The Pfizer-BioNTech vaccine provides protection which lasts for at least six months after the second dose, the companies said Thursday, noting that the vaccine is over 91% effective for the first six months.
They also said the vaccine is fully effective against the South African variant, B.1.351.
The new findings also showed that among the 12,000 volunteers who are at least six months after their second dose, there were no serious safety concerns.
In a joint statement, Pfizer and BioNTech said: "The vaccine was 100% effective against severe disease as defined by the U.S. Centers for Disease Control and Prevention (CDC), and 95.3% effective against severe COVID-19 as defined by the U.S. Food and Drug Administration (FDA)."
It is expected that the new findings will allow Pfizer-BioNTech to request full approval from the US Food and Drug Administration.
Last month, a study showed that though the Pfizer-BioNTech vaccine is effective against the South African variant, it is less effective than against the other variants.