Prime Minister Boris Johnson faces a “very difficult” call on whether to drop restrictions on June 21 given the “more negative direction” of the data, according to a leading expert.
Professor Neil Ferguson, whose modelling was instrumental to the UK locking down in March 2020, said a “cautious” approach is needed as the Government balances the potential risks against a desire for normality.
The full effect of easing some restrictions on May 17, such as indoor mixing in pubs, is yet to be understood and further data is required, Prof Ferguson added.
For the Government, Communities Secretary Robert Jenrick said there is “nothing at the moment that suggests that we won’t be able to move forward” with the next stage of lifting restrictions on June 21.
Mr Johnson has come under pressure to move ahead with the June 21 unlocking – dubbed “freedom day” by some – given the huge uptake of Covid-19 vaccines in recent months.
But questions remain over the impact of the so-called Indian variant of Covid, also known as the Delta variant, on hospital admissions and deaths.
Prof Ferguson, from Imperial College London, said the variant is anywhere between 30% and 100% more transmissible than the previously dominant Kent variant, also known as Alpha.
He told BBC Radio 4’s Today programme: “We’re certainly getting more data. Unfortunately, I mean, the news is not as positive as I would like on any respect about the Delta variant.
“The best estimate at the moment is this variant may be 60% more transmissible than the Alpha variant.
“There’s some uncertainty around that depending on assumption and how you analyse the data – between about 30% and maybe even up to 100% more transmissible.”
Prof Ferguson said 60% is “a good central estimate” at the moment and noted that most people in hospital with the virus have not had a vaccination.
He added that data is still awaited on how much the Delta variant can evade the immunity which protects people against being admitted to hospital.