Sanofi and Glaxo say their COVID vaccine shows 100% efficacy against severe disease

Sanofi logo at their headquarters
Sanofi and Glaxo say two doses of their vaccine have 100% efficacy against severe COVID-19 and hospitalizations and 58% efficacy against any symptomatic COVID-19 disease.
(Christophe Ena / Associated Press)
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Sanofi and GlaxoSmithKline, the pharmaceutical giants that stumbled in the race to develop a COVID-19 shot, reported that their vaccine protects against severe disease and hospitalization, and they’ll submit data to regulators for clearance.

The duo said data from a trial shows that two doses of the Sanofi-GSK vaccine have 100% efficacy against severe COVID-19 and hospitalizations and 58% efficacy against any symptomatic COVID-19 disease. They said the safety of the vaccine was favorable too.

Meanwhile, a separate study showed the vaccine could increase neutralizing antibody levels 18- to 30-fold when used as a booster in people who’ve received other types of shots first.


Shares in Sanofi rose as much as 1.7% in Paris on Wednesday, while GSK rose as much as 1.6% in London.

The data should allow the vaccine giants to finally play a big role in the pandemic fight, after repeated development delays allowed nimbler competitors like Moderna and the BioNTech-Pfizer alliance to rush ahead with messenger-RNA (mRNA) products. Those companies, along with AstraZeneca and Johnson & Johnson, steered highly effective products rapidly to market, helping save millions of lives and earning tens of billions of dollars in revenue.

While the Sanofi-Glaxo product appears to be on par with the mRNA shots when it comes to preventing severe disease and hospitalization, the efficacy may trail somewhat in terms of symptomatic disease, Sam Fazeli, an analyst at Bloomberg Intelligence, said in a note.

Experts say it’s unlikely the highly transmissible Omicron variant — or any other variant — will lead us closer to herd immunity against COVID-19.

Feb. 23, 2022

“The vaccine will find a place among people reticent to take mRNA vaccines and in lower-income countries, making for a modest commercial impact on Sanofi and Glaxo,” Fazeli said.

More than 10 billion doses of COVID vaccines have been administered worldwide and demand is now increasingly coming from poorer countries and booster campaigns.

The Sanofi-Glaxo inoculation has some potential advantages over most existing COVID shots. It can be kept at refrigerator temperatures, making it easier to transport and store than the current mRNA shots. The product also relies on recombinant protein technology that Sanofi uses to make flu vaccines and an adjuvant from Glaxo to enhance the immune response.

By now, though, Sanofi and Glaxo are facing a new crop of rivals with Covid shots. Novavax for instance, also has a recombinant-protein product and it’s been cleared in Europe and by the World Health Organization since December.

Sanofi and Glaxo’s candidate endured months of delays after the companies mistakenly gave participants in an early-stage trial lower doses than planned.