HOW did that happen? Britain has vaccinated an astonishing four million vulnerable people against Covid-19 only three weeks into the New Year. Government ministers and the NHS are beside themselves. Critics are dumbfounded. After all the problems of mass testing, it seems there's something we can actually get right.

It is indeed a genuine cause for celebration, assuming momentum is maintained. Seeing the gratitude of elderly people, who haven't been out of their homes since April, as they get their jabs would melt a heart of stone. So it seems churlish and mean-spirited to question this rapid roll-out, but question we must.

For there is a nagging undertow to the celebration and high-fiving. In the rush to immunise our own people, are we condemning millions in poor countries? Are we behaving like those wealthy first-class passengers on the Titanic who secured their seats in the lifeboats while the steerage passengers were kept behind locked doors? The World Health Organisation thinks so. This “me first” approach is a “catastrophic moral failure”, according to its chair, Dr Tedros Adhanom Ghebreyesus.

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Wealthy countries are well on the way to cornering the market in life-saving Covid vaccines. Millions upon millions have already been seized – enough to vaccinate everyone in the wealthy countries three times over, according to the People's Vaccine Alliance, a network of NGOs and charities including Oxfam. Canada has already grabbed enough doses to immunise its entire population five times.

Meanwhile the 70 lowest-income countries will only be able to vaccinate one in 10 of their citizens this year if they're lucky. There just isn't enough to go round – or rather there is, but it's not getting around fast enough. The World Health Organisation is appealing to the rich nations to rein back their bilateral drug deals long enough to ensure that all countries start vaccinating in earnest within 100 days.

Some hope. This is one of those occasions where the realities of wealth and power become starkly obvious. And this is not just about corporate capitalism making billions out of human misery. That has been a convenient red herring. AstraZeneca is making no profits out of the Oxford vaccine. This is about you and me, and personal morality.

And it is an intensely difficult question. To put it bluntly: would you be happy to see your granny risk death so that a health worker in Zimbabwe could be protected? Posing the question like that may seem offensive, even indecent, but let's be honest. Would you really want Nicola Sturgeon to halt the rapid roll-out of Covid-19 so that developing countries could catch up? Probably not. As Bruce Springsteen put it: “we take care of our own, wherever this flag's flown”.

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Health inequality is a most difficult moral question to address precisely because we're all essentially hypocrites. We believe that everyone should be treated equally, but we don't really mean it. If your father was, like so many in Britain right now, in agony because of a delayed hip operation, and you had the cash, you'd pay for it to be done privately, wouldn't you? There is no clear ethical justification for putting family or country first, but invariably we do. It's only human.

It isn't just Covid-19 either. People in African countries died needlessly from HIV/AIDS long after life-saving drugs had been developed to save lives in the West. There are areas of the planet where diseases like tuberculosis are re-emerging after they have been largely eradicated here. Cancer is no longer a certain death sentence in developed countries but it remains a killer in what we used to call the Third World. Indeed, it would be an even greater killer were it not for the fact that poor people often don't live long enough to contract it.

However, there is little point in beating ourselves up about this. Nations will always put their citizens first, because that's what they are there for. And global inequality is not going to be reversed in a pandemic. We should accept our good fortune with good grace and move on. Then make sure the rest of the world catches up as fast as possible. Indeed, it probably doesn't make much epidemiological sense to halt the roll-out of the vaccine in Britain right now.

In the medium term, the developed world has a direct interest in seeing Covid defeated in countries like Zimbabwe. Global herd immunity will not be reached until the disease is conquered in developing countries as well as in the West. Travel restrictions will not be lifted. As the recent Covid variants from South Africa and Latin America have demonstrated, we need global immunity to prevent this deadly bug coming back to bite us with its own viral version of herd immunity.

HeraldScotland: WHO Director-General Tedros Adhanom GhebreyesusWHO Director-General Tedros Adhanom Ghebreyesus

Some suggest that developing countries are too corrupt to be trusted with mass vaccination programmes. Not so. The elites in poor countries will no doubt do their own local queue-jumping, as they do with aid money. But there is no evidence that any countries – even in the war-torn Middle East – lack the capacity to deliver a simple jab.

Manufacturing the vaccine isn't the main problem either. It is being produced in massive quantities. It's really just a question of who gets first dibs, and I'm afraid it is us. We should at least be honest about it. People on social media rant about white privilege, male privilege and even binary privilege. But the truth is that we are all of us privileged because we live in wealthy countries with sophisticated health systems. This is the real “vaccine gap”.

What would clearly be morally inexcusable is if we end up this summer vaccinating people under 40, who are most unlikely to die, while vulnerable groups elsewhere are still waiting. The World Health Organisation has been rather astute in calling for the 100 poorer countries to get the vaccine by World Health Day in April. That seems eminently doable and reasonable. After all, had it not been for rich countries and their wealthy pharmaceutical companies, there wouldn't have been a vaccine at all.

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