Pfizer and Biontech announced that the vaccine against COVID-19 they are developing is "90 percent effective," after preliminary analysis of the results of the third phase of clinical trials, which is the last before submitting an application for licensing.

The two companies said in a joint statement that "this effectiveness of the vaccine" was measured by comparing the number of participants who were infected with the emerging coronavirus in the group that received the vaccine and the number of infected people in another group who received a placebo vaccine, "seven days after receiving the second dose" and 28 days after receiving the first dose.