Covid vaccine, UK Health Minister Matt Hancock announces large-scale trial on third dose. During a briefing in Downing street, the minister explained that the campaign will be carried out with all seven vaccines ordered by the UK and calibrated to discover the protective effect on the new variants. According to reports from the BBC, the vaccines will be tested on people of working age and over 75 to collect data on side effects and immune responses. The government urges the population to take part in the trial that will allow, among other things, to understand if it will be necessary to distribute the third dose of the vaccine already in the fall. Hancock hopes for thousands of volunteers for the third dose trial.