A vaccine being developed by Oxford University and the pharma giant AstraZeneca is considered a front-runner in the race to protect the world from Covid-19 infection.

There’s no guarantee this vaccine (or any other) will work. If it does it will be a massive good news story for British science and the UK government, who have helped fund the project.

But what happens next if this or another vaccine candidate successfully provides immunity against Covid-19? There have been mixed messages recently about how a vaccination programme would be handled.

How many doses?

Ministers have referred to “securing” 100 million doses of the Oxford vaccine – meaning that they have pre-ordered it in the hope that it will prove to be safe and effective in trials (the government has also hedged its bets by placing large orders with other vaccine developers).

The UK government is currently briefing journalists that if the Oxford vaccine is successful, the licensing agreement signed by the university and AstraZeneca back in May will deliver 100 million doses in total “for the UK”.

This sounds impressive: it would mean more than one dose for every one of the UK’s 67 million citizens – although we don’t know if multiple doses will be needed to provide enough immunity, as is the case with many vaccines.

But when the agreement was announced in May, it was made clear that not all of the 100 million doses were actually earmarked for people in Britain.

A government press release said: “If the Oxford vaccine is successful, AstraZeneca will work to make up to 30 million doses available by September for people in the UK, as part of an agreement to deliver 100 million doses in total.”

The Business Secretary Alok Sharma said: “The agreement will deliver 100 million doses in total, ensuring that in addition to supporting our own people, we are able to make the vaccines available to developing countries at the lowest possible cost.”

The fact that the 100 million vaccine doses are apparently not all destined to stay in Britain has only been rarely acknowledged since then.

The next detailed reference to it that we can find is in this August 18 letter from Professor Jonathan Van-Tam, the deputy chief medical officer, to Jeremy Hunt, who chairs the Health and Social Care Select Committee.

By August, it looked like the target had slipped from 30 million doses for UK use to 15 million:

FactCheck has asked the government whether anything has changed since August, or whether the plan is still to retain only 15 million doses of the pre-ordered 100 million for immediate use in Britain – enough for a single dose for less than a quarter of the population. We haven’t received a reply to this specific question.

Will Britain get the British vaccine first?

Back in May, the government said British people would get “first access” to the Oxford vaccine, a reflection of the fact that the project was helped by a massive investment from the UK taxpayer.

But it’s not clear how much control the British government will have over the global rollout of the vaccine.

We’re no longer talking about making 100 million doses in total worldwide.

AstraZeneca has now signed deals to supply many other countries around the world with the vaccine (at no profit), and says it now plans to make as many as 3 billion doses a year by partnering with other manufacturers around the world.

There’s another bit beyond Britain’s control: countries around the world will have their own regulators which will need to approve the use of the vaccine. They all work at different speeds.

Nevertheless, the government is sticking to its line here. A spokesperson for the Department for Business, Energy and Industrial Strategy told FactCheck: “The Government is committed to ensuring access to a vaccine as soon as is safely possible. This includes pre-ordering vaccines, ready for use the moment they have approval.

“If the vaccine being developed by the University of Oxford and AstraZeneca proves to be successful, people in the UK will get the first access to it, helping to protect thousands of lives.”

Will everyone in Britain be vaccinated?

Last week the Financial Times ran an article with Kate Bingham, the head of the government’s vaccine task forces.

Ms Bingham was quoted as saying that the government only aimed to vaccinate around 30m people – less than half the British population, and that there would be “no vaccination of people under 18”.

The government swiftly distanced itself from the claims made in the interview. Indeed, one government source told FactCheck that Ms Bingham’s comments “were misrepresented”.

A government spokesman said: “We want as many people as possible to access a Covid-19 vaccine. The independent Joint Committee for Vaccination and Immunisation advise Government on which groups of people to prioritise, based on the characteristics of the vaccine when it becomes available and the nature of the virus at the time of delivery, and we keep their advice under consideration.

“The committee’s interim advice is the vaccine should first be given to care home residents and staff, followed by people over 80 and health and social workers, then to the rest of the population in order of age and risk.

“An enormous amount of planning and preparation has taken place across Government to quickly roll out a safe and effective vaccine.”

The joint committee’s recommendations on who should be vaccinated first are here. The committee says its advice is “subject to change” and that the number of doses of vaccine that will be available is one of many “current uncertainties”.