The approval of the Biontech/Pfizer Covid-19 vaccine for use is just the start of a massive logistical and technical operation to protect the most vulnerable in Wales.

The Medicines and Healthcare products Regulatory Agency (MHRA) approved the American made vaccine today (Wednesday) but the route to people being injected with the new drug will take at least four to five days from here.

Chief pharmaceutical officer for Wales Andrew Evans said there would have to be a “short but necessary delay between the regulator giving approval and it being ready to use in a clinical setting”.

That relates to the instability of the new vaccine, which is a brand new technology that needs to be stored between -70C and -80C before being readied for use.

The first people to get the new drug will be staff and residents in older care settings, seen to be the most vulnerable group, before it’s rolled out to “patient facing healthcare workers” and those aged 80 or over in the next tranche of immunisation.

Planning for rolling out the vaccine has been going on in health boards since June but no one knew which  one would be first out of the blocks.

The Biontech/Pfizer drug is the most difficult to prepare and the scale of the operation was outlined to journalists in a strictly controlled briefing.

Mr Evans revealed that only pharmaceutical wholesalers licensed by th MHRA will be able to distribute the vaccine, as they expect it will need to be transported in its frozen state, possibly on dry ice.

He said: “Even with a following wind, it will be 48 to 72 hours before a vaccine arrives with wholesalers in Wales.

“Then there will be a short period, between 24-36 hours, to take it from wholesalers into clinical settings.”

From there, each vial of the vaccine, which is transported in packs of 195 vials, will need to be thawed then diluted with sodium chloride before being split into five doses ready for use.

Once thawed, the vaccine has a shelf life of around five days, which has made planning the programme particularly challenging.

Experts in Wales will only get the full stability data of the new drug from safety information packs when it arrives in Wales.

“There are a number of factors that need to come together,” he said.

“Everything that can be done to prepare is being done. There will be a short but necessary delay between the regulator giving approval and it being ready to use in a clinical setting.”

The order in which different groups get the vaccine was explained by Richard Roberts from Public Health Wales, who is also co-chair of the Covid-19 Vaccination Programme Board.

It will roll-out in this order:

Staff and residents in older residential care; then

Health care workers and social care workers with a patient facing role or in locations where they are client facing (work is still going on to classify workers), plus people aged 80 years or older; then

People aged 75 years or older; then

People aged 70-74 years; then

People aged 65-69 years; then

Those aged under 65 classified as having “risk conditions”; then;

People aged 60-64; then

People aged 55-59; then

People aged 50-54.

Mr Roberts said they are waiting on advice on where to place those previously asked to shelter because they are “clinically extremely vulnerable” within that list.

Mr Roberts said that will cover 60 per cent of the population and 90 per cent of all groups from which deaths have occurred.

In addition to that, those with occupations that put them at risk of catching the virus will be immunised next, which will cover groups responsible for 99 per cent of all deaths.

Mr Roberts said: “It’s really tremendous excitement to be at a position, only nine months after the WHO declared a pandemic, to be able to consider using not just one Covid vaccine but two very shortly and then a whole range of others.”

The vaccine is 90 per cent effective, according to the manufacturer, and Mr Roberts said modelling had told them 59.1 per cent of the population needs to be immunised for it to be effective at protecting people in Wales.

He said the modelling had informed health officials that around a 75 per cent take-up of the vaccine was expected.

Welsh Government’s Gillian Richardson is also co-chair of the Covid-19 Vaccination Programme Board and she explained some of the planning that has gone into the roll-out.

She said: “We’ve been planning for the first vaccine since June, but we didn’t know which vaccine it would be.

“Health boards have been planning for months and recruiting immunisers to their banks. They’ve really been preparing in earnest.

“We’ve also had military planning support and a couple of planners have been assisting the centre of operation. Each health board also has a military liaison officer.”

She said the vaccine would be treated “like a VIP” and was “getting the same security”.

Health Boards are likely to use a variety of settings to administer the vaccine but the Biontech/Pfizer drug will be difficult to transport, so vaccination centres where people come to it are expected to play a large part in the roll-out.

The next vaccine expected to be approved is the British developed Oxford/Astra Zeneca version.

Transportation of that drug will be much less problematic because it can be stored similarly to other vaccines, which normally need to be refrigerated between 2C and 8C.

It is possible the British vaccine could also be approved before Christmas. That and five other vaccines have won advanced order from the UK Government.