On November 9th, Pfizer and its German partner BioNTech announced results regarding a vaccine with 90% of efficacy. The news offers hope that a new tool to fight the pandemic will be available in the coming months. This announcement is part of a global competition with enormous financial stakes.
In its latest update on November 3rd, the World Health Organization (WHO) lists 47 “vaccine candidates” evaluated in human clinical trials around the world. This number is steadily increasing, with 11 candidates as of mid-June.
Ten are at the most advanced stage, Phase 3, where vaccine efficacy is being measured on a large scale in tens of thousands of volunteers on several continents. These include the U.S. company Moderna, the German-American alliance BioNTech-Pfizer, several Chinese laboratories, a European project led by Oxford University with the British company AstraZeneca, and the Sputnik V vaccine, developed by Russia and its research institute Gamaleïa.
The 37 others are still in phase 1, which is primarily aimed at evaluating the safety of the product, or in phase 2, where the question of efficacy is already being explored. Laboratories have relied on different methods, some already proven in the history of vaccination, others new.
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Several teams are working on conventional types of vaccines that use an already “killed” virus. These are the “inactivated” vaccines, such as those used by China’s Sinovac and Sinopharm. There are also so-called “subunit” vaccines, based on proteins (antigens), which trigger an immune response without using the virus itself.
Other vaccines, known as “viral vector” vaccines, are more innovative. Scientists use another virus as a carrier, which is transformed and adapted to fight Covid-19. This is the technique chosen by Russia and the University of Oxford. They use adenoviruses (a very common family of viruses). Other projects are based on “DNA” or “RNA” vaccines, experimental products using pieces of modified genetic material. This is the case of Moderna and BioNTech-Pfizer.
Pfizer and BioNTech-Pfizer were the first to report interim results from a Phase 3 trial. They showed that their vaccine is 90% effective in preventing infection with the new coronavirus. They have not yet released data from the trial itself, which is still ongoing.
The European Union “has concluded its negotiations” with Pfizer and BioNTech, and will sign a contract to buy up to 300 million doses of their vaccine against Covid-19, announced the European Commissioner for Health, Stella Kyriakides.