Since the start of the pandemic, scientists around the world have been racing to develop a jab that prevents Covid-19.
In December, the Pfizer/BioNTech coronavirus vaccine beat its rivals to be the first to be approved for use in the UK, whilst in Australia, the TGA approved the Pfizer/BioNTech vaccine on 25 January 2021.
The Oxford/AstraZeneca vaccine is already in circulation and it was approved by the TGA on 16 February 2021, whist the Novavax vaccine in Australia which has placed an order for 51 million doses after the last AstraZeneca vaccine blow, however it is still waiting for TGA approval.
It is unclear why the government has placed so much trust in the AstraZeneca vaccine, which is produced locally by CSL and no other vaccines such as Moderna and Johnson & Johnson which is the world’s first single-shot Covid vaccine were taken into consideration to be also included into the plan.
So, let us look at what are the differences between the vaccines according to a report by the Evening Standard.
Trials have shown the Pfizer/BioNtech vaccine to be more than 90 per cent 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 diseases.
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.
The vaccine developed by the University of Oxford and pharmaceutical giant AstraZeneca was approved by the TGA on 16 February.
The Oxford jab is not an mRNA vaccine. Instead, it uses a harmless weakened version of a virus that causes the common cold in chimpanzees.
The EMA and the MHRA have both carried out reviews into reports of rare blood clots in people who have had the AstraZeneca vaccine.
Some European countries restricted the vaccine use in younger people following reports of low platelet counts and cerebral venous sinus thrombosis (CVST), a specific type of clot that prevents blood from draining from the brain.
On April 7, the UK’s medicine regulator said that people under-30 should be offered an alternative vaccine. However, experts said the risks of not having an AstraZeneca jab far outweighed any risk of having one.
Professor Calum Semple said he was “not worried one little bit” about headlines around the vaccine. The Sage scientist told LBC: “I’m 53, my risk of death from Covid is about one in 13,000. For me it’s a no-brainer, I need to have the vaccine.”
Oxford data indicates the vaccine has 62 per cent 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 per cent.
The combined analysis from both dosing regimes resulted in an average efficacy of 70.4 per cent.
In separate research, results showed the jab offers 76 per cent protection up to three months after the first dose and could reduce transmission by 67 per cent.
However, a study of around 2,000 people has shown the jab 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 jab worked against severe disease.
Novavax, the third Covid-19 vaccine that could be approved for use in Australia within weeks, as late-stage trials suggested it was 89 per cent effective in preventing coronavirus.
The jab is the first to show in trials that it is effective against the new virus variant found in the UK.
Australia has placed an order for 51 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 per cent 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 per cent were older than 65, Novavax said.
The vaccine will now be assessed by the TGA for approval of administration in Australia according to Health Minister Greg Hunt and could be given out in the “third quarter” of this year.
Pfizer and Moderna vaccines rely on technology that has not been used in previous vaccines, but the Novavax jab 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 jab can be stored at regular fridge temperature – which means it can be distributed more easily.
Johnson & Johnson
The Janssen jab, from American company Johnson & Johnson has not even been taken into consideration by the Australian government.
The firm said the jab was 85 per cent effective in preventing severe disease “and demonstrated complete protection against Covid-19-related hospitalisation and death as of day 28”.
The jab worked across multiple variants of coronavirus, including the South African variant which has been worrying scientists, the firm said.
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 jab out easier as it can be stored in a standard fridge.
The Moderna vaccine which also has not been considered by the Australian government works in a very similar way to the jab 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 response.
Moderna’s vaccine does not require the same ultracold storage as Pfizer’s and can remain stable at normal fridge temperature for 30 days.
The phase three results suggested vaccine efficacy against the disease was 94.1%, and vaccine efficacy against severe Covid-19 was 100 per cent.
More than 30,000 people in the US took part in the trial, from a wide range of age groups and ethnic backgrounds.
Two doses were given 28 days apart so researchers could evaluate the safety and any reaction to the vaccine.
The analysis was based on 196 cases, of which 185 cases of Covid-19 were observed in the placebo group versus 11 cases observed in the active vaccine group.
Moderna also released data relating to severe cases. All 30 severe cases occurred in the placebo group and none in the group which had received the vaccine, known as mRNA-1273.
Edited By Joe Cusmano