Hopes of ending the Covid-19 pandemic with a vaccine grew today after promising data revealed Oxford University’s experimental jab is safe and provoke an immune reaction that lasts for at least two months.

Hugely-anticipated clinical trial results of the vaccine — one of the front-runners in the world’s race for a jab — revealed more than 91 per cent of volunteers injected produced an immune response against the coronavirus that lasted a month or more. 

Immune responses remained strong for at least 56 days, according to results in The Lancet. But it won’t be licensed for human use yet because it has not been proven to work and the results only show it has promise.

The scientists who did the study, however, said it is ‘possible’ that the vaccine could be ready by December if tests keep going according to plan. Another added that people in the most at-risk groups could get the first jabs in the winter.

Crucially, nobody suffered any bad side effects from the vaccine and it is stimulating the immune system as scientists hoped. Some people developed headaches, tiredness and pain in their arm after they were given the jab, but scientists claimed none of the side effects were severe. 

Oxford University’s vaccine — called AZD1222 — is already being manufactured by pharmaceutical giant AstraZeneca and the UK Government has ordered 100million doses ahead of time.

Researchers on the project said ‘the early results hold promise’ but added much more is still needed.’ Infectious disease scientists warned ‘there is still a long way to go’ before any vaccine is rolled out. 

If the vaccine is given to the public it is likely to be in two doses given close together, developers said, because that seems to strengthen the body’s response.

The eagerly awaited results come after Prime Minister Boris Johnson this morning tried to temper expectations when he admitted he wasn’t totally confident there would even be a vaccine by the end of next year.

Ministers did, however, today announce deals for a further 90million doses of two types of experimental jab being developed in France and Germany. Britain is shoring up stocks of vaccines in development all over the world in its spread-betting approach in the hope that at least one of them will pay off. 

Results from the first phase of clinical trials of Oxford’s vaccine were published today in the British medical journal, The Lancet.

They revealed that the Covid-19 vaccine, named AZD1222, had been given to 543 people out of a group of 1,077. 

The other half were given a meningitis jab so their reactions could be compared and scientists could be sure the effects of the coronavirus jab weren’t random.   

Researchers wanted to find out whether the vaccine boosted either of two types of immunity — antibodies, which are disease-fighting substances; and T-cell immunity, with T cells able to produce antibodies and also to attack viruses themselves.

The vaccine produced ‘strong’ responses on both accounts, the study found, with T cell immunity peaking after two weeks and then dropping slightly by day 56.

Antibody immunity, on the other hand, peaked after four weeks and remained high by day 56, the point at which the last measurement was taken, meaning it may well last for even longer.

After 28 days, up to 100 per cent of a group of 35 people still had a strong enough ‘neutralising’ immune response to destroy the virus, researchers found. 

Professor Sarah Gilbert, one of the scientists leading the project, said: ‘There is still much work to be done before we can confirm if our vaccine will help manage the Covid-19 pandemic, but these early results hold promise. 

‘As well as continuing to test our vaccine in phase 3 trials, we need to learn more about the virus – for example, we still do not know how strong an immune response we need to provoke to effectively protect against SARS-CoV-2 infection. 

‘If our vaccine is effective, it is a promising option as these types of vaccine can be manufactured at large scale. 

‘A successful vaccine against SARS-CoV-2 could be used to prevent infection, disease and death in the whole population, with high risk populations such as hospital workers and older adults prioritised to receive vaccination.’ 

Health Secretary Matt Hancock said the update on the vaccine was ‘very encouraging news’.

Congratulating the Oxford team and praising the ‘leadership’ of AstraZeneca, he tweeted: ‘We have already ordered 100 million doses of this vaccine, should it succeed.’ 

Boris Johnson tweeted: ‘This is very positive news. A huge well done to our brilliant, world-leading scientists & researchers at @UniofOxford.

‘There are no guarantees, we’re not there yet & further trials will be necessary – but this is an important step in the right direction.’

The results of the trial came after announcements earlier today that the Government has bought orders for two other potential vaccines from France and Germany. 

Agreement has been reached for 30million doses from German firm BioNTech and the US company Pfizer, and 60million doses from France’s Valneva.

