Pfizer and BioNTech have upgraded their release from last week to say that their vaccine has since proven to be 95% effective against COVID-19 after an initial 90% positive rate.
They have released updated results from their final-stage clinical trial with more detailed information.
The findings are based on 170 cases of COVID-19, with 162 of those illnesses happening among people who received a placebo.
Pfizer said the vaccine was similarly effective in older people and in people of different races and ethnicities.
Moderna said on Monday that its shot appeared to be 94.5% effective against COVID-19, based on a preliminary analysis of its final trial.
Pfizer’s results also suggest the shot helps prevent severe disease, with the study tallying 10 cases of severe COVID-19. Nine of those cases occurred in the placebo group.
Pfizer said that the most common severe side effect was fatigue, with 3.8% of participants registering levels high enough to prevent daily activity.
2% of people also had severe headaches. Pfizer said most side effects resolved shortly after vaccination.
Participants in Pfizer’s trial appeared to report fewer severe side effects than volunteers who got Moderna’s shot; 9.7% of those who got the Moderna shot reported severe fatigue, and people also reported aches and pains and headaches as well.