Oxford Covid-19 vaccine Q&A: what do the results show so far, and what happens next?

Tests show the University of Oxford coronavirus vaccine produces a strong immune response in older adults and scientists hope results will be ready by Christmas.

In a ‘rolling review’ designed to speed up the process, the Oxford team have given regulators access to information to assess before they produce a final clinical data set, according to Prof Sarah Gilbert, lead researcher of Oxford’s vaccine development programme.

The vaccine, named ChAdOx1 nCov-2019, has been shown to trigger a robust immune response in healthy adults aged 56-69 and people over 70.

Phase three trials of the vaccine are ongoing, with early efficacy readings possible in the coming weeks.

Despite this, however, Oxford’s scientists said they would not rush to publish the results of their efficiency trial, after the chair of the Oxford vaccine group, Professor Andrew Pollard, declared they were not in competition with the Pfizer and Moderna, who released their promising results last week, which were around 95 per cent effective.

“We are not in a rush,” the professor shared. 

“It’s not a competition with the other developers. We’re trying to make sure we have very high quality data, working with other partners in other countries. When it’s ready is when we will publish the interim results.”

Professor Pollard’s comments come after expectations that 100m doses of the Oxford vaccine, ordered by the UK authorities, would be available for Christmas. This would be enough to vaccinate most of the population – should it receive regulatory approval. 

How does the AstraZeneca/Oxford vaccine work?

The vaccine – called ChAdOx1 nCoV-19 – uses a harmless, weakened version of a common virus which causes a cold in chimpanzees.

Researchers have already used this technology to produce vaccines against a number of pathogens including flu, Zika and Middle East respiratory syndrome (Mers).

The virus is genetically modified so it is impossible for it to grow in humans.

Scientists have transferred the genetic instructions for coronavirus’s specific "spike protein" – which it needs to invade cells – to the vaccine.

When the vaccine enters cells inside the body, it uses this genetic code to produce the surface spike protein of the coronavirus.

This induces an immune response, priming the immune system to attack coronavirus if it infects the body.

How does the Oxford vaccine work?

What do the results show?

The ChAdOx1 nCov-2019 vaccine has been shown to trigger a robust immune response in healthy adults aged 56-69 and people over 70.

According to the researchers, volunteers in the trial demonstrated similar immune responses across all three age groups (18-55, 56-69, and 70 and over).

The study of 560 healthy adults – including 240 over the age of 70 – found the vaccine is better tolerated in older people compared with younger adults.

Volunteers received two doses of the vaccine candidate, or a placebo meningitis vaccine.

No serious adverse health events related to the vaccine were seen in the participants.

The results are consistent with phase one data reported for healthy adults aged 18-55 earlier this year.

Does it differ to Pfizer and Moderna’s vaccines?

Yes. The jabs from Pfizer and Moderna are messenger RNA (mRNA) vaccines.

Conventional vaccines are produced using weakened forms of the virus, but mRNAs use only the virus’s genetic code.

An mRNA vaccine is injected into the body where it enters cells and tells them to create antigens.

These antigens are recognised by the immune system and prepare it to fight coronavirus.

No virus is needed to create an mRNA vaccine. This means the rate at which the vaccine can be produced is accelerated. 

 On November 20, however, Pfizer/ BioNTech they had sent their vaccine for emergency approval in the US. They are the first pharmaceutical organisation to apply for such authorisation for a coronavirus vaccine, and approval would mean that the first shipment will leave ‘within hours’. This suggests people in the UK may receive the Pfizer by early-mid December.

What about antibodies and T-cells?

The Pfizer, AstraZeneca and Moderna vaccines have been shown to provoke both an antibody and T-cell response.

Antibodies are proteins that bind to the body’s foreign invaders and tell the immune system it needs to take action.

T-cells are a type of white blood cell which hunt down infected cells in the body and destroy them.

Nearly all effective vaccines induce both responses.

The Oxford vaccine induces robust antibody and T-cell responses across people of all ages, the data indicates.

Can the Oxford vaccine be manufactured to scale?

Yes. The UK Government has secured 100 million doses as part of its contract, enough for most of the population.

The head of the UK Vaccine Taskforce, Kate Bingham, has said she is confident it can be produced at scale.

Experts hope the jab could be ready to go and rolled out shortly.

Vaccines secured by the government and current state of development 

Can this vaccine help the elderly?

There have been concerns that a Covid-19 vaccine will not work as well on elderly people, much like the annual flu jab.

However, data from the Oxford-AstraZeneca trial suggests there have been "similar" immune responses among younger and older adults.

The results show that the vaccine is better tolerated in older people compared with younger adults, and produces a similar immune response in old and young adults.

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