Total antibody levels appear to start declining at 2-3 after complete vaccination and can reduce by more than 50% over 10 weeks, according to new data from Virus Watch.
The clinical implications of waning antibody levels are not yet clear, but some decline was expected and current research shows that vaccines remain effective against severe disease.
The findings, published as a research letter* in The Lancet, include data from over 600 people taking part in Virus Watch.
You can read details of this analysis here:
https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(21)01642-1/fulltext
This work was reported on by multiple print and online media see links below.
https://www.ucl.ac.uk/news/2021/jul/vaccine-antibody-levels-start-wane-around-2-3-months