As China abruptly dropped some of its toughest Covid-19 restrictions – including scrapping quarantine rules for travellers, experts are watching nervously to see how this may impact Covid-19 variants and their global spread, with some countries already ramping up precautionary measures. The decision on Monday to drop quarantine for overseas visitors from 8 January has prompted concerns about the potential for new variants beyond China’s borders.  Japan and India are among the countries that have introduced measures to prevent an influx of cases China’s move to open up travel sparks concern over spread of new Covid variants