He said he'd introduce them, now Boris Johnson has stepped back from mandating vaccine passports across England for venues like nightclubs. But what's provoked this viral volte-face? Also, saliva tests for Covid-19, few fatal coronavirus cases among the unvaccinated, what's the role of hand sanitisers, and are Covid booster jabs the way forward? Dr Chris Smith joins RNZ's Kim Hill to discuss the latest Covid-19 news... Like this podcast? Please help us by supporting the Naked Scientists