By Guy Faulconbridge, Kate Kelland and Kate Holton

LONDON (Reuters) – One of the world’s leading COVID-19 experimental vaccines produces a immune response in both old and young adults, raising hopes of a path out of the gloom and economic destruction wrought by the novel coronavirus.

The vaccine, developed by the University of Oxford, also triggers lower adverse responses among the elderly, British drug maker AstraZeneca Plc <AZN.L>, which is helping manufacture the vaccine, said on Monday.

A vaccine that works is seen as a game-changer in the battle against the novel coronavirus, which has killed more than 1.15 million people, shuttered swathes of the global economy and turned normal life upside down for billions of people.

“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,” an AstraZeneca spokesman said.

“The results further build the body of evidence for the safety and immunogenicity of AZD1222,” the spokesman said, referring to the technical name of the vaccine.

AstraZeneca did not provide detail of the data behind the statement or say when it would publish eagerly awaited late-stage phase III trial data, which would show whether the vaccine works well enough in large scale trials for it to be approved.

The Oxford/AstraZeneca vaccine is expected to be one of the first from big pharma to secure regulatory approval, along with Pfizer <PFE.N> and BioNTech’s <22UAy.F> candidate.

The news that older people get an immune response from the vaccine is positive because the immune system weakens with age and older people are those most at risk of dying from the virus.

If it works, a vaccine would allow the world to return to some measure of normality after the tumult of the pandemic.

British Health Secretary Matt Hancock said a vaccine was not yet ready but he was preparing logistics for a possible roll out mostly in the first half of 2021.

Asked if some people could receive a vaccine this year he told the BBC: “I don’t rule that out but that is not my central expectation.”

COMMON COLD VIRUS

Work began on the Oxford vaccine in January. Called AZD1222 or ChAdOx1 nCoV-19, the viral vector vaccine is made from a weakened version of a common cold virus that causes infections in chimpanzees.

Immunogenicity blood tests carried out on a subset of older participants echo data released in July which showed the vaccine generated “robust immune responses” in a group of healthy adults aged between 18 and 55, the Financial Times reported earlier.

“We need to see the data before concluding that the responses were ‘similar’,” Stephen Evans, a professor of pharmacoepidemiology at London School of Hygiene & Tropical Medicine, said.

He said that reactogenecity, which refers to common side-effects of vaccines like soreness and redness of the arm, was “often, but not always” associated with a vaccine’s immunogenicity.

“Studies carried out in the first stage of development of a vaccine will result in choosing a dose that does not cause too much reactogenicity,” he said.

AstraZeneca has signed several supply and manufacturing deals with companies and governments around the world as it gets closer to reporting early results of a late-stage clinical trial.

It resumed the U.S. trial of the experimental vaccine after approval by U.S. regulators, the company said on Friday.

Staff at a London hospital trust have been told to be ready to receive the first batches of the Oxford/AstraZeneca vaccine, The Sun newspaper reported on Monday.

(Additional reporting by Bhargav Acharya and Kanishka Singh in Bengaluru; Writing by Guy Faulconbridge in London; Editing by Angus MacSwan)