Two studies in BMJ yesterday highlight operational challenges of the global COVID-19 vaccination program, including difficulties meeting demand and ensuring fair and equitable access in low- and middle-income countries (LMICs).The first study warned that nearly a quarter of the world's population may not have access to a COVID-19 vaccine until at least 2022, and the second study estimated that only two thirds of adults worldwide are willing to accept a COVID-19 vaccine.One-fourth may be left out in 2021For the first study, researchers from Johns Hopkins Bloomberg School of Public Health analyzed pre-orders for COVID-19 vaccine, finding that a total of 7.48 billion doses (3.76 billion courses for a two-dose vaccine) from 13 manufacturers