Covid-19: Vaccine success drives England's lockdown exit

Siren study - The Pfizer and BioNTech covid-19 vaccine is at least 70% effective against symptomatic and asymptomatic infection 21 days after the first dose and at least 85% seven days after the second dose, shows a UK study of healthcare workers. The Siren study previously investigated the effect of prior infection on protection against reinfection but has now been amended to investigate vaccine effectiveness. The first results following this update have looked at the eight weeks after the first Pfizer-BioNTech vaccine dose.