A warning Pfizer's Covid-19 vaccine isn't a shoo-in for New Zealand.

MedSafe is today reviewing clinical trial data and information from international roll-outs.

Provisional approval for immunisations could be granted tomorrow for when doses arrive.

But Malaghan Institute Director Professor Graham Le Gros told Heather du Plessis-Allan it's not a formality.

"They are our guardians and are required to look at if its right for New Zealand's population.

"And there may be some differences that they are aware of or are concerned about."

Our approval comes as the European Union has adopted a set of measures to control vaccine movement until the end of march.

It means European-based pharmaceutical companies must seek authorisation before they export doses.

Le Gros when we're good to people - we expect it to go the other way.

"I think given the desperation over in the EU - some places are really in a dire situation - you could imagine there is tremendous political or social forces for them to get the vaccine first."

LISTEN ABOVE