GlaxoSmithKline is in the running to bring a new Covid-19 vaccine on to the market by the year end, thanks to positive results from early trials that will allow the formula to enter into late-stage studies within weeks.
The news will offer some relief for GSK as it plays catchup with rivals, and to its chief executive, Emma Walmsley, who has come under pressure since activist investor Elliott Management took a sizeable stake in the company in April.
The vaccine, created with its French partner Sanofi, was originally expected to gain regulatory approval in the first half of 2021, but was delayed in December after it failed to produce a strong immune response in older people.
GSK said on Monday that interim results from a phase 2 trial showed a "strong neutralising antibody response" in all adult age groups, and raised no safety concerns, clearing the way to move to phase 3.
"We believe that this vaccine candidate can make a significant contribution to the ongoing fight against Covid-19 and will move to phase 3 as soon as possible to meet our goal of making it available before the end of the year," Roger Connor, the president of GSK's vaccines arm, said.
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The vaccine uses similar technology deployed in Sanofi's seasonal flu vaccine, and will be used alongside a so-called adjuvant created by GSK, which will act as a booster to the jab.
The phase 3 trial is expected to start in the coming weeks and involve 35,000 adults from a wide range of countries. It will also assess the efficacy of two vaccine formulas against variants which first emerged in Wuhan (D614) and South Africa (B.1.351). The pharmaceuticals firm said it hopes to gain regulatory approval for the vaccine in the fourth quarter of the year.
"Our phase 2 data confirm the potential of this vaccine to play a role in addressing this ongoing global public health crisis, as we know multiple vaccines will be needed, especially as variants continue to emerge and the need for effective and booster vaccines, which can be stored at normal temperatures, increases," said Thomas Triomphe, executive vice-president and head of Sanofi Pasteur, the company's vaccine unit.
The UK had pre-ordered 60m doses of the GSK/Sanofi vaccine as of December.
The phase 3 trial announcement could give GSK more confidence to push back against American hedge fund Elliott Management.
The activist investor, which is known for waging aggressive campaigns for change at companies including BHP and Premier Inn owner Whitbread, took a multibillion-pound stake in the company last month. However, Elliott's intentions at GSK are still unclear.
GSK shares were down 0.3% on Monday at £13.66 each.