The news this week that the Pfizer/BioNTech Covid-19 vaccine was effective on more than 90% of trial recipients is of huge importance.
The efficacy is significantly higher than hoped for and so far there appear to be no safety concerns.
The Guardian's health editor, Sarah Boseley, explains that, while this is a major breakthrough, there are still several hurdles to overcome, and restrictions, such as wearing masks, social distancing and remote working, must remain in place for the time being.
