Pharmaceutical

US President Donald Trump has signed a revised version of his controversial travel ban. The policy, issued on 6 March, exempts citizens of Iraq and people who were issued US visas before 27 January — including those with green cards. Like the first order, which Trump signed on 27 January, the revised policy bars citizens of Iran, Libya, Somalia, Sudan, Syria and Yemen from entering the US for 90 days. Many scientists affected by the first policy have struggled to understand whether it is safe for them to leave the United States to visit family, attend scientific conferences or conduct research. The revised policy might not offer these people much comfort. There are man...