As the Pfizer Covid-19 vaccine rollout began in the UK this week questions remain about how long the vaccine will last.

Heralded as a “game changer” in the fight against the coronavirus crisis that has gripped the world for months, research remain limited, although it has been comfirmed as safe by experts.

Designed to allow a person to develop the antibodies needed to fight the virus without them having to have contracted it first, the vaccine uses only the virus’s genetic code, rather than an active ingredient.

An mRNA vaccine is injected into the body where it enters cells and tells them to create antigens and antibodies, which are recognised by the immune system and prepare it to fight coronavirus.

While vaccines that use active ingredients like softened or weakened forms of a pathogen are also extremely safe, using just the code makes the Covid-19 vaccine even less of a risk to vulnerable patients.

But how long do these antigens last in the body, and if you are lucky enough to receive the vaccine, does that then make you completely safe from Covid-19 forever?

Here is everything you need to know:

How long does the vaccine last?

Despite the good news of a vaccine, it's still not 100 per cent known how long the vaccines (the already available Pfizer jab, and the two other immunisations still in the preliminary stages of approval) remain effective, though it is expected to be a considerable amount of time.

In July, the University of Oxford claimed their vaccine lasted for over 56 days; the only reason that amount of time isn’t longer, is because the research ended at the 56-day mark.

On 2 December, Health Secretary Matt Hancock said that vaccines could be re-procured if they are needed again over the longer term, if the vaccine is only “short term” .

He added that patients could be retreated either “through re-procurement of one of the existing vaccines or by switching to a different vaccine if that is clinically appropriate.”

Does the vaccine stop a person passing on the virus to others?

Though you may have the antibodies needed to quickly flush the virus from your system should it come into contact with it again, does the vaccine prevent you from passing on the disease to others asymptomatically?

Matt Hancock warned that it is still unknown to what extent the Covid-19 vaccine can prevent someone passing on the disease.

Appearing on BBC Breakfast, he said: “We know that this vaccine protects the person who’s been vaccinated. What we don’t yet know is the degree to which the vaccine reduces the chance of Margaret [Keenan, the first person in the world to receive the jab] passing it on asymptomatically.

“We think that that transmission risk, as it’s called, is much reduced by being vaccinated. But we need to watch that.”

Speaking on the same programme, Christine Tait-Burkard, assistant professor of immunology at the University of Edinburgh, said “every percentage” of people vaccinated should make a difference to the rate of transmission if a vaccine provides “viral immunity” and stops people shedding the virus.

“But that’s where we still have some question marks around some of the vaccines,” she added, “because that is actually parts that’s not being looked at in the clinical trials studies just now.”

When will life get back to normal?

Restrictions and lockdown measures have taken their toll on people around the world, and many will be wondering whether the vaccine means normality may return quicker than first expected.

The Government’s chief scientific adviser has warned that restrictions could be here to stay for the foreseeable future, and the UK is unlikely to get back to a semblance of normality before spring 2021.

Speaking to Sky News, Sir Patrick Vallance: “It’s going to take quite a long time to make sure everybody in the at-risk groups and all of the groups that are difficult to reach get vaccinated as appropriate.”

He said it will be at least a month or more before the effects of the vaccine begin to be seen, adding: “It is important we all stick to the rules in the meantime – the rules are what’s keeping the virus down.”

Sir Patrick said: “It may be that next winter even with vaccination we need measures like masks in place – we don’t know yet how good all the vaccines are going to be at preventing the transmission of the virus.”

A version of this article originally appeared on our sister title, the Scotsman