KATE KELLAND THE Pfizer-BioNTech COVID-19 vaccine may be less able to protect against infection with a South African variant of the virus that has a worrying mutation, according to results of a British study released yesterday. The preliminary data, which have yet to be peer-reviewed and involve a small number of patients, also suggest a significant proportion of people aged over 80 may not be sufficiently protected against new variants of the virus until they have had two doses of the vaccine, researchers leading the study said. "Of particular concern ... is the emergence of the E484K mutation (found in…