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

The University of Oxford coronavirus vaccine produces a strong immune response in older adults, the latest trial results show, in another boost in the fight against Covid-19.

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

Phase two data, published in The Lancet, suggests one of the groups most vulnerable to serious illness and death from Covid-19 could build immunity, researchers say.

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

UK authorities have placed orders for 100 million doses of the vaccine – 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.

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.

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.

What happens next?

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

UK authorities have placed orders for 100 million doses of the vaccine – enough to vaccinate most of the population – should it receive regulatory approval.

You may also like...