GlaxoSmithKline, the world's largest vaccine maker, has laid out plans to produce 1 billion doses of vaccine efficacy boosters for Covid-19 shots next year.

This comes as the race to develop a successful solution to the coronavirus crisis heats up. 

The British pharmaceutical firm said it was in talks with governments to back the manufacturing expansion of the boosters, or adjuvants, that would help to scale up production of future vaccines for Covid-19.

The adjuvant could be a critical ingredient in at least seven experimental vaccines against the new coronavirus currently being developed around the world.

This includes one by Sanofi, with whom GSK signed a collaboration deal in April. 

Adjuvants, a key component of the traditional vaccination approach, have been shown to create stronger and longer-lasting immunity against infections and allow for lower dosing of the protein in a vaccine, making way for higher-volume production. 

GSK would not disclose the programme's costs, saying only that production would take place at sites in Europe and North America and that it would reinvest any profit into coronavirus research and preparation for future pandemics. 

The company is one of the many global players working on projects to counter the respiratory illness that currently that has no treatment and has killed about 350,000 people. 

"We believe that more than one vaccine will be needed to address this global pandemic and we are working with partners around the world to do so," GSK's Global Vaccines President Roger Connor. 

As well as its collaboration with Sanofi, GSK has contributed the adjuvant to alliances involving Chinese biotech firms Clover Biopharmaceuticals and Xiamen Innovax, as well as the University of Queensland, Australia. 

Experts have predicted that a successful vaccine will take more than a year to develop.

Companies and governments are pouring money into dozens of programmes as their best hope of allowing an escape from lockdowns and getting economies expanding again. 

While more than 100 vaccine candidates are being trialled, according to the World Health Organization only ten have moved to testing in humans, a stage where they are investigated for safety and efficacy, and at which most vaccines fail. 

Other promising vaccine approaches do without adjuvants. These include the use of so-called mRNA, pursued by Moderna and Biontech, where genetic code is injected into the body to instruct human cells to make virus-like proteins that trigger an immune response. 

AstraZeneca and Oxford University's viral vector approach, where harmless viruses instruct human cells to make virus-like proteins, also needs no adjuvants. 

The US last week secured almost a third of the first 1 billion doses planned for AstraZeneca's experimental Covid-19 vaccine by pledging up to $1.2 billion. 

GSK said today that making its adjuvant available to the world's poorest countries will be a key part of its efforts.

The company also said today that its previous flu pandemic vaccine, which used some of the same ingredients as Covid-19 vaccines currently under development, was not linked to a rise in cases of the sleep disorder narcolepsy. 

A spokesman for GSK said the "science has moved on" since concerns were raised about links between narcolepsy and its H1N1 vaccine, called Pandemrix, which was developed during the flu pandemic 10 years ago. 

He said evidence now suggests the link is to the H1N1 flu virus itself, not the vaccine. 

Previous studies in several countries, including Britain, Finland, Sweden and Ireland, where GSK's Pandemrix vaccine was used in the 2009/2010 flu pandemic, had suggested its use was linked to a significant rise in cases of narcolepsy in children. 

In a statement to Reuters, the company said available scientific data suggest that "the rare occurrence of narcolepsy during the 2009/10 flu pandemic was triggered by the body confusing a protein in the wild type H1N1 flu virus with a human protein relevant in regulating the sleep cycle." 

It said studies also showed spikes in cases of narcolepsy in unvaccinated populations during that period. 

"Because it is believed that this rare occurrence was specific to the wild type H1N1 flu virus, it is highly unlikely that there would be any implications for a future Covid-19 vaccine," GSK said. 

Narcolepsy is an incurable, lifelong disorder that disrupts normal sleep-wake cycles and causes severe nightmares and daytime sleep attacks that can strike at any time.