==Speaking in an All-Party Parliament Group on coronavirus, Prof Barclay said: "What we don't know at the moment is how long does the booster effect last.
"A graph has shown two doses of Pfizer plus a Pfizer boost, there's a definite increase in the number of people who have antibodies.
"But three months after that booster dose you're back down again to only 25 percent of the people having the antibodies.
"We're definitely boosting but there is some doubt over how long the booster will last."==
So on and on then?