People did not know whether they received the vaccine or the dummy injections.Įfficacy was calculated in around 28,000 people from 18 to 94 years of age who had no sign of previous infection. Half received the vaccine and half were given dummy injections. The trial involved around 30,000 people in total. A very large clinical trial showed that Spikevax, given as a two-dose regimen, was effective at preventing COVID‑19 in people from 18 years of age.
