A vaccine for coronavirus could be ready for use early next year, scientists have said. Pharmaceutical company Johnson and Johnson have announced they will start trials for the vaccine on humans later this year.If all goes well it is hoped the drug will be ready for emergency use in early 2021.The company aim to provide a global supply of more than one billion doses of the vaccine.Scientists across the world are working to create a vaccine for Covid-19 with some human trials already underway.Johnson and Johnson’s trial started development in January with a view to beginning human testing in September.The first batches of the Covid-19 vaccine could be made available through a substantially accelerated timeframe in comparison to typical