Coronavirus in the UK: Britain could face large Covid wave if lockdown restrictions are lifted too quickly
Professor Steven Riley, a member of the SPI-M modelling group, said that while the rollout of the vaccination programme had been "incredibly successful" it did not mean controls could simply be dropped.
"No vaccine is perfect. We are certainly going to be in the situation where we can allow more infection in the community but there is a limit," he told the BBC Radio Today programme.
"I think scientists are genuinely worried. We don't want to show that it is an excellent but not perfect vaccine by having another large wave in the UK.
"Nearly 20% of the UK population is 65 years old or older. If you do some simple back of the envelope (calculations) for a vaccine that is very good but not perfect, there is the potential for another really substantial wave. That is not where we want to go in the short term.
"If for some reason we were to choose to just pretend it (coronavirus) wasn't here any more, then there is the potential to go back to a wave that is a similar size to the one that we are in now."
Ministers are confident they will meet the target of offering a first dose of the vaccine to all those in the Government's top four priority groups - including all over-70s in the UK - by the deadline of Monday.
However, that has led to renewed demands for a relaxation of the restrictions to allow the economy to open up again.
Former cabinet minister David Davis said they should begin with schools - which are due to reopen in England on March 8 - as part of a "stepwise" winding down of controls.
Treatments for Covid-19 will soon be fast-tracked through the UK's clinical trial system, meaning they could be available on the NHS in months rather than years.
Reporting by PA
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