The success of the UK’s early vaccination programme means Britons are now more vulnerable to coronavirus infection, a leading expert has said.
Professor Neil Ferguson, whose modelling persuaded ministers to lock down in March last year, said waning immunity was one of the factors behind the UK's sharp rise in cases.
His comments came as government figures show that coronavirus cases, deaths and hospitalisations are all on the rise in the UK.
Watch: UK does not have much 'headroom' for rising COVID cases
Prof Ferguson, an epidemiologist at Imperial College London, said on Tuesday there are “a number of reasons” why the UK has higher infection levels than its European neighbours.
He told BBC Radio 4’s Today programme: “Partly, we were very successful in getting vaccination rolled out early and we know that gradually immunity wanes over time after you’ve had that second dose, so how early we were means we are a bit more vulnerable.
“Second, we relied more on the AstraZeneca vaccine and, while that protects very well against very severe outcomes of COVID, it protects slightly less well than Pfizer against infection and transmission, particularly in the face of the Delta variant.
“And finally, we just sit behind a few other countries, not dramatically, but we’re no longer in the top rank of European countries in terms of overall vaccination coverage, particularly vaccinating teenagers.
“Overall coverage rates here are considerably lower, for instance, than in Spain, Portugal and Denmark.”
According to the University of Oxford’s research platform, Our World In Data, the UK had 639 COVID-19 cases per million people on Monday, based on a rolling seven-day average, compared to 123 in Denmark, 111 in Germany, 70 in France, 62 in Portugal, 41 in Italy and 34 in Spain.
Most Western European countries have kept more COVID-19 measures in place than the UK, such mandatory masks in public places.
Asked if booster jabs are the answer to waning immunity, Prof Ferguson said: “Absolutely," adding that there was "good data coming through from Israel which shows that, if you’ve had the third booster dose of the vaccine, then you get very high loads, better than even you had after the second dose.
"And so I do think it’s critical we accelerate the booster programme.
"The other thing is, infection rates are highest in teenagers at the moment and most other European countries are ahead of us in vaccinating teenagers and giving them two doses, not just one dose.
“Two doses really are needed to block infection and prevent transmission, so I think that’s the other problem – keep pushing on, getting coverage rates up higher in the teenagers who are driving a lot of this infection.”
Sir David King, who was the government’s chief scientific adviser from 2000 to 2007, said the pace of the COVID booster rollout was going “extremely slowly”.
According to the government coronavirus dashboard, 2.3 million people in England aged 80 and over had received both doses of vaccine as of April 17, so were eligible for a booster dose as of 17 October.
NHS England figures show that 1.3 million people in England in this age range had received a booster dose as of that date.
In addition, 31% of eligible 75- to 79-year-olds and 15% of 70- to 74-year-olds have had a booster so far.
Shadow health secretary John Ashworth called on the government to "ramp up boosters".
He said on Twitter: "The vaccination rollout is stalling. This is no time for ministers to be complacent."
The latest figures from the government’s COVID-19 database show that cases have increased by 16%, deaths by 11% and hospitalisations by almost 7% in the last seven-day period.
On Monday, there were a further 49,156 lab-confirmed COVID-19 cases in the UK – the highest number of daily reported cases since 17 July.
It meant there were 309,013 cases in the last seven days, an increase of 43,079 – or 16.2% – on the previous week.
The number of weekly coronavirus deaths has also increased, up by 89 – or 11.4% – to a tally of 869 for the past seven days.
There were another 45 deaths recorded on Monday, bringing the UK total to 138,629.
According to the latest bulletin from the Office for National Statistics, about one in 12 children aged 11 to 16 had coronavirus in the week up to 9 October, the age group with the highest infection rate in England.
Watch: COVID vaccine rolled out to 12- to 15-year-olds