaccine carrier (SVC); in the second phase, the FPVCs were used for transporting vaccines taken to outreach sessions and used for vaccinating eligible children. The study gathered quantitative and qualitative data from health workers, logbooks, and electronic temperature monitors placed inside and outside the FPVCs. Results indicate the FPVCs successfully prevented temperatures below 0 °C more than 99% of the time-except at one site, where ambient temperatures were below the minimum rated testing temperature specified by the World Health Organization. Internal cool-down times for the FPVCs were highly variable, as were mean kinetic temperatures, possibly driven by the wide range of ambient temperatures and higher-than-expected variations in freezer performance, which, along with the need to transport ice packs to some locations, affected ice-pack temperatures. Almost all health workers requested smaller, lighter-weight FPVCs but appreciated the FPVCs' ability to prevent vaccines from freezing while avoiding undue heat exposure. FPVCs had benefit-cost ratios greater than 1 and hence good value for money. Results point to the importance of understanding the intended environment of use and the need for smaller, short-range as well as long-range carriers.
RESUMO
BACKGROUND: Surveillance for adverse events following immunization (AEFI) is important to monitor vaccine safety and should lead to appropriate responses to improve health and immunization program. Bleeding following vaccination is not recognized as an important AEFI. Without policy of vitamin K (VK) prophylaxis at birth, vitamin K deficiency bleeding (VKDB) could be an important cause of bleeding in young infants and may manifest as AEFI. METHODS: We retrospectively analysed all serious AEFI cases that presented with external or internal bleeding reported to Nepal's AEFI surveillance system during 2016-2018. The cases were classified as VKDB, suspected VKDB or non-VKDB. RESULTS: During the period, 16 serious AEFI with symptom or sign of bleeding were reported representing 21.3% of all serious AEFI reported. Cases were between 40 and 94 days of age. The National AEFI Investigation Committee classified all cases as coincidental. Fourteen cases (87.5%) had bleeding from injection site. Median time from vaccination to injection site bleeding was 4.3 h (interquartile range: 2.1-11.6 h). Six cases (37.5%) had intra-cranial haemorrhage. Only one case had confirmed history of receiving VK at birth. Ten cases (62.5%) received appropriate treatment (VK injection; blood transfusion if needed). Based on limited laboratory investigations available, three cases (18.75%) could be classified as late onset VKDB and 11 cases (68.75%) as suspected late onset VKDB. CONCLUSION: VKDB should be suspected in young infants presenting with bleeding including following vaccination, and prompt treatment should be initiated. Bleeding following vaccination should be recognized as an important AEFI as even a small amount of blood loss in young infants can be catastrophic. We posit that this series is a small subset of VKDB cases in Nepal detected through AEFI surveillance system. In countries without policy of VK prophylaxis at birth including Nepal, the policy should be introduced.
