GlaxoSmithKline (GSK.L) and Sanofi (SNY) reported strong results in COVID-19 vaccine trials on Monday morning, saying the jab had "triggered strong neutralising antibody responses in all adult age groups."
In an update it said it had found a high immune response after a single dose in patients with prior infection, showing strong booster potential.
"Overall, the vaccine candidate elicited strong neutralising antibody levels that were comparable to those generated by natural infection, with higher levels observed in younger adults (18 to 59 years old)," it said.
Phase 3 trials are expected to start in the coming weeks.
The phase 3 trial is expected to enrol more than 35,000 adult participants from a broad range of countries and will assess the efficacy of two vaccine formulations including the D614 (Wuhan) and B.1.351 (South African) variants.
GSK is a FTSE 100 (^FTSE) drugs giant worth about £69bn ($97bn) and employing 94,000 people.
Despite its size, it has been something of a laggard in the race to produce a coronavirus vaccine, with several other candidates moving to mass-production and worldwide rollout first, including Pfizer (PFE), the Oxford-AstraZeneca (AZN.L) effort and Moderna (MRNA).
GSK stock fell around 0.4% in early trade in London on Monday, in line with the rest of the FTSE 100 index.
“The UK continues to see a very smooth and successful rollout of vaccines, but other countries are still playing catch-up or are experiencing supply shortages," said Russ Mould, investment director at AJ Bell.
"That’s why it could be better late than never for GlaxoSmithKline which has reported encouraging phase 2 results from its joint vaccine candidate with Sanofi.
“The more vaccines the better, as that would in theory increase the chance for countries around the world to have a fighting chance of tackling COVID and start living lives normally again," Mould continues, noting that the next stage trials could still put a spanner in the works.
GSK recently experienced top-level anxiety in its ranks, with 20 shareholders backing the company amid concerns US activist hedge fund Elliott Management was preparing for a shakeup.
Institutional shareholders contacted Sir Jonathan Symonds, GSK's chairman to back up the board's current strategy.
The rumblings from Elliott Management came amid apparent discontent from other large shareholders.
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