How the use of vaccines outside the cold chain or in controlled temperature chain contributes to improving immunization coverage in low- and middle-income countries (LMICs): A scoping review of the literature.

Background: Most vaccines are recommended for storage at temperatures of +2°C to +8°C to maintain potency. Immunization supply chain bottlenecks constraints reaching populations with life-saving vaccines. The World Health Organization permits the use of vaccines outside the cold chain as "controlled temperature chain (CTC)" upon meeting certain conditions and has set targets to license more vaccines CTC by 2020.