It comes after a trial of the AstraZeneca vaccine in children was paused while regulators at the Medicines and Healthcare products Regulatory Agency (MHRA) investigate a potential association between the jab and a rare form of blood clot.
Professor Adam Finn, from Bristol University and a member of the JCVI, said it is vital to keep vaccination going.
"We do need to keep the programme going if the plan to open things up and allow things to get back to normal is to proceed without another wave of the pandemic coming through,” he told BBC Breakfast on Wednesday.
"It’s quite a tricky balancing act here, getting the balance right, getting vaccines coming through… getting the risk-benefit right for people coming forward.”
He urged people offered the AstraZeneca vaccine to take it, saying the “risk-benefit is very strongly in favour of receiving the vaccine”.
The European Medicines Agency (EMA) is expected to give an update on Wednesday afternoon.
Prof Finn told BBC Radio 4’s Today programme the reports of clots were being investigated “very seriously” and “very thoroughly”.
He said: “What stands out about them is that we see thrombosis, including thrombosis in the cerebral veins, all the time, but we don’t normally see them in association with a low platelet count – which is a small blood cell which is involved in blood clotting – and so that makes them stand out and makes us think that this is something a little bit different and out of the norm.”
In the last MHRA update, 30 cases of the blood clots and seven deaths were reported in the UK among more than 18.1 million people receiving the jab.
Professor Calum Semple, a member of the Scientific Advisory Group for Emergencies (Sage), said he was “not worried one little bit” about headlines around the AstraZeneca vaccine.
He told LBC radio: “This vaccine is safe. What do I mean by safe? You can look right, look left, look right again, cross a road, it’s safe to cross because you don’t see any cars [but] you can trip, you can stumble.
“Nothing is risk-free, but is the vaccine safe? I would say yes.”