London: There aren't many places left for the COVID-19 virus to mutate and evade immunity as it will only get weaker with time, said the creator of the Oxford-AstraZeneca vaccine, the most widely distributed jab in the world. “The virus cannot completely mutate because its spike protein has to interact with the ACE2 receptor on the surface of the human cell, in order to get inside it," Dame Sarah Gilbert, the lead scientist from Oxford University, and the brain behind the vaccine manufactured in India as Covishield, said during a webinar titled: ‘Vaccines, variants, and infection: The position this winter’ for the Royal Society of Medicine on Wednesday. “If it changes its spike protein so much that it can’t interact with that receptor,