The Delta variant arrived in the UK in early
March and within 14 weeks it accounted for almost all new COVID-19 infections. With a significantly
greater transmissibility than the Alpha variant, which had dominated infections in the UK in the first 4
months of this year, the reproduction number in the UK has risen from 0.74 in early March to 1.49 in late
June. As a consequence, daily new infections have risen from the recent trough of 1,649 on May 3 to the
latest reading of 27,334.
At the current pace, vaccinations are pushing the reproduction
number down by around 0.0098 a day. At this pace, the UK reproduction number will remain above one for
another 50 days.