A Bill making a technical change to the Medicines Act to ensure the vaccine rollout can continue legally has passed under urgency at Parliament.
It comes after a High Court decision found it was "reasonably arguable" the Government's approval of the Pfizer vaccine went beyond what the Act allowed.
Associate Health Minister Ayesha Verrall said the Bill removed a section of the Act which only gave the Minister of Health the right to approve medicines to a limited number of people.
"The Medicines Act is an outdated piece of legislation that has not kept pace with international regulatory practice.
"Responding to the COVID-19 pandemic has highlighted an urgent need for amendments to the Medicines Act."
Dr Verrall said the changes would also affect other situations where there was a need for timely access to safe and effective medicines.
Six products are potentially affected by the Court decision, including the Pfizer vaccine, two flu vaccines, two types of contraceptives, and an electrolyte solution.
Prior to the amendment, Health Minister Andrew Little said the legislation had been used for decades by successive Governments to grant early access to substances when it was in the public good
"The law has, for some time now, lacked clarity over how it can be applied."