The Covid-19 vaccine jointly developed by Sanofi and GlaxoSmithKline has lagged its peers in clinical development, but the partners pressed on noting that particular features of their shot make it valuable as a vaccination option. With analyses of key clinical data now in hand, the companies said Wednesday that they plan to seek authorizations from regulators.
The Sanofi-GSK vaccine is protein based, comprised of antigen engineered by Sanofi combined with a GlaxoSmithKline adjuvant, an ingredient that boosts the immune response. Those vaccine components have already been used successfully in influenza vaccines, so they are familiar to regulators and clinicians. Another key feature is that the Sanofi-GSK vaccine can be kept at standard refrigerator temperatures, which is an advantage over the ultra-cold storage and distribution requirements of messenger RNA vaccines.
The Phase 3 study enrolled more than 10,000 volunteers, age 18 and older, randomly assigned to receive the Sanofi-GSK vaccine or a placebo. Shots were given 21 days apart at sites in the U.S., Asia, Africa, and Latin America. In this test of the vaccine as the primary vaccination, the companies reported that the two shots led to 100% efficacy against severe Covid-19 disease and hospitalization and 75% efficacy against moderate or severe disease.
Measured against omicron and other variants of concern, the efficacy drops to 57.9%. That lower efficacy is expected, as other vaccines have also shown reduced efficacy against new variants. However, comparisons to the clinical trial efficacy marks posted by the previously authorized vaccines is tricky, as those studies were largely conducted before the emergence of the delta and omicron variants.
Sanofi and GSK have had to overcome clinical trial setbacks. In late 2020, the partners announced a delay in plans for mid-stage testing in order to adjust the vaccine to achieve an improved immune response in the elderly. By the time the partners were able to report preliminary Phase 2 data last May, the Covid vaccines from Pfizer/BioNTech, Moderna, and Johnson & Johnson had already been authorized and were being distributed widely throughout the U.S.
A Deep-dive Into Specialty Pharma
A specialty drug is a class of prescription medications used to treat complex, chronic or rare medical conditions. Although this classification was originally intended to define the treatment of rare, also termed “orphan” diseases, affecting fewer than 200,000 people in the US, more recently, specialty drugs have emerged as the cornerstone of treatment for chronic and complex diseases such as cancer, autoimmune conditions, diabetes, hepatitis C, and HIV/AIDS.
According to the Covid Data Tracker maintained by the Centers for Disease Control and Prevention, about 215 million people in the U.S. are fully vaccinated (two doses of an mRNA vaccine or one dose of the J&J shot), representing 64.8% of the population. The CDC counts 93.2 million people having received booster shots, which represents 43.4% of those who are fully vaccinated.
Given that the components of the Sanofi-GSK vaccine are known and have a track record of safety, the shot may be able to win over some those who have been hesitant about vaccines made with newer technologies. The Sanofi-GSK vaccine may also find a place as a booster. The data reported Wednesday include results from a separate trial that tested the vaccine as a booster for those who had already received a primary vaccination series of an already authorized mRNA or adenovirus vaccine. The companies reported that their vaccine led to an increase in neutralizing antibodies ranging from 18-fold to 30-fold, across vaccine platforms and age groups.
“The Sanofi-GSK vaccine demonstrates a universal ability to boost all platforms and across all ages,” Thomas Triomphe, executive vice president of Sanofi Vaccines, said in a prepared statement. “We also observed robust efficacy of the vaccine as a primary series in today’s challenging epidemiological environment. 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.”
The data for both clinical trials were reported in a news release. Sanofi and GSK said that full data for the studies will be published later this year. In both studies, the companies reported that the vaccine was well tolerated in younger and older adults with no safety concerns. Sanofi and GSK said that they are already in discussions with regulatory bodies, including the FDA and the European Medicines agency, about filing for authorizations.
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