More than nine in 10 people given the Pfizer or AstraZeneca Covid-19 vaccine develops antibodies after a single dose, a new study suggests.
And nearly every single person develops an antibody response after the second jab, the study implies.
Antibodies help to fight infection and having antibodies in the blood shows that people have either had the infection before or have received a vaccine.
A new study, led by researchers from University College London (UCL), examined levels of antibodies in the blood among more than 8,500 people in England and Wales.
These people had received either the Pfizer/BioNTech or the Oxford/AstraZeneca jab and were an average age of 65.
Researchers found that antibody response rose more quickly among those who had the Pfizer jab.
Two to three weeks after the first dose of the Pfizer jab, 89% of people showed an antibody response compared to 66% of those who received the AstraZeneca vaccine.
At 28 to 34 days after the first dose of either jab, 96% of people had antibodies in their blood.
And a week or more after the second dose of the vaccine, 98-99% of people tested positive for antibodies, according to the study which is yet to be peer-reviewed and published in a scientific journal.
Lead author of the paper, Dr Maddie Shrotri told The Guardian: “This is one of the earliest real-world vaccine studies in the UK and it is fantastic news.
“Over nine out of 10 adults in the UK who had either the Pfizer or AstraZeneca vaccine produced antibodies against the virus within a month of their first shot.
“How well these vaccines work is remarkable, especially given the speed at which they’ve been developed.
“It’s a real feat of science in the face of the most devastating pandemic in a century.”
Across the UK more than 69% of adults have had their first coronavirus jab.
Around 57 million vaccinations have been delivered including 20 million second jabs.