The government’s latest prediction is that our lives will “start returning to normal” by Easter 2021. After a flurry of hugely encouraging vaccine trial results – the Oxford/AstraZeneca candidate could be up to 90% effective with the right dosage regimen – there is better reason than ever to be optimistic. Now the question is when, not if, life will return to “normal” – whatever that is.

But we’ve been here before. In March, Boris Johnson was confident that “we can turn the tide” on the virus within 12 weeks. In July, he predicted that we’d be back living our ordinary lives again by Christmas.

The truth is nobody knew then and nobody knows now. So, should we trust this latest date of deliverance any more than those that have gone before it?

The short answer is: yes, a little bit.

The roadmap for mass immunisation is now clear, though obstacles remain. The first step is for the vaccines to be approved for mass use. British regulators are about to start a formal appraisal of the Pfizer jab with hopes that it could pass within a week. The NHS has been told to prepare to start distributing the first 10 million of the 40 million pre-ordered doses as early as 1 December.

Moderna chiefs are hoping to have their vaccine approved by the end of the year. The 5 million doses earmarked for the UK will be extremely useful, but they are not likely to make a significant difference until later in the spring.

The Oxford vaccine, of which the government has ordered 100 million doses, is expected to make the biggest impact. The Medical and Healthcare products Regulatory Agency (MHRA) – an independent regulator – will assess the Oxford trial data, assisted by the Commission on Human Medicines, the UK government’s independent advisory body, in the coming days.

According to Professor Sir Gordon Duff, a former chair of the MHRA, if the Oxford vaccine is deemed safe then it shouldn’t take more than ten weeks for it to start being rolled out. “If all goes well… and if there aren’t any points of information lacking then 2 or 3 weeks could be possible,” he said.

Gaining approval is not a foregone conclusion. And many questions remain unanswered, such as whether the vaccine prevents asymptomatic infection and how long immunisation lasts.

But if the Oxford vaccine is approved this quickly, up to 4 million doses would be available by the end of the year. Those most at risk and frontline health workers will be vaccinated first, although leaked documents seen by the Health Service Journal have revealed that the NHS plans to start vaccinating the entire adult population by the end of January, with the aim of getting 75% of the country vaccinated before 1 May.

Professor Sir John Bell, Regius Professor of Medicine at the University of Oxford and a member of the UK vaccine task force, says that he is now “more confident” than he was two weeks ago when he told the House of Commons that there was a “70 to 80 percent chance of normality post-Easter… that’s provided they don’t screw up the distribution.”

Because the Oxford vaccine doses won’t need to be stored in a super-cooled freezer, unlike Pfizer’s, and can instead be kept in a normal fridge, one of the biggest logistical impediments to distributing an effective vaccine seems to have been sidestepped. The NHS also has an excellent track record on delivering vaccinations, with 15 million high-risk individuals given flu jabs every Autumn.

But there is still the possibility of a third wave of coronavirus hampering distribution. Planners are worried that the country’s collective behaviour, particularly over Christmas, could lead to a peak in infections that would complicate the vast logistical operation, for which the army will likely be required.

One of the biggest obstacles will probably be human – a large fraction of the country might refuse to be vaccinated. It is estimated that 60 to 70% of the population would need to be immunised in order to achieve herd immunity – the point at which virus transmission drastically reduces. Reaching this level is widely considered a necessary condition for a return to a world without social distancing.

But a recent report has shown that 9% of the country are adamantly opposed to being vaccinated and 26% are uncertain whether they will or not. That doesn’t leave much wiggle room.

Insiders see the summer as being a more realistic guess for a return to normality. According to Professor Calum Semple, a member of the government’s SAGE committee, “we will be seeing a lifting of restrictions in the spring.” But widespread immunity that would allow for a full roll back of restrictions wouldn’t come for a few more months.

“The vaccine priorities will inevitably be the most vulnerable and the frontline health care workers,” he said. “For the rest of the population I think we’ll be looking towards the summer before there is mass vaccination [which] will give us the broad immunity that allows us to return to normal.”

England’s Chief Medical Officer, Professor Chris Whitty – previously far more cautious than Johnson – has backed the PM’s claim of a return to normality from the spring when “we’ll be able to pull back from these really oppressive things we have to do socially and economically”.

Despite his optimism, Sir John Bell believes that the full shift to post-pandemic life will take time. “It’s really important for everyone to realise this isn’t going to happen instantaneously,” he said. “It’s going to be a gradual migration… people [going] to work, people riding the subways, things looking much more normal than they do now.”

It’s not unlikely that Easter marks the beginning of the end or, at the very least, the end of the beginning. But there are simply too many unknowns to be sure. Even though the future is now looking much brighter, the government should stop making promises it might not be able to keep.