Some front line workers, such as police and teachers, have been calling for prioritization for shots on the basis of their jobs.

But chair for the Joint Committee on Vaccination and Immunization Professor Weixin Lim said the current system was the best way to keep up the pace of immunizations.

Of all the different approaches to vaccination, getting vaccines into arms as quickly as possible is the fastest way and the best way to maximize benefit to the population.

Taking all of these factors into account, we advise that the offer of vaccination in phase two should still be aged based starting of the oldest and proceeding in the following order those age 40 to 49 followed by those aged 30 to 39 and lastly those age 18 to 29.

An occupation based vaccine program has never been tested before on a large scale in the UK it is in that sense, untested and untried, so trying to switch from an age based program to an occupation based program will be more complex and potentially introduce more delays to the program.

Britain, whose rollouts has been among the fastest in the world, aims to complete phase one of its vaccine program by mid April.