Pfizer’s coronavirus vaccine relies on a new, unproven technology. A diagram shows how it differs from other candidates.



a hand holding a large pair of scissors: A syringe carrying a vaccine. Carol Smiljan/NurPhoto via Getty Images


© Carol Smiljan/NurPhoto via Getty Images
A syringe carrying a vaccine. Carol Smiljan/NurPhoto via Getty Images

Pfizer is now leading the coronavirus vaccine race: The company announced Monday that people who received its two shots during the company’s final stage of clinical trials were less likely to develop COVID-19. The results indicate the vaccine is more than 90% effective in preventing the disease. 

Like the other leading vaccine candidates in the US, Pfizer’s shot does not inject the actual virus, SARS-CoV-2, into the body, contrary to popular myth. Instead, the vaccines all rely on a harmless segment of the virus to spur the production of antibodies.

But to stimulate that immune response, different vaccines rely on different technologies. Pfizer’s candidate is an mRNA vaccine, an unproven technology that uses a snippet of the coronavirus’ genome to encourage antibody production. Moderna’s uses the same approach, though no mRNA vaccine has

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SpaceX seeks to fly unproven rocket, put engine issue to rest

SpaceX has not launched a brand-new rocket since June, when it boosted a GPS III satellite for the US Space Force on a Falcon 9 rocket. Since that time the company has launched several commercial missions and its own Starlink satellites on a variety of previously flown rockets, and they were all successful.

However, when the company tried to launch a new Falcon 9 first stage on October 2—this was for yet another GPS satellite, named GPS III-04—the attempt was scrubbed at T-2 seconds. Later, SpaceX’s Hans Koenigsmann explained that two of the rocket’s nine first-stage engines ignited early during the early October launch attempt, and this triggered an automatic abort of the engines.

This problem was eventually traced to a tiny bit of lacquer used during a metal-treatment process that was supposed to be removed before flight but was not. Now the company believes it has addressed the problem,

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