coronavirus vaccine may reduce transmission by 67%, a study claims. Scientists say the jab also offers protection of 76% up to 12 weeks after a single dose.And it rose to 82% after people were given the second dose, according to researchers from the University of Oxford.The findings were hailed as showing how vaccines are the way out of the pandemic.The study, on 17,000 people in the UK, South Africa and Brazil, supports the four to 12-week gap between doses many global regulators have recommended.Before the results, little was known about how effective the Covid-19 vaccines were at preventing transmission of the disease.This is key as by stopping the virus spreading, it means people who have been vaccinated are indirectly protecting others.