Since the start of the pandemic, scientists
around the world have been racing to develop a vaccine that prevents Covid-19.
In December, the Pfizer/BioNTech coronavirus
vaccine beat its rivals to be the first approved for use in the UK. Two more
vaccines, from Moderna and Oxford/AstraZeneca, have since been authorised, and
there is a fourth, fifth, and sixth potentially on the way.
One is the Janssen vaccine, from American
company Johnson & Johnson, the world’s first single-shot Covid vaccine,
which was found to be 66% effective at preventing moderate to severe Covid-19
but offers high protection against people needing to go to hospital, according
to trial results.
Meanwhile, the Government has ordered 60
million doses of another Covid vaccine candidate from Novavax, which is due to
be made on Teeside if approved. The vaccine was found to be 80.3% effective at
preventing Covid-19 in UK trials and worked against the new Kent and South
The large-scale manufacturing of another
potential vaccine made by the French company Valneva, started in Scotland in
January. It is expected to deliver up to 60 million doses to the UK by the end
of this year if approved.
Here are the differences between the
have shown the Pfizer/BioNtech vaccine to be more than 90% effective, but it
has to be stored at minus 70 degrees C so is not the easiest vaccine to use.
Patients need two doses.
It is known as a messenger RNA (mRNA)
vaccine. 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 it can
be produced is dramatically accelerated. As a result, mRNA vaccines have been
hailed as potentially offering a rapid solution to new outbreaks of infectious
In theory, they can also be modified
reasonably quickly if, for example, a virus develops mutations and begins to
change. mRNA vaccines are also cheaper to produce than traditional vaccines,
although both will play an important role in tackling Covid-19. One downside to
mRNA vaccines is that they need to be stored at ultra-cold temperatures and
cannot be transported easily.
vaccine works in a similar way to the vaccine from Pfizer/BioNTech.
Coronavirus is studded with ‘spike proteins’
that it uses to enter human cells. Covid-19 vaccines target this spike protein.
The Moderna and Pfizer vaccines use synthetic messenger RNA (mRNA), a genetic
material that contains information about the spike protein. The vaccines
provide the body with instructions to produce a small amount of this protein
which, once detected by the immune system, leads to a protective antibody
Moderna’s vaccine does not require the same
ultracold storage as Pfizer’s and can remain stable at normal fridge
temperature for 30 days. Trials on more than 30,000 people in the US have shown
the Moderna vaccine to be 94% effective in preventing coronavirus and Moderna
has not identified any significant safety concerns and its vaccine has been
approved for use in the US.
The MHRA accepted the recommendation of the
Commission on Human Medicines and authorised the Moderna Vaccine on January 8,
The vaccine developed by the University of
Oxford and pharmaceutical giant AstraZeneca was approved by the MHRA in
December last year. The Oxford vaccine is not an mRNA vaccine. Instead, it uses
a harmless weakened version of a virus that causes the common cold in
Oxford data indicates the vaccine has 62%
efficacy when one full dose is given followed by another full dose, but when
people were given a half dose followed by a full dose at least a month later,
its efficacy rose to 90%. The combined analysis from both dosing regimes
resulted in an average efficacy of 70.4 %. In separate research, results showed
the vaccine offers 76% protection up to three months after the first dose and
could reduce transmission by 67%.
However, a study of around 2,000 people has
shown the vaccine only offers minimal protection against mild disease of the
South Africa variant and, due to the young age of participants, could not
conclude whether the vaccine worked against severe disease.
Health minister Edward Argar said on Monday
that Oxford researchers remained confident their vaccine could prevent severe
disease for those affected by the variant and that booster vaccines to tackle
new strains are already in the pipeline.
trials are still ongoing for this vaccine, but manufacturing has started at the
French biotech company’s site in Livingston, West Lothian. The candidate is
currently in phase one/two trials and will need approval from the Medicines and
Healthcare products Regulatory Agency (MHRA) before it is rolled out. Initial
results from the ongoing clinical study, involving 150 participants at testing
sites in Bristol, Southampton, Birmingham and Newcastle, are expected in April.
The vaccine works by using technology already
used in existing vaccines that are used for prevention of diseases such as as
the flu and Japanese encephalitis. It uses inactivated whole particles of
SARS-CoV-2 to induce a strong immune response.
fourth Covid-19 vaccine could be approved for use in the UK within weeks, as
late-stage trials suggested it was 89% effective in preventing coronavirus. The
vaccine is the first to show in trials that it is effective against the new
virus variant found in the UK.
The UK has secured 60 million doses of the
vaccine – to be produced on Teesside – which is believed to offer protection
against the new UK and South African variants.
It was shown to be 89.3% effective at
preventing coronavirus in participants in its Phase 3 clinical trial in the UK,
which involved more than 15,000 people aged between 18-84, of which 27% were
older than 65, Novavax said.
The vaccine will now be assessed by the
Medicines and Healthcare products Regulatory Agency (MHRA), Prime Minister
Boris Johnson said.
Pfizer and Moderna vaccines rely on
technology that has not been used in previous vaccines, but the Novavax vaccine
uses a more traditional method of recreating part of the spike protein of the
virus to stimulate the immune system. Like the Oxford vaccine, the Novavax
vaccine can be stored at regular fridge temperature – which means it can be
distributed more easily.
In the South African part of the trial, where
most of the cases were the South African variant of the virus, the vaccine was
60% effective among those without HIV.
Johnson & Johnson: The
Janssen vaccine, from American company Johnson & Johnson could become the
sixth vaccine to be approved in the UK. The firm said the vaccine was 85%
effective in preventing severe disease ‘and demonstrated complete protection
against Covid-19-related hospitalisation and death as of day 28.’
worked across multiple variants of coronavirus, including the South
African variant which has been worrying scientists, the firm said. The UK has
secured access to 30 million doses of the Janssen vaccine from Johnson &
The vaccine is estimated to remain stable for
two years at minus 20C and at least three months at 2-8C, which will make the
logistics of rolling the vaccine out easier as it can be stored in a standard
fridge. It could be available at designated vaccination sites across the UK,
alongside existing vaccines.
British regulators have been conducting a
so-called rolling review of the data from Johnson & Johnson. This means
that rather than waiting until the end of the clinical trial to assess the
data, experts from the MHRA have been assessing data on a rolling basis during
the trial and helped speed up the approval process.
Vaccine Tests to date:
Roberta Cava has written 52 books – 44 are
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