Is 12 weeks between Covid jabs too long? | David Spiegelhalter and Anthony Masters
Behind the numbers: there are good reasons to believe the UK’s vaccination experiment will work
The UK has a controversial policy of giving second doses of coronavirus vaccine 12 weeks after the first dose, rather than the three-week gap used in other countries. What is the reasoning behind what the Washington Post described as “one big, high-stakes science experiment”?
First, since there are limited doses of vaccine, this strategy means protecting more people, faster. This is an optimisation problem against supply constraints, time and a deadly virus. Modelling showed that, provided the first dose delivered reasonable efficacy, then most lives would be saved by lengthening the gap. By 17 February, there had been about 17 million vaccinations in the UK, with more than 16 million people having had a first dose. If a three-week gap had been used, only about 10 million would have had any vaccine.