Scientists have warned the government that allowing large numbers of people in lower-income countries to go unvaccinated is "reckless" and could lead to new Covid variants.
More than 320 experts have written to Prime Minister Boris Johnson, calling for urgent action. Some 13 scientists who sit on the UK government's scientific advisory committee, Sage, have also signed it.
They say more than three billion people globally have not had a first dose.
In their letter, the experts argue that the Omicron variant is a stark warning of the dangers posed by global vaccine inequality. Jabs can help keep infections low, giving the virus fewer opportunities to mutate.
They are asking ministers to support moves to waive the intellectual property rights on Covid vaccines so that developing countries can manufacture their own versions.
Former NHS chief executive Lord Crisp was one of the letter's authors and said vaccinating the world was the best way to keep the health service safe.
"The solution is global solidarity - working together and that means partnership," he said. "It means - in the short term - releasing some of these patents in order to deal with this pandemic..."