Robust data infrastructure will be needed for local authorities to identify eligible individuals by priority group, send invitations, arrange transport for older patients and patients with disabilities, and recall individuals to receive the second doses of some vaccines. Several of the leading vaccine candidates require ultra-cold chains and have short shelf-lives once they are removed from storage. The mRNA vaccine by BioNTech and Pfizer, for instance, must be administered within 5 days of leaving ultra-low temperature conditions (-70C);55 similar, if less extreme, requirements apply to Moderna's mRNA vaccine. Strong coordination will be needed between workers at central depots and local vaccinators to ensure the timely and efficient distribution of mRNA vaccine batches to areas without freezers. Many low-income and middle-income countries will face barriers in delivering vaccination programmes to their entire adult populations, ensuring completion of two-dose vaccination schedules, and maintaining cold or ultra-cold supply chains. As of 2018, 74 of 194 WHO member states had no adult vaccination programme for any disease; fewer than 11% of countries in Africa and South Asia reported having any such programme.56 These countries might lack immunisation registries for adults and the storage, delivery, and waste management systems needed to administer vaccines at this scale.56 It is worth noting that Gavi and its partners established ultra-cold supply chains in several sub-Saharan African countries after the 2013-14 Ebola epidemic to deploy an Ebola vaccine developed by Merck