How does the Oxford vaccine differ to Pfizer’s?

The Oxford trial vaccine
The Oxford trial vaccine (PA Media)
9:34am, Tue 10 Nov 2020
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The AstraZeneca Oxford University vaccine has been a frontrunner in the race to find a coronavirus jab and is expected to report its first results within weeks.

– How does the AstraZeneca/Oxford vaccine work?

The vaccine – called ChAdOx1 nCoV-19 – uses a weakened version of a common cold virus which causes infections in chimpanzees, but has been genetically changed 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.

This enables the human body to identify coronavirus and create an immune system response.

– Does it differ to Pfizer’s vaccine?

Yes. Pfizer’s jab is a messenger RNA (mRNA) vaccine.

How the RNA vaccine would work (PA Graphics)

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 actual 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?

AstraZeneca and Pfizer’s 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 an antibody and a T-cell response.

A study on the AstraZeneca vaccine found that levels of T-cells peaked 14 days after vaccination and antibody levels peaked after 28 days.

– Can the Oxford vaccine be manufactured to scale?

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

Covid-19 vaccine tracker (PA Graphics)

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

– Can this vaccine help the elderly?

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

However, data from the Oxford University and AstraZeneca vaccine trial suggests there have been “similar” immune responses among younger and older adults.

In a statement, Oxford University said its data marked a “key milestone”, with the vaccine inducing strong immune responses in all adult groups.

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