Covid deaths are likely to rise to 200 a day and hospitalisations will "reach at least 1,000 per day" following the easing of restrictions on July 19, the Government’s scientific advisers have warned.
At the peak of the winter wave, more than 4,200 people in the UK were admitted to hospital every day, and deaths surged past 1,200 a day.
But a senior source said that as the UK continues to unlock and get vaccinated, Covid-19 figures will begin to resemble those of the flu, with around 20,000 deaths in a bad winter.
Documents from the Scientific Advisory Group for Emergencies (Sage) released on Monday reveal modelling from experts at Imperial College London, Warwick University and the London School of Hygiene and Medicine.
Scientists making the models assumed there would be no "big bang" of people abandoning face masks and social distancing.
Instead, Sage predicts that people will gradually ease their way back to increased social activity over several months and that people will maintain some mitigation behaviors – such as mask wearing and avoiding high-risk indoor events – on their own accord.
The newly released Sage documents also reveal that the speed with which society returns to pre-pandemic levels post-July 19 – the fourth and final step in the roadmap out of lockdown – will have a huge impact on the number of cases, hospital admissions and deaths in the summer.
“The number of hospital admissions likely to occur in this [summer] wave is highly uncertain but is likely to reach at least 1,000 per day, depending on the speed of changes following step 4,” the Sage documents say.
“It is almost certain that the peak in deaths will be well below the levels seen in January 2021 due to the impact of vaccination (assuming that no new dominant variant emerges).”
Sources said the models show it is likely between 100 and 200 people will die every day at the peak of the summer wave.
The Government was given access to the documents and data last week following a Sage meeting of the country’s leading experts via Zoom on July 7.
In the documents, the experts said the current R rate is as high as 1.5 and there are up to 42,000 new cases a day.
"The peak of the resurgence will be much lower if the return to pre-pandemic behaviours is gradual, irrespective of legislative decisions (i.e., any changes happen over several months) than if it is rapid, and if more measures to reduce transmission are maintained," the minutes from Sage meeting reveal.
"Maintaining interventions such as more people working from home, the use of masks in crowded indoor spaces, and increasing ventilation, would contribute to transmission reduction and therefore reduce the number of hospitalisations."
Experts reiterate that while vaccines are effective they have not broken the link between cases and hospitalisations, but the relationship has instead been "weakened in our favour".
Young people, who were only recently eligible for the first dose of their vaccine, now account for more infections than the elderly.
Data from the latest Covid-19 Clinical Information Network (CO-CIN) report, which is run by leading academics including Professor Jonathan Van-Tam and Sir Peter Horby, also published on Monday, shows almost 10 per cent of male admissions are in men aged between 40 and 44, the biggest proportion of any age group.
For women, the age group which is the single greatest contributor to hospital admissions is people between 30 and 34 years old.
In a previous edition of the study published in March, the researchers found people over 75s were the most likely to be admitted to hospital. Men aged 75-79 made up around 12 per cent of admissions, compared to just three per cent for men aged 44 to 49.
There is now a four-fold lower risk of hospitalisation compared with previous waves, sources say, and a nine to 10-fold decrease in the possibility of death following infection.