A COVID-19 vaccine could be ready for Christmas but with any new inoculation there are questions about how it will be safely administered.
Sky News looks at how a mass vaccination programme could happen and what difficulties could arise.
Which vaccines could be available and by when?
The Pfizer/BioNTech vaccine, which developers announced was 90% effective after stage three trials, is set to be given to the most vulnerable people in the UK before the end of the year.
Forty million doses of the vaccine have been ordered by the British government, with the prime minister saying this will vaccinate one third of the population.
The Moderna vaccine, which is showing nearly 95% protection in early data, will provide five million doses to the UK from next spring if it is successful.
Following the initial results from the first two vaccines, hopes are being raised for the one being developed by Oxford University with AstraZeneca, which the government has reserved 100m doses of.
Sir John Bell, who is leading Oxford's programme, told MPs his team is weeks away from a result and believes there is a "70-80% chance" the vulnerable could be vaccinated by Easter.
How will the vaccine be administered?
Mass vaccine centres will be set up to innoculate people and the government has plans for large and small mobile sites, while GP surgeries and pharmacies will also be used and roving teams of healthcare professionals will visit care homes and people who are housebound.
Pfizer/BioNTech's vaccine will require two doses, three weeks apart.
The Moderna vaccine will also need two doses, but four weeks apart.
Oxford/AstraZeneca's trial is testing whether it can use just one shot but at the moment it will require two doses a month apart.
Will the vaccines definitely be in injection form?
Not necessarily, but most likely for now, said Dr Al Edwards, associate professor in biomedical technology, Reading School of Pharmacy.
Some vaccines are now administered without injections, orally or up the nose.
Polio, cholera, typhoid and rotavirus (for babies) can all be immunised against using drops placed on the tongue.
Children can also get a nasal flu vaccine, where it is sprayed up their nose.
Researchers at Imperial College London are trialling whether their vaccine and the Oxford one can be inhaled through the mouth.
Their hope is by inhaling the inoculation it will "induce a more effective immune response" against the virus as it will directly target the point of infection, the Medical Research Council said.
Pfizer's chief scientist Mikael Dolsten has said his team is looking at making a second generation of its vaccine in powder form so it only needs refrigeration. The powder would then be reconstituted into a liquid before being injected or inhaled.
What are the logistics of getting a vaccine to people?
Dr Edwards said the main issue will not be the physical logistics, but having enough healthcare professionals to administer doses.
He told Sky News: "The bottleneck will be production of doses, and having enough people to administer them is going to be a mad scramble.
"Although this will be bigger, our system in the UK is set up to carry out mass vaccinations, like we do every year for flu - we have teams around the country who organise the logistics of this.
"But, we don't have spare people, GPs are struggling to deliver high-quality day-to-day care and you're asking them to add something more.
"Other healthcare professionals will be needed and people like pharmacists, paramedics and physicians associates are trained to carry out vaccinations, but we're desperate for people to carry out these roles."
The Pfizer vaccine would be the most difficult to get to vaccine centres as it needs to be stored at -70C.
But Pfizer has designed its own packaging to keep doses cold with dry ice so they can be stored for 10 days without specialised freezers that can only be opened twice a day for less than three minutes at a time to maintain the temperature.
Doses would be flown from Belgium then sent to hubs and vaccination centres in trucks with thermo sensors and GPS trackers, then they can be stored in medical fridges for up to five days at 2-8C.
Moderna's vaccine will be flown from Switzerland or Spain and has to be frozen, but only at -20C which is what a standard freezer can be set at.
That will require refrigerated trucks and the vaccine can only be kept in a standard fridge for up to seven days.
Doses of the Oxfor/AstraZenca vaccine will need to be sent to GP surgeries in refrigerated vans or cool boxes and placed straight in a special vaccine fridge between 2C to 8C and protected from light - just as flu and other vaccines are.
What happens if somebody has an adverse reaction to a COVID-19 vaccine?
Dr Edwards said for the majority of people, the worst reaction they will get is a sore arm, like any vaccine.
The psychology of having an injection is also an issue as some people faint at the sight of needles.
"They could bang their head so that's why it's important to have a healthcare professional do the inoculation and keep an eye on them for a few minutes after," he said.
In very rare instances, people can have an anaphylactic reaction where they have an immune reaction to an ingredient in the vaccination.
"You can have an anaphylactic reaction to any type of medicine," Dr Edwards said.
"That's also why it is important to have a healthcare professional there because they can easily treat that.
"However, it is very rare and for the flu vaccine happens just 10 times out of 15 million - the COVID-19 vaccine will likely be no different."
At the moment, none of the COVID-19 vaccines are produced using eggs, unlike most flu vaccines, so there should be no issue for people with egg allergies.
Dr Edwards added that the vaccines are being tested on very large numbers of people for a vaccine trial and they are being very closely mapped.
Adverse effects take a maximum of a few days to develop so the trials would show up anything pretty quickly.
"After the vaccine is approved, the safety data will not stop being watched," he added.
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How much will the vaccines cost?
The government will be paying for the vaccines, but their costs vary a lot.
Both the Pfizer and Moderna vaccines use RNA technology that has never before been used in a vaccine, meaning they will both be very expensive.
For the two Pfizer jabs needed, the US is paying £29.47 while one dose of the Oxford/AstraZeneca vaccine will only cost £2.23 for EU countries and is likely to cost even less for the UK as the government helped fund it.
The Oxford vaccine can be produced much more cheaply because it relies on traditional methods of vaccine production where a spike protein of coronavirus is injected which the immune system builds up a response to if the real virus enters the body.
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2020-11-17 17:59:58Z
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