Professor Allen Cheng admits he agonised over what has been dubbed the billion-dollar-a-week decision: the decision to put Melbourne under strict lockdown last year.

But he says he only wishes he’d called it sooner.

The Melbourne infectious diseases physician has just finsihed his 12-month secondment as Victoria’s deputy chief health officer.

When he started the job, on 23 July, he was probably best known in medical circles as the co-chair of ATAGI.