There's already an array of vaccines in the pipeline - which ones will New Zealand get?
Probably a few - all going to plan.
The government wants a "portfolio" of vaccines and says it's making deals with a lot of companies.
That hedges our bets that at least some of the candidates New Zealand is backing will go all the way and produce a viable vaccine.
If more than one does, it means there are likely to be more doses available to distribute.
It also means New Zealanders will probably be vaccinated with a range of products.
Different vaccines, depending on their properties, could be tailored to different groups so, for example, one-jab products might be used for remote populations.
Which companies is the government going with?
So far two have been announced - Pfizer and Janssen.
Pzifer's product could be in the country as early as March and is a two-dose vaccine that would cover 750,000 people.
Janssen's requires just one injection but would not get here until closer to September, with two million initial doses and more to follow if needed.
The government says there will be more announcements to come.
Who's first in line for a jab - and when are the rest of us?
The government is looking at different scenarios, like whether there is community transmission here when a vaccine is ready, but it hasn't revealed details yet.
It's weighing up those most at risk of contracting the disease, most at risk of spreading the disease, and most at risk of serious illness or death.
That means border workers, frontline health staff, essential workers, older New Zealanders and those in other vulnerable groups are likely to be first in line.
Will I have to get one?
No. Vaccination will not be compulsory.
Director-General of Health Ashley Bloomfield says for it to have a good effect across the population at least 80 percent would need to be immunised - but 95 percent would be ideal.
Those who are not vaccinated may face restrictions though - for example Qantas is saying no one will be able to fly with it internationally without proof they've been immunised.
How likely is it these vaccines will pass the final hurdles?
There's no guarantee but experts are optimistic, saying by the time most vaccines get to phase three (final, large) trials they have already passed many other hurdles.
But, the lack of publicly available data does make it hard to assess exactly how good each one is looking - and what the pitfalls might be.
Any vaccine will need Medsafe approval to be used in New Zealand and work is already under way to fast-track that, with Medsafe reviewing data and information from the drug companies as it becomes available instead of waiting for it to be collated in a final application.
Regulators from similar countries are sharing information to avoid duplicating work.
However, if countries like the United States or Britain approve a vaccine for emergency use before Christmas, as they are considering, it doesn't mean New Zealand will too. Emergency use is different to product approval.
Medsafe says it will not be letting anything through that does not meet its usual standards.
How do the vaccines work?
The two New Zealand is in line for so far are based on different technology.
The Pfizer one uses Covid-19's genetic material while the Janssen one is based on a type of cold virus that is very similar to Covid but harmless.
Each one would cause the body to produce antigens - a sort of antibody generator, in this case against Covid-19.
Those protective antibodies are one of our lines of defence against viruses.
Just because a vaccine protects an individual from getting sick, it doesn't mean it will stop them spreading the disease, which has big implications for protecting whole populations.
Experts say that may not be really known until there has been a large roll-out.
How long will the vaccines last?
That is one of the big unanswered questions.
Scientists don't know whether the vaccine will give long-term immunity, like the measles jabs or whether it will require top-ups, or even regularly tweaked vaccines, like for flu strains.
That will be one of the big priorities for study as the vaccines are distributed in large numbers around the world.
What else is being done to get the country ready?
There is a lot of paraphernalia needed for a mass vaccination campaign so the government is on a shopping spree.
It's bought nine large super-cold (-70 C) freezers to store the Pzifer vaccine and is getting 40 smaller ones so it can be stored in different places when it is rolled out.
The Janssen one only needs ordinary refrigeration.
It's also buying personal protective equipment (eg masks, gloves, gowns), needles, syringes, saline ampoules, gauze swabs, cotton balls, tape, dry ice, sharps containers and biobags.
And work is continuing on the logistics to vaccinate an entire population. That could be a big challenge, especially getting enough workers in an already stretched health workforce to get the job done while carrying on with other care.
