Boris Johnson speaking at a Downing Street press briefing

The press conference discusses the progress of the COVID-19 vaccine, particularly the Pfizer-BioNTech vaccine, which has shown 90% effectiveness in trials. The UK government has ordered 40 million doses, enough for a third of the population, and plans a nationwide distribution program pending safety approvals. The order of vaccination will follow expert recommendations.

What factors will be considered when deciding the order of vaccine distribution?

What is the role of the Joint Committee on Vaccination and Immunization as mentioned in the text?