The figure is in addition to the 100million doses of vaccine that are being developed by Oxford University in partnership with AstraZeneca, as well as another at Imperial College London which started human trials in June.

But the Prime Minister remained realistic about the prospects of a jab, saying people couldn’t rely on one being made. 

Speaking on Sky News this morning, Mr Johnson said: ‘I wish I could say that I was 100 per cent confident we’ll get a vaccine for Covid-19.

‘We just need to wait and see what the clinical trials tell us but I think again it’s important to recognise that it’s unlikely to be a single vaccine for everybody. We may well need different vaccines for different groups of people.’

Ms Bingham said that although it would be ideal to have a ‘sterilising’ vaccine that would completely stop the virus, that could be too ambitious. 

‘I think we may need to start off with and recognise is that the vaccines may just stop the level of mortality so we may just find a vaccine that helps reduce the symptoms rather than provides a full sterilising immunity

‘If I look with my rose-tinted specs, I think they [Oxford University] could get data by the end of the year. They’re running studies in the UK and in Brazil and South Africa. 

‘What I would hope we would see is strong safety data in all of the relevant populations who are most at risk which will come out in the UK trial. And I would hope to see efficacy signals which means data that shows the vaccine prevent infection or reduce the symptoms coming out of those two studies.

‘It all depends on how much infection we see. The regulators will need to look at the data and every aspect of the vaccine and then they will take a view on whether this is a vaccine that should be licensed for use more broadly.’

Ms Bingham added that she was hopeful getting a vaccine by the end of the year was ‘still possible’ but such low numbers of coronavirus cases make it difficult to test one in Britain. 

Valneva, the French company developing a vaccine that the UK has bought 60m doses, it creating a jab based on injecting people with dead versions of the coronavirus.

This is called an inactivated whole virus vaccine and works by injecting the virus itself but versions that have been damaged in a lab so that they cannot infect human cells. They can be damaged using heat, chemicals or radiation.

Even though the viruses are inactivated the body still recognises them as threats and mounts and immune response against them which can develop immunity.

The BioNTech vaccine, on the other hand, is one which injects RNA – genetic material – which codes the body to produce proteins that look like the spike proteins that would be found on the outside of the real coronavirus.

AstraZeneca, which is working in partnership with Oxford University, is already manufacturing a vaccine in the hope that it will work. The UK Government agreed to buy them without seeing results of clinical trials, which have not been completed yet.

But the team from Oxford, and another working on a different jab made by the American pharmaceutical company Moderna, have both revealed people in their studies are showing signs of immunity.

Each has been working on separate experimental jabs for months to try to protect millions of people from catching the coronavirus in future.    

People being given the Oxford vaccine have been developing antibodies and white blood cells called T cells which will help their bodies fight off the virus if they get infected, it is reported.

And experts at Moderna, based in Cambridge, Massachusetts, said participants in their trial – of a different type of vaccine – all successfully developed antibodies.

The vaccines work by tricking the body into thinking it’s infected with Covid-19 and causing it to produce immune substances that have the ability to destroy it.

While early research focused on antibodies, scientists are increasingly turning to a type of immunity called T cell immunity — which is controlled by white blood cells — which has shown signs of promise.

One source on the Oxford project told ITV News: ‘An important point to keep in mind is that there are two dimensions to the immune response: antibodies and T-cells. 

‘Everybody is focused on antibodies but there is a growing body of evidence suggesting that the T-cells response is important in the defence against coronavirus.’

Oxford’s phase 3 trial is involving around 8,000 people across the UK and also up to 6,000 people in Brazil and South Africa, where the jab may be easier to test because more people are infected with the coronavirus.

The vaccine is being manufactured by AstraZeneca, based in Cambridge, England, and millions of doses have already been ordered by Number 10 in the hope that it will work. 

In the early stages researchers will want to see that the jab is safe for people to take and doesn’t cause serious side effects, and also that it seems to be stimulating the immune system in the right way.

If it passes these checkpoints researchers are expected to move on to even larger tests with thousands more members of the public.

In its own tests Moderna, the US pharmaceutical company, reports that its vaccine has passed these early milestones and now plans to move on to bigger trials.

Researchers at the company last night announced that all 45 volunteers in its early phase had developed immune responses after being given the vaccine.

