GSK, Korean biotech SK go head-to-head against AstraZeneca's COVID-19 shot with their experimental vaccine

GlaxoSmithKline has been a little late to the COVID vaccine game and stumbled with partner Sanofi on the way, but it’s now hoping to rival and maybe even beat out AstraZeneca’s vaccine as it starts a new test with a new partner.

The experimental shot, GBP510, comes from Korea’s SK Bioscience, and the biotech is using GSK’s adjuvant tech in a new phase 3.

This comes after some broadly positive interim phase 1/2 results that showed those who got the inoculation had “strong neutralizing antibody responses” and a 100% seroconversion rate. “Neutralizing antibody titres were between five and a maximum of eight times higher compared to sera from people recovered from COVID-19,” GSK said in a statement, noting no safety worries.

The phase 3 will, however, be the real test to assess how well the vaccine can stop infections and disease severity and will enroll around 4,000 subjects “from a range of countries.” In an unusual move, it’s in fact assessing how well the vaccine can work by pitting it against AstraZeneca’s authorized shot. AstraZeneca's vaccine, dubbed Vaxzevria, has lower efficacy than its mRNA rivals from Pfizer and Moderna but is one of the vaccines of choice for many countries around the world, as it costs less and requires less stringent storage requirements.

Almost all global cases are now being spurred by the so-called delta variant, which is incredibly contagious and seems to lower the efficacy of some vaccines over time. While existing vaccines appear to put up a strong defense against severe illness, much of the world still has very low vaccination rates as delta spreads, making the need for more vaccines paramount.  

That’s why the idea is for the GSK-SK vaccine to be sent out around the world to fill the current gap in poorer countries via the COVAX initiative, and, the pair hopes, to be as good as, if not better than, AstraZeneca’s shot. Data are slated for next year.

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“While many countries have made good progress with vaccination, there remains a need for accessible and affordable COVID-19 vaccines to ensure equitable access and to protect people across the world,” said Thomas Breuer, M.D., chief global health officer at GSK.

GBP510 is a self-assembled nanoparticle vaccine candidate targeting the receptor-binding domain of the SARS-CoV-2 spike protein and is wedded with GSK’s adjuvant.

GSK, while late to the race, is ramping up its COVID work, having a new and tweaked late-stage trial with Sanofi now on the go, an mRNA vaccine pact with Germany’s CureVac and a COVID treatment approach with Vir.