The most effective coronavirus vaccine so far may not be widely available in Britain because US citizens are being given priority.
On Monday, Moderna became the third group to release interim trial results, confirming that its vaccine protects 94.5 per cent of people, making it more successful than the jabs from Pfizer/BioNTech and Russia.
The government said it was in “advanced discussions” with Moderna to ensure access to the new vaccine and the Health Secretary announced five million doses of the vaccine have been ordered for the UK.
But doses will not be available in Britain until Spring 2021 at the earliest, because the company has prioritised the US.
A government source said Moderna had been clear that the US was its main market and availability would be limited.
The government has instead ordered 350 million vaccines from BioNTech/Pfizer, Oxford/AstraZeneca, Novavax, Janssen, GSK/Sanofi Pasteur and Valneva.
British experts hailed the latest vaccine announcement as “tremendously exciting”, saying it suggested that the world would soon have several available jabs.
“First we heard 90 per cent efficacy from Pfizer and BioNTech, then the Russians said 92 per cent and now Moderna says 94.5 per cent,” said Peter Openshaw, Professor of Experimental Medicine at Imperial College London.
“This news from Moderna is tremendously exciting and considerably boosts optimism that we will have a choice of good vaccines in the next few months.
“This announcement adds to the general feeling of optimism about vaccines for Covid-19.”
The Moderna drug is also far easier to distribute because it can be kept in usual freezer conditions of -4 F (-20), whereas Pfizer’s jab needs to be stored and transported in dry ice around -103F (-75C).
However it may prove more costly because it needs 100 micrograms per dose – more than three times more than Pfizer’s.
The Pfizer vaccine is already set to be ten times more expensive than the Oxford/AstraZeneca version so Moderna’s jab could be prohibitively costly.
Both jabs are pricey because they work using a completely new technology. Instead of injecting an inactivated virus into the body, the vaccine carries ‘messenger RNA’ which instructs the body’s cells to build the coronavirus ‘spike protein’ – the little stick on the outside of the virus which allows it to attach to human cells.
Once the body starts producing these proteins, the immune system sees them as foreign, and initiates a T-cell and antibody response, priming it to fight off a real infection.
Moderna has been testing the jab on 30,000 people and interim results show it protected nearly everyone from the virus, including the elderly and vulnerable, who are most at risk. It is the first vaccine so far to be shown to protect older people and prevent serious disease.
This first interim analysis was based on 95 cases, of which 90 cases of Covid-19 were observed in the placebo group versus five cases observed in the mRNA-1273 group.
A secondary study analysed severe cases of Covid-19 and included 11 severe cases. All 11 cases occurred in the placebo group and none in the mRNA-1273 vaccinated group.
Side-effects were mild and short-lived, and included fatigue, muscle pain, joint pain, headache, soreness at the injection site.
“This is a pivotal moment in the development of our Covid-19 vaccine candidate,” said Stéphane Bancel, Chief Executive Officer of Moderna.
“Since early January, we have chased this virus with the intent to protect as many people around the world as possible.”
Moderna said it intends to submit for an Emergency Use Authorisation (EUA) with the US Food and Drug Administration (FDA) in the coming weeks.
Commenting on the results Stephen Evans, Professor of Pharmacoepidemiology, London School of Hygiene & Tropical Medicine, said: “This announcement from Moderna is a further encouragement that vaccines will be found to not only have an acceptable efficacy, but an efficacy that is much greater than we had anticipated.
“This is the first study to report on severe cases and, while uncertainty remains, the finding of no severe cases with the vaccine and 11 cases with placebo is very strong evidence that the vaccine prevents severe as well as mild disease.”