No adverse effects were created by the error, data show, but Cambridge scientists found such vaccines were not perfect and sometimes led to nonsense proteins being made instead of the desired Covid “spike”, which mimics infection and leads to antibody production. mRNA jabs, such as the ones created by Moderna and Pfizer, use a string of genetic material to tell the body to create a specific protein that safely imitates an infection. ... It was thought the minor tweak to uridine caused no problems in cells, but a team of researchers at the University of Cambridge’s Medical Research Council (MRC)...