A new COVID vaccine offers 100 percent efficacy against severe disease

Pharmaceutical giant GlaxoSmithKline's (GSK) partnership with Sanofi has yielded a vaccine that prevents COVID-19 infection-related severe disease and hospitalizations, the company claimed in a press release.

Since the pandemic broke out over two years ago, companies and research institutes have adopted different approaches to fighting the virus. While companies like Pfizer used mRNA to mimic the viral structure, AstraZeneca used genetic engineering to modify a chimpanzee virus to behave like one that causes COVID but without its lethality. The partnership of GSK and Sanofi, however, relied on a tried and tested approach for its vaccine, the protein subunit.

What are Subunit Vaccines?

In this approach, harmless protein fragments from the virus are used to train the body's immune system so that it can launch an appropriate response when the actual virus arrives. These protein fragments are synthesized in other organisms such as yeast or bacteria and then harvested and purified being mixed with an adjuvant that can trigger an immune response when injected into the host.

The technique, although more time-consuming and expensive than the mRNA -based approach, has been tested and used widely, such as the hepatitis-B vaccine or the pertussis vaccine. Additionally, the vaccine can be stored at regular refrigerator temperatures, avoiding the need for ultracold storage and making it easier to transport the vaccine to even the remote corners of the planet.

During initial trials, the vaccine did not evoke a robust immune response in older adults, CNN reported. So, the companies went a step back, reformulated the vaccine, and began trials again. This set them back by many months and Phase 3 trials could only begin in May 2021.

Promising results

The companies have now released preliminary data from these trials that were conducted in over 10,000 individuals at various sites in Africa, Asia, and Latin America, in addition to those in the U.S.

According to the press release, the two-dose regimen of the vaccine showed 100 percent efficacy in preventing severe COVID-19 disease including hospitalizations while being 75 percent effective in preventing moderate to severe disease.  

The vaccine was also able to prevent COVID-19-like symptoms in about 58 percent of cases. While this might sound like a drop when compared to the numbers other vaccine manufacturers had shared when their vaccines were being trialed, GSK-Sanofi pointed out the prevalence of multiple variants in the community while the study was being conducted. 

"No other global Phase 3 efficacy study has been undertaken during this period with so many variants of concern, including Omicron, and these efficacy data are similar to the recent clinical data from authorized vaccines," said Thomas Triomphe,  Executive Vice President, Sanofi Vaccines, in the press release. 

Aimed as a booster dose

In addition to being used as a booster after its own two-dose regime, the companies have also trialed the vaccine as a booster, following vaccination with Pfizer or AstraZeneca's vaccine.

Neutralizing antibodies were seen to have increased by 18 to 30-fold in individuals who received the previous vaccine from a different platform. The press release claimed that the antibody levels were 84 to 153-fold higher in individuals who had received GSK-Sanofi's protein subunit vaccines as their previous dose.

Given that large parts of the population in the U.S. and Europe have already completed their initial vaccinations, GSK-Sanofi is aiming for this vaccine to be approved as a booster in these areas and will submit their applications for regulatory approvals soon. 

Detailed data from the trials will also be published later this year, the press release said.