A LEADING experimental vaccine for Covid-19 produces a "strong immune response” in both older and younger adults, raising hopes of an end to the pandemic.

Information from an earlier stage of the Oxford University and AstraZeneca vaccine candidate trial suggests "similar" immune responses all adult patients, scientists said.

Data on the safety and immune responses among those taking part in the phase two vaccine trial has been submitted for peer review in a medical journal.

But the findings have been discussed before publication, prompting more excitement about the vaccine – considered one of the forerunners in the Covid-19 vaccine race.

The vaccine is currently in a phase three clinical trial, which means the safety and effectiveness of the vaccine is being tested by thousands of participants across a number of different countries.

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Experts have predicted that the data from the trial could be presented to regulators within weeks.

It comes as the UK Health Secretary said that the "bulk" of the rollout of a coronavirus vaccine could occur before next summer.

Matt Hancock said that his "central expectation" is that the majority of the rollout of a vaccine could be under way in the first half of 2021.

In a statement, Oxford University said: "Professor (Andrew) Pollard discussed the early findings of the Phase II safety and immunogenicity trial of the ChAdOx1 nCov-2019 Oxford coronavirus vaccine at a research conference.

"These early results covering trial volunteers from the UK in the 56-69 and 70+ age groups have been submitted to a peer-review journal, and we hope to see their publication in the coming weeks.

"Our ongoing trials will provide further data, but this marks a key milestone and reassures us that the vaccine is safe for use and induces strong immune responses in both parts of the immune system in all adult groups."

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An AstraZeneca spokesperson added: "It is encouraging to see immunogenicity responses were similar between older and younger adults and that reactogenicity was lower in older adults, where the Covid-19 disease severity is higher.

"The results further build the body of evidence for the safety and immunogenicity of AZD1222."

Clinical trials for Covid-19 vaccines are ongoing. Some have speculated that two vaccine candidates will report data to regulators this year.

When asked about reports that hospitals are preparing to vaccinate staff, Hancock said: "We want to be ready in case everything goes perfectly."

"We don't know when the first vaccine will be available but my central expectation is in the first half of next year.

"Nevertheless, we're doing the preparatory work now for how that will be rolled out, the Joint Committee on Vaccinations and Immunisations has set out the order of priority; and we're doing the logistical work, led by the NHS working with the armed services who are playing an important role in the logistics of it to ensure that we have that rollout programme ready.

"But, you know, preparing for a rollout and actually having the stuff to roll out are two different things. It's obviously something that we want to happen as soon as safely can be done.

"And as fast as safely can be done, but we are not there yet."

Commenting on the news from Oxford and Astrazeneca, Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene and Tropical Medicine, said: "In order to comment properly on this we need to see the data. It is encouraging that the investigators suggest that the immune responses measured in the blood seem to show efficacy both above, as well as below, age 70.

"The later phase trials are needed to see if the immune responses translate into clinical efficacy in preventing infection. These will involve much larger numbers and it is wise to not be too optimistic until those trials have completed."

Professor Robert Read, head of clinical and experimental sciences within medicine at the University of Southampton, added: "Previous data had shown the vaccine induces an immune response in younger people – it sounds like there is early data suggesting the same happens in older adults, which would be reassuring, but we haven't seen the data yet.

"This is very encouraging, but we still need to wait a little longer for information on protection from natural disease and overall safety in field trials.

"The fact that reactogenicity – adverse events after vaccination, such as sore arm/fever etc – is said to be relatively low in older adults is also very reassuring."