MORE THAN 150 covid-19 vaccines are being developed worldwide. Six are in final, large-scale clinical trials. Governments have invested $10bn in them and are reckoned to have made forward purchases of about 4bn doses. Effectiveness is not assured: 20% of vaccines fail in final trials and some covid-19 vaccines rely on new technologies, raising the risk of duds. An extravagance? Far from it. The real waste, in output and lives, would be to wait for a successful vaccine before boosting production. Even $100bn would pale next to the $7trn governments have spent or pledged on supporting incomes and jobs. The huge investment required raises fears of “vaccine nationalism”, with rich countries outspending the poor and hoarding supplies. It is easy to imagine countries squabbling, with poor countries likely to lose out, despite international efforts to promote fairer distribution. Maximising supplies quickly and spreading manufacturing capacity around the world would help minimise the scramble.