"There is a tidal wave of Omicron coming". That was the chilling warning of UK prime minister Boris Johnson on Sunday night as he announced a new 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. So far, the NHS in England 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 the next three weeks.

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

Johnson's statement was marred by suspicions that he is using the booster campaign to distract from an ongoing scandal about the behaviour of his own staff. And later today, Johnson will face the wrath of his own 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. to curb the spread of Omicron. Around 75 are expected to vote against the measure, which will leave Johnson dependent on votes from opposition parties to get his plans through Parliament.

But some think this is all a distraction from the real issue. They claim the developed world is greedily hoarding booster shots when much of the rest of the world is still unvaccinated.

In part, this is a question of distributive justice. They think it is unfair that some people should get three jabs in a year, while others are still unprotected from the virus. 

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" before it was created, without knowing what place in society they would ultimately hold. We might not be so quick to support the booster rollout in rich countries if there were a chance that 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, like Omicron, will be more transmissible than previous strains, and resistant to vaccines.

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

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

And they point out that the problem for the developing world is not vaccine availability: many poorer countries simply do not have the resources to administer vaccines quickly to their whole populations. 

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

Yes, say some. Some 3.5 billion people around the world still have not received even one dose of Covid-19 vaccine. That means millions of unnecessary deaths in countries whose healthcare systems are ill-equipped to deal with them. And everyone ultimately suffers when new variants appear.

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

Vaccine passports - Many countries have introduced passes based on vaccination status or recent tests to enter some public spaces and business.

John Rawls - An American political philosopher who was extremely influential in the development of 20th-Century liberalism.