What to Know About the New COVID Vaccine From Sanofi-GSK

The companies said the vaccine was highly effective in clinical trials. Here's what we know about it now, and when it could be available.

Jessica Rendall Wellness Writer
Jessica is a writer on the Wellness team with a focus on health news. Before CNET, she worked in local journalism covering public health issues, business and music.
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Jessica Rendall
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Last week, Sanofi and GSK (GlaxoSmithKline) announced that their COVID-19 vaccine is highly effective -- as high as 100% against hospitalization, according to the results of a clinical trial shared by the companies. It's also effective as a booster, and Sanofi and GSK said the vaccine will be submitted to the US Food and Drug Administration as well as European regulators for use as a primary COVID-19 vaccine series and a booster. 

As the US Centers for Disease Control and Prevention loosens the mask guidance for the majority of the country, and the Biden administration increases focus on COVID-19 treatment with initiatives like Test to Treat, infection prevention remains an imperative part of the fight against COVID-19. 

Here's what we know about the Sanofi-GSK vaccine -- one of many being developed that researchers hope might add to the world's arsenal. 

Is the Sanofi-GSK vaccine available yet? 

No. The two European companies last week issued a press release with promising results of a Phase 3 clinical trial on its vaccine (to be called Vidprevtyn) and also said they're "in discussion" with regulators at the FDA and in Europe, with plans to submit data for authorization or approval.

In order for a vaccine to become available for use in the US under emergency use authorization, given in public health emergencies like a global pandemic, the FDA must first go over safety and effectiveness data from clinical trials. Right now, there's no timeline for when the Sanofi-GSK vaccine will be reviewed by the FDA. 

Can the vaccine be used as a booster after a different COVID vaccine?

If given authorization/approval, yes. GSK and Sanofi said they plan to submit data on the vaccine as a booster to regulators as well as the primary series.

If the primary series ends up being authorized by the FDA, people may be able to receive the vaccine as a booster dose following a shot of Johnson & Johnson or two shots of Pfizer or Moderna. For booster doses of the three currently available vaccines in the US -- Pfizer, Moderna and Johnson & Johnson -- the FDA has authorized a "mix and match" approach.

Andriy Onufriyenko/Getty Images

How is the Sanofi-GSK vaccine different?

The primary vaccine series is a two-dose vaccine, like Pfizer's and Moderna's. What sets it apart from vaccines available now is that it uses a different technology than the mRNA vaccines (Pfizer's and Moderna's) or viral vector vaccines (Johnson & Johnson's). The Sanofi-GSK vaccine is a protein-based vaccine, which is a common type of vaccine that's been in use for many years for shingles, hepatitis and more

For some people who are hesitant about the mRNA vaccine technology (which doesn't contain any live virus but instead has instructions for our cells on how to build immunity), having a COVID vaccine option that uses technology that's been around for years may offer peace of mind and more choice.

Read more: Here's How Long Your COVID Vaccine Booster Provides Protection 

How effective is the vaccine? Is it really 100% effective?

The companies said that, in a clinical trial, two doses of its vaccine as a primary series offers serious protection: 75% efficacy against moderate or severe disease, nearly 58% against symptomatic COVID-19 and 100% efficacy against hospitalization. 

As The New York Times reported, the number of COVID-19 infections in the trial was small, and the vaccine's efficacy may have been lower in a larger trial. Full results on the vaccine as a primary series and as a booster will be published later this year, Sanofi and GSK said. 

No matter how protective and effective, no vaccine is 100% effective when it starts rolling out to millions and millions of people.

Is the Sanofi-GSK vaccine the only new one being developed?

No. The makers of Novavax, a similar vaccine, submitted data for authorization to the FDA last month. In January, Moderna and Pfizer announced they were working on omicron-specific COVID-19 vaccines. There are also other COVID-19 vaccines in various stages of development around the world.

As Dr. Anthony Fauci alluded to at a press briefing Wednesday, moving forward, public health agencies might put more research efforts towards a universal COVID-19 vaccine that can work against multiple variants, as opposed to focusing on vaccines that are based on earlier strains of the virus. One pan-coronavirus vaccine, developed by scientists with the US Army, is being tested and might have the potential to work against future strains of the coronavirus.

The information contained in this article is for educational and informational purposes only and is not intended as health or medical advice. Always consult a physician or other qualified health provider regarding any questions you may have about a medical condition or health objectives.