COVID-19 Vaccines: How Do The Moderna, Pfizer And Oxford Coronavirus Jab Candidates Compare?

Three vaccines set for use in the UK have all reported they are around 90% effective in late stage trials.

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The University of Oxford/AstraZeneca vaccine announced its phase three results on 23 November.

It was the final of the three, with the Pfizer/BioNTech - which is now being rolled out in the UK - the first to announce its results, followed a week later by Moderna, but that vaccine has yet to be approved.

The Oxford vaccine works like a traditional inoculation where a spike protein of the virus is injected which the immune system builds up a response to if the real virus enters the body.

Both the Pfizer and Moderna jabs use technology known as mRNA, which introduces into the body a messenger sequence that contains the genetic instructions for the vaccinated person's own cells to produce the antigens and generate an immune response.

mRNA technology has not been used before in vaccines, which brings both solutions and problems.

All of the vaccines require two doses, but the Joint Committee on Vaccination and Immunisation which advises the government said the priority with the AstraZeneca vaccine was to get as many at-risk people as possible a first jab. A second dose to complete the course will be given within 12 weeks.

Final data from the Pfizer vaccine found it offers 95% protection against the virus after two doses.

It also proved 94% effective among adults over the age of 65 - who are generally more vulnerable.

The first dose provided 52% protection after 12 days.

Moderna's results indicate 94.5% effectiveness but it said the trials are ongoing and the final number could change.

The Oxford trial found with two doses its vaccine was 62% effective, but when people were given a half dose followed by a full dose at least a month later its efficacy reportedly rose to 90%.

Some questioned these results - including the UK medicines regulator, who reviewed the data and recommended that two full doses should be administered.

The agency concluded that the Oxford vaccine was up to 80% effective when the second dose was delayed by three months.

The jab already provides 70% protection 22 days after the first dose, according to the UK's Joint Committee of Vaccinations and Immunisations (JCVI).

The second dose for both the Pfizer and Oxford vaccines can be taken up to 12 weeks after the first.

When it was initially approved, the UK medicines regulator said the second dose of the Pfizer vaccine should be administered 21 days after the first - but changed this to a longer interval of between 21 days and 12 weeks.

For the Oxford vaccine, the second dose should be taken between four and 12 weeks after the first.

Professor Wei Shen Lim, chair of the Joint Committee of Vaccinations and Immunisations, said delaying the second dose would allow the NHS to prioritise the delivery of the first dose to as many people as possible.

Those who are pregnant or breastfeeding can be take any of the vaccines approved in the UK, but a discussion with a doctor about the risks and benefits is recommended.

Anyone with an allergy to a specific ingredient in the Pfizer or Oxford vaccines should not receive the jabs.

People with other types of allergies can now safely take the vaccines, according to the UK medicines regulator, who has looked at evidence from the hundreds of thousands of people inoculated so far.

One of the main differences between the vaccines is how they need to be stored.

The Moderna vaccine is much easier to distribute than the Pfizer jab, around which there are concerns, but the Oxford one is the easiest.

During shipment and storage, the Pfizer vaccine must be kept at around -70C (-100F) to maintain optimal efficacy and it also has to be mixed with another liquid before it can be administered.

Pfizer has developed its own packaging to keep doses cold with dry ice so they can be stored for 10 days without specialised freezers, but doses still have to be flown from Belgium then sent to vaccination centres in trucks with thermo sensors and GPS trackers.

The Moderna vaccine has been shown to last for up to 30 days in household fridges, at room temperature for up to 12 hours, and remains stable at -20C - equal to most household or medical freezers - for up to six months.

The company claims mRNA-1273 can be distributed using widely available vaccine delivery and storage infrastructure - with no dilution required prior to vaccination.

Like most other vaccines, the Oxford one will need to be sent to vaccination centres in refrigerated vans or cool boxes and stored in a special vaccine fridge between 2C to 8C and protected from light.

Each vaccine's price tags varies widely, although this will be paid for by the government so will be free for those using the NHS.

The Moderna vaccine is very expensive. It was pitched for $38 (£28) a dose during the summer - much higher than Pfizer, at $20 (£15).

The Oxford/AstraZeneca vaccine will be much cheaper, with the company saying it will cost the government "the same as a cup of coffee", with Sky News understanding that will be a little under £3 per dose, with two doses needed.

AstraZeneca said it will not sell it for a profit so it is available to all countries, no matter the size of their economy.

Moderna - a commercial company - has an interest in making profits, while the researchers for Pfizer made sure it will be made not-for-profit as long as the pandemic continues.

Dr Zoltan Kis, research associate at the Future Vaccine Manufacturing Hub, Imperial College London, said the Moderna vaccine's higher mRNA amount per dose (100 micrograms) compared with Pfizer's (30 micrograms) meant the latter could be produced in higher numbers and at lower cost.

He added that transport issues with Pfizer may counteract that initial advantage, but pointed to the higher temperature at which the Moderna candidate could be stored.

"Therefore, once approved by the regulatory authorities, Moderna's COVID-19 vaccine can be distributed substantially easier and at lower costs compared to the BioNTech/Pfizer vaccine," he said.

The UK government has secured around 40 million doses of the Pfizer vaccine - enough for 20 million people or about a third of the UK population.

It expects 10 million of these doses to arrive before the end of this year, with those chosen to get the jab receiving two doses, 21 days to 12 weeks apart.

The UK has ordered five million doses of the Moderna vaccine, to be delivered by spring. Health Secretary Matt Hancock said this candidate would not be available anywhere in Europe until then.

The government has reserved 100 million doses of the Oxford vaccine, which it has helped fund.

Moderna's first target is the US market since it has been developed with the help of the federally funded National Institutes of Health and the US Department of Health and Human Services, so could be even more expensive for the UK.

It has also received $2.4bn (£1.8bn) funding from the US government and plans to have 20 million doses available for use in the US by the end of the year - meaning other countries must form an orderly queue.

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