This is interesting, though a bit dry....
www.bbc.com/future/article/20210114-covid-19-how-effective-is-a-single-vaccine-dose
An excerpt as a taster...
"Pfizer....
The second estimate comes from the UK's Vaccine Committee, the JCVI, who decided to calculate the efficacy of the vaccine differently. Instead of using all the data on the number of infections, including from days when the first dose hadn't yet started to work, they only looked at days 15-21. Using this method, the efficacy of the vaccine jumps up to 89%, because it's not being diluted by the relatively high number of infections before the vaccine begins to have an effect. Taking things even further and only looking at the first seven days after the second dose (days 21-28) – because the second dose might not have kicked in yet by then – it's 92%.
However, these calculations are controversial.
|