Vaccinated people are 30 per cent less likely to pass on Covid after their first dose and less than half as likely to after two doses, a study has suggested. A study of 300,000 NHS staff in Scotland found it became significantly less likely that someone living with a health worker would test positive if the medic had been immunised. Scientists are already sure that jabs will prevent severe illness and death but how well they stop the virus spreading is uncertain. Carried out by Public Health Scotland and the University of Glasgow, the study raises hopes that vaccines could soon spell the end of nationwide outbreaks of the virus.