Three vaccines have been approved by stringent regulators. Ten are being used in one or more countries. How do they work and are they effective enough against new variants of the coronavirus? Sarah Gilbert, inventor of the Oxford/Astrazeneca vaccine, tells us adapting to new variants should be easy. The Economist’s Beijing bureau chief David Rennie reports from China, which faces a huge test of its homegrown vaccine technology as it tries to re-open. James Fransham from our data team on how far the variants have spread. Alok Jha, The Economist's science correspondent, hosts with our health policy editor, Natasha Loder. Slavea Chankova, The Economist's health-care correspondent, joins them. For full access to The Economist’s print, digital and audio editions subscribe at economist.com/thejabpod and sign up for our new weekly science newsletter at economist.com/simplyscience   See acast.com/privacy for privacy and opt-out information.