AT LEAST 30 million people have had one dose of the coronavirus vaccine, but how important is the Moderna jab to the UK's rollout?

According to The Mail on Sunday, the first 500,000 doses of the Moderna vaccine are expected to arrive imminently - boosting the rollout further.

It is hoped the jab, made by the American company Moderna, will ease pressure on the supply of vaccines for the under-50s, who have been warned their immunisations could be delayed.

Health Secretary Matt Hancock told MPs the vaccine supply in April would be tighter following delays in the delivery of the Oxford/AstraZeneca jab produced by the Serum Institute of India.

He stressed retesting a batch of 1.7 million doses would also impact the supply.

So, how will the Moderna vaccine help Britain's biggest immunisation programme in history and how effective is it against the deadly bug?

How effective is the Moderna vaccine?

The final results of trials confirmed the two-dose jab has a 94.1 per cent efficacy.

No one immunised as part of the 30,000-participant trial developed severe Covid-19, according to the company.

Importantly, the Moderna vaccine doesn't have to be kept at a very cold temperature like Pfizer's.

The US jab can be stored at around minus 20 degrees for around 30 days before it expires.

Pfizer's must be kept at around minus 75 degrees and has a shelf-life of five days.

How does the Moderna vaccine work?

The UK has ordered 17 million doses from Moderna and was the third to be approved by the UK regulator, the Medicines and Healthcare products Regulatory Agency (MHRA).

It was given the green light for use in January, but the Government was told supplies would not be available until the spring.

Similar to the Pfizer/BioNTech shot, the American vaccine uses new mRNA technology that introduces genetic material containing the instructions to make the coronavirus’ spike protein into the body to prompt an immune response.

Moderna side effects - does the jab have any?

For patients receiving the Moderna vaccine, side effects are more common after the second dose.

The most reported side effects may include pain at the injection site, fatigue, headache, muscular and joint pains.

Other side effects may also include a fever, sickness, dizziness and flu-like symptoms.

These are all similar to the other available jabs.

People should remember side effects are usually a sign that the immune system is working.

And of course some people hardly experience any other effects at all.

Where is the Moderna vaccine made?

Most of the jabs developed by the US biotech company are produced at its base in Cambridge, Massachusetts.

The vaccines are sent to other centres to be filled and finished, which are in Catalent's biologics facility in Bloomington, Indiana, and Baxter's site, also in Bloomington, Indiana.

There are also agreements with several manufacturing sites in Europe.

Lonza biotech company, which has sites based in America and Switzerland, is helping Moderna supply vaccines outside of the US.

Under a ten-year plan, Lonza should create more production suites allowing up to one billion doses a year to be produced.

How will Moderna jab impact the UK's immunisation programme?

Although AstraZeneca is the biggest supplier for UK, additional vaccines could help keep the rollout on track.

Britain has ordered more than 400 million doses of seven different vaccines, including 100m from AstraZeneca and 40m from Pfizer.

Despite concerns over supplies, the Government has pledged it will be able to offer second doses within 12 weeks, according to culture secretary Oliver Dowden, who appeared on the BBC’s Andrew Marr Show on Sunday (March 28).

He added the Government is confident it can immunise all adults by the end of July.