Pfizer said in a statement that there are no data to show that “a single dose of the coronavirus vaccine would provide protection from infection after 21 days”.
Why it matters: The UK announced on Wednesday that it would give its vaccination strategy “the required two doses in the shortest time possible, rather than giving as many people as their first dose to at-risk groups”. Some Canadian provinces are doing the same.
- Pfizer confirmed in response that although some protection begins 12 days after the first dose, two doses of the vaccine – separated by three weeks – are the only diet that has been proven to be 95% effective in Phase 3 trials.
- “Everyone will still get their second dose and it will be within their first 12 weeks,” the UK government said in a statement. “The second dose completes the course and is important for long-term preservation.”
big picture: Pfizer’s warning arrives in many countries, including the US, arguing how to deploy vaccines rapidly in the most effective way. The US is on pace to fall far below its target of vaccinating 20 million people by 2020, with only 3 million single doses administered as of Wednesday night.