National's health spokesperson Shane Reti says the Government is doing the right thing by hedging its bets when it comes to a COVID-19 vaccine.
Unlike some other countries, New Zealand hasn't signed up to buy doses of any one particular potential vaccine.
Health Minister Chris Hipkins, appearing with Dr Reti on Newshub Nation on Saturday morning, said they have a number of "irons in the fire".
"We are working on two levels - one is direct relationships with those who are researching and developing the vaccines, but we are also working as part of some multilateral arrangements... other countries, including Australia, the UK, the US, to make sure that we're front of the queue when a vaccine's developed."
There are dozens of different vaccines in development around the world. Most will fail, but a few have reached the all-important third phase of their trial - tested on tens of thousands of people.
One of the most promising - a joint effort between the University of Oxford and pharmaceutical company AstraZeneca - suffered a setback this week, when a participant developed a severe neurological disorder called transverse myelitis.
"The Oxford-AstraZeneca group had a major setback that I think all the vaccine manufacturers are going to be wary about," said Dr Reti, calling it a "very serious" condition.
It's not clear yet the transverse myelitis was triggered by the vaccine, or if the patient even received it - the trial is double-blind, meaning researchers aren't meant to know who received the experimental vaccine and who got a placebo until after the trial is completed.
It's possible they developed the condition completely randomly, completely unrelated to the vaccine.
Australia has a deal to get 33.8 million doses of the Oxford-AstraZeneca vaccine, and another for 51 million doses of a vaccine being developed at the University of Queensland.
Asked if this gave Australians certainly Kiwis don't have, Dr Reti said no.
"They're not giving certainty in any way because actually they don't know that that's necessarily going to be the first vaccine to get the green light. Our public plan is to be involved in as many of these different research projects... as possible."
While some experts have said the halt will be brief and not a huge setback in the overall race for a COVID-19 vaccine - Labour MP David Parker on Friday saying he's picking June for a global rollout - Dr Reti isn't so sure.
"If I was going to guess... I'd be surprised if I saw it in 18 months actually," he said.
Hipkins said predicting when a vaccine would be ready is impossible.
"How long is a piece of string? The research takes as long as it takes... Things can be looking very promising, and then they can take a setback. We've just got to be prepared for every scenario."