'R' rate hits lowest level in 10 months with herd immunity possible by July UCL scientists believe rate as of Tuesday was 0.65 to 0.86, better than Government's earlier estimate of 0.7 to 1.1 4 February 2021 • 5:31pm The 'R' rate is at its lowest point since April, according to new modelling which suggests coronavirus vaccines are beginning to have an effect. Scientists at University College (UCL) London believe the rate as of Tuesday was 0.65 to 0.86, considerably better than the official Government estimate of 0.7 to 1.1 published last Friday. They use a more complex and nuanced approach to estimate the current real-world rate of infection rather than looking back roughly two weeks, as Sage does.