4 months ago
Covid: What is the Oxford-AstraZeneca vaccine?
Covid: What is the Oxford-AstraZeneca vaccine?Published1 day agoSharecloseShare pageCopy linkAbout sharingRelated Topics
The Oxford-AstraZeneca vaccine may prevent people from spreading Covid, according to a new study.
It's the first time a vaccine has been shown to stop the transmission of the virus, as well as offering protection from becoming seriously ill and dying with it.
What are the findings?
The study, carried out by the University of Oxford, carried out weekly tests on people who had received the vaccine, to see if they were still carrying any trace of Covid.
The number who tested positive dropped by half after they had been given two doses of the vaccine.
If this study - which has not been formally published - is correct, it means that most people who are vaccinated protect other people too because they are not spreading the virus.
As well as showing an effect on transmission, the study found that a single dose of the vaccine offered 76% effective protection for three months. That means over seven out of 10 people who developed coronavirus had not had the actual vaccine.
How does the Oxford vaccine work?
It is made from a weakened version of a common cold virus (known as an adenovirus) from chimpanzees. It has been modified to look more like coronavirus - although it can't cause illness.
When the vaccine is injected into a patient, it prompts the immune system to start making antibodies and primes it to attack any coronavirus infection.
Research has shown it is highly effective. No one given the vaccine in trials developed severe Covid or needed hospital treatment.
Unlike Pfizer's jab - which has to be kept at an extremely cold temperature (-70C) - the Oxford vaccine can be stored in a normal fridge. This makes it much easier to distribute.
When was the vaccine approved?
The vaccine was approved for use by the MHRA (the UK's regulatory body) on 30 December
It was developed quickly because Oxford University researchers had already done a lot of work on developing a vaccine which could be adapted to tackle different diseases.
Hospitals administered the first doses to older patients early in January 2021.
Supplies were then sent to hundreds of GP-led services and care homes across the UK.
The MHRA approved the use of two full doses, which was found to be 62% effective.
And as with the other vaccines, scientists don't yet know if it stops people catching Covid - that's something they won't know until they can see the impact of vaccination over time.
Why are some European countries limiting their use of the vaccine?
Germany, Austria and France say they will only offer the vaccine to 18-64 year olds because there is not enough data on how well it protects the over-65s.
AstraZeneca says its clinical trial data "supports efficacy in the over-65s age group". Earlier studies show that older people, as well as younger people, appear to have an equally strong immune response to the vaccine.
Public Health England said the company's data on the vaccine's immune responses was "very reassuring".
The European Medicines Agency approved the vaccine in January for use in all age groups, including older adults.
Is the Oxford vaccine as good as the Pfizer?
Trials showed the Pfizer vaccine was 95% effective, but there were differences in the way the trials were carried out, so directly comparing the two results is difficult.
And it's important to remember that even the lower 62% figure is a better result than the best flu jab, which is about 50% effective.
What is more, no-one who received the Oxford vaccine was hospitalised or became seriously ill due to Covid.
How long do vaccines protect against Covid for?
A recent study found a single dose of the Oxford vaccine offered 76% protection for three months, and this went up to 82% after the second dose.
It is not yet known how long protection lasts in the long run, but a separate study found people are protected after being infected for at least six months - and vaccines are likely to provide longer protection than this.
It may be that people need annual vaccinations, as happens with the flu jab.
Which vaccine will I get?
You will not be given a choice about which vaccine you get.
Recommendations on which groups get the vaccine are made by the JCVI - the Joint Committee on Vaccination and Immunology - an independent group of scientists.
There are nine priority groups, amounting to more than 25 million people.
The over 80s, care home residents and front-line health and care staff have been offered the jabs first.
It will then be rolled out to other groups including all the over 50s and younger adults with health conditions.
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