They also found the jab — one of the front-runners in the global coronavirus vaccine race — was safe and no participants suffered any serious side effects. 

But more than half reported mild or moderate reactions such as fatigue, headache, chills, muscle aches or pain at the injection site. 

Scientists said side effects were a ‘small price to pay’ for protection against Covid-19. 

Dr Anthony Fauci, the US government’s top infectious disease expert, said: ‘No matter how you slice this, this is good news.’  

Moderna was the first US company to start human testing of a vaccine for the novel coronavirus on March 16, 66 days after the genetic sequence of the pathogen was released by China.

It’s now preparing to start a 30,000-person trial later this month to prove the vaccine really is strong enough to protect against the coronavirus. 

The share price of the company surged on the news as it stoked hopes of progress in the global battle against Covid-19.

The US federal government is supporting Moderna’s vaccine with nearly half a billion dollars in funding. 

Its vaccine, known as mRNA-1273, works using ribonucleic acid (RNA), which is a chemical messenger in human bodies that contains instructions for making proteins. 

The jab introduces RNA which programmes the body to make proteins that look like those found on the surface of the coronavirus, which triggers the immune system to react because it recognises those proteins as a danger – even though they aren’t actually attached to a virus and can’t cause any harm. 

This then trains the body to recognise these as a foreign invader, and mount an immune response against it.

The results, published in the prestigious New England Journal of Medicine, involved three groups of 15 volunteers aged 18-55.

The groups tested 25, 100 or 250 micrograms of the vaccine. Everyone got two doses, 28 days apart. 

The team reported a dose-dependent effect, whereby the participants grew a larger antibody response the higher their vaccination dose was. 

In comparison, the University of Oxford team’s jab works by injecting a damaged part of the real coronavirus that has been attached to another, harmless, virus.

It’s a type of immunisation known as a recombinant viral vector vaccine. 

Researchers place genetic material from the coronavirus into another virus that’s been modified. They will then inject the virus into a human, hoping to produce an immune response against SARS-CoV-2. 

The carrier virus, weakened by genetic engineering so it doesn’t make people ill, is a type of virus called an adenovirus, the same as those which cause common colds, that has been taken from chimpanzees. 

If the vaccines can successfully mimic the spikes that are found on the outside of Covid-19 inside a person’s bloodstream, and stimulate the immune system to create special antibodies to attack it, this could train the body to destroy the real coronavirus if they get infected with it in future.

One of the other leading vaccine candidates, being made by Imperial College London, works in a similar way to Moderna’s, instead of Oxford’s.    

It will try to deliver genetic material (RNA) from the coronavirus which programs cells inside the patient’s body to recreate the spike proteins. It will transport the RNA inside liquid droplets injected into the bloodstream.

Oxford’s vaccine could be developed so rapidly by Professor Sarah Gilbert, a vaccinology expert, and her team because they already had a base vaccine for similar coronaviruses. 

Professor Gilbert said earlier this month that protection from a jab against coronavirus should last for several years at least.

She told MPs she was optimistic that a vaccine would provide ‘a good duration of immunity’.

Professor Gilbert is the world-renowned expert leading an Oxford University team devising a vaccine, so her claim could help to dispel the fears over how long protection against Covid-19 might last.

Concerns had been raised after those with other types of coronavirus – which are less dangerous and cause the common cold – were able, in tests, to be reinfected within a year.

But Professor Gilbert told the Commons science and technology committee there may be a better result from a vaccine than the natural immunity acquired when individuals simply recover from a virus. 

She said: ‘Vaccines have a different way of engaging with the immune system, and we follow people in our studies using the same type of technology to make the vaccines for several years, and we still see strong immune responses.

‘It’s something we have to test and follow over time – we can’t know until we actually have the data.

‘But we’re optimistic based on earlier studies that we will see a good duration of immunity, for several years at least, and probably better than naturally-acquired immunity.’ 

The key question is whether the vaccine will protect them from becoming infected, or simply make them less ill. It may also work less well in older people because their immune systems are weaker.

Sir John Bell, regius professor of medicine at Oxford University, also gave evidence to the committee, warning that the UK must ‘prepare for the worst’ this winter, rather than rely on the development of a vaccine.