96% Of People Develop Covid Antibodies After Just One Shot Of Pfizer Or AstraZeneca Vaccine, U.K. Study Finds

Published 2 years ago
Healthcare professional in protective gloves & workwear holding & organising a tray of COVID-19 vaccine vials

TOPLINE A new U.K. study has found that more than 95% of Britons vaccinated with just one shot of the Pfizer or AstraZeneca vaccine develop Covid-19 antibodies, a figure that rises to almost 100% after the second dose, adding to mounting evidence from the real-world deployment of the vaccines that show they are effective and useful tools in bringing the pandemic under control. 


In a study of more than 8,500 people from England and Wales, who did not have antibodies before their first shot and provided a total of 13,232 antibody samples, 96% developed antibodies 28 to 34 days after receiving their first dose, according to research from University College London (UCL).

The research, which is being prepared for peer review, found this figure to rise to 99% within seven and 14 days of their second shot for recipients of both vaccines, evidence that they provide protection against the coronavirus. 


While those receiving the Pfizer-BioNTech vaccine developed antibodies faster than those receiving the AstraZeneca shot, rates were practically identical after a period of four weeks.  

Many groups at a greater risk from Covid-19—including those with underlying conditions like diabetes and cancer, those taking immune system suppressing drugs and older adults—produced fewer antibodies after a single dose, a potential problem for countries like the U.K. where the second dose is delayed by several weeks in order to vaccinate more people.

However, a second shot boosted antibody levels to the standard high levels, something Professor Rob Aldridge, the chief investigator of the study, told the Guardian underscores the “importance of getting the second dose.”        

Aldridge described the findings as “reassuring – vaccines are our way out of the pandemic.”



Dr. Maddie Shrotri, the paper’s lead author, said the findings are from some of the earliest “real-world vaccine studies in the U.K.” Shrotri said the results are “fantastic news,” adding that it is “remarkable” how well the vaccines work 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.”


57 million. This is how many vaccines have been given out in the U.K., the vast majority being the Pfizer-BioNTech or AstraZeneca shots. Just over 20 million people have received their second dose.