"In other words, we don't know whether vaccines will reduce transmission - yet."
The government has admitted it is unsure whether any of the Covid-19 vaccines actually prevent transmission of coronavirus.
Speaking during today's coronavirus press briefing, Professor Jonathan Van-Tam was asked whether people can begin to mix with others after a second vaccine.
He said that, while the vaccines will likely ward off deadly illness and therefore reduce deaths, it is not known whether you will still be contagious.
Van-Tam said: "The magic phrase is transmission. We will know quite quickly within a matter of months the impact of these vaccines on reducing severe illness in the general population.
"I hope we'll be able to say, 'Your chances of severe illness from Covid are very markedly reduced'.
"But right now, we can't say that is synonymous with you not being able to pass the virus onto others.
"In other words, we don't know whether vaccines will reduce transmission - yet."
Van-Tam, who has served as Deputy Chief Medical Officer of England since 2017, said authorities will continue to monitor the situation.
"We will definitely continue looking at that," he said.
"Public Health England have their finger on the pulse on this one through the SIREN study in particular. We'll get a handle, quite soon I hope, on whether these vaccines reduce transmission."
Until then, Van-Tam urged the public not to act recklessly even if you have had the vaccine.
"I can assure you it's very likely you'll be protected from severe illness, but I can't give you the assurance that you won't still pose a hazard to others through transmitting the virus."
Earlier today,
the Oxford-AstraZeneca vaccine was approved for use in the UK.
Health Secretary Matt Hancock has confirmed that the UK now has enough vaccinations to cover the entire population.
"I can now say with confidence we can vaccinate everyone," Hancock confirmed on BBC Breakfast. "We've got enough of this vaccine on order to vaccinate the whole population - 100 million doses. Add that to the 30 million doses of Pfizer and that's enough for two doses for the entire population."
