"There is a tidal wave of Omicron coming". That was the warning of UK prime minister Boris Johnson as he announced a booster jab rollout.

The government aims to offer a booster vaccine to every adult in England by the end of December. This will be a Herculean task. The NHS has issued 19.4 million booster jabs. More than 39 million people have had two doses. So the NHS has to get boosters in around 20 million arms in three weeks.

The announcement comes after a study found two doses are not enough to stop from catching Omicron. People who got their second jab six months ago or more might have less than 10% protection. But a third dose has 75% effectiveness against symptomatic illness.

Johnson's statement was marred by suspicions he is using the campaign to distract from a scandal about the behaviour of his staff. Later today, Johnson will face the wrath of his MPs as he seeks to introduce vaccine passportsMany countries have introduced passes based on vaccination status or recent tests to enter some public spaces and business.. Around 75 are expected to vote against the measure, which will leave Johnson dependent on votes from opposition parties.

Some think this is a distraction from the real issue. The developed world is hoarding booster shots.

This is a question of distributive justice. They think it is unfair that some should get three jabs in a year, while others are unprotected. 

Some draw on the ideas of philosopher John RawlsAn American political philosopher who was extremely influential in the development of 20th-Century liberalism., who argued that a just world is one where everyone would agree to from an "original position", without knowing what place in society they would hold. We might not be so quick to support the booster rollout in rich countries if there were a chance we would be born in a developing country.

There is also a practical reason to prioritise jabs for the developing world. The more widely Covid-19 is allowed to circulate, the more variants it will produce. Many of these will be more transmissibleThe rate at which a virus passes from one person to another., and resistant to vaccines.

Then the whole planet is stuck in a cycle: a variant appears in the developing world, rich nations shut their borders and use up more vaccines to protect their citizens.

Others suggest the jabs that have been used for booster programmes are a drop in the ocean compared with demand across the developing world.

They point out the problem for the developing world is not vaccine availability: many poorer countries do not have the resources to administer vaccines quickly. 

There is no quick fix. In the meantime, there is no reason to let jabs go to waste when some countries can use them to save lives.

Yes. Some 3.5 billion people still have not received one dose of Covid-19 vaccine. That means millions of unnecessary deaths. And everyone ultimately suffers when new variants appear.

No. We live in an unequal world, we have to be pragmatic. Improving healthcare infrastructure is a long-term project. We should be manufacturing as many vaccines as we can manage, but refusing to use them in developed countries solves nothing.