The new Omicron variant is coming at us like an express train. If cases double every two and a bit days – three times in a week – that means eight times as much infection after one week, 64 after two, 512 times after three … It now seems Omicron is highly efficient at evading two doses of vaccine. What we don’t know yet is how likely it is to cause serious disease and death. Given that hospitalisations lag after infections and deaths after hospitalisations, it is simply too early to tell. However, even if Omicron were only a half or a quarter as serious as Delta in terms of hospitalisations, that would still lead to enough admissions to overwhelm a fragile NHS. This is an NHS already depleted by 10 years of austerity, with staff burnt out by two years of dealing with Covid and, since “freedom day” on 19 July, dealing with consistently high levels of Covid admissions. To do nothing right now and stand by as cases spike would be akin to playing Russian roulette. While you just might get lucky and cases might not translate into hospitalisations, and a creaking NHS might stay standing, there are plenty of chances that this will not be the case, and it really isn’t a good idea to play such a lethal game with public health. When it comes to what precisely we should do to slow down Omicron, it is important to avoid serious confusion. Omicron must be slowed down to buy time to vaccinate people. As well as making people safer, we should also be acting fast to make environments safer by, for instance, ensuring that all classrooms, workplaces and leisure spaces are properly ventilated. But vaccination is not the means of achieving the slowdown right now. That is because the rollout takes time, and after we get boosters it takes a couple of weeks for the benefits to kick in. So there are other things we must do to achieve an immediate effect. First, we must be clear in communicating that there is a direct relationship between the number of contacts we have and the spread of infection. This makes things very simple. You want less infection? You need to have fewer contacts. You can try to do it by persuasion. You can do it by legislation. That is a difficult debate. But there is no question that it needs to be done. Because if we want Christmas, we must meet up less before Christmas. When we are in contact with each other, we need to make that contact safer. That means distancing, mask-wearing, ventilating or (preferably) meeting up outdoors. It also means testing to make sure we don’t meet others if we are infected. Doing a lateral flow test before going into any public venue or meeting up in private is not a perfect solution. These tests are not a green light to say “abandon all caution”. But they are an important additional protection. If we do test positive, or if we have been in close contact with someone who has tested positive, we must isolate. That should be the most basic rule of all. It is the only way to take infected people out of circulation and break the chain of transmission. For these various things to be happen, we need a government that has the competence to communicate these messages clearly and consistently. We need it to have the moral courage to institute policies and to tell us unwelcome truths we might not like to hear. Putting on a Santa hat and telling everyone to party like there’s no tomorrow might be what the public wants the prime minister to do, but it is the mark of good leadership to tell the public instead, “I’m very sorry, but don’t party or else there will be no tomorrow.” We also need a government that has the moral authority to ask us to act responsibly because it takes its own responsibilities seriously. If our leaders ask us to get tested and to self-isolate, they need to ensure that we can afford to find out we are infected and to isolate ourselves. They have never done that. Support for self-isolation has always been hard to get. It has been too little. It has been too narrow. It is now more important than ever to set that right. But right now, clarity, competence, moral courage and moral authority are hardly the first things that come to mind when describing our present prime minister and his government. Our politicians have created a sense of “them and us”. Still worse, their actions have created a perception of contempt for the poor public who have been obeying the rules. When a government comes to be seen as a toxic other, trust and influence are squandered. The public mood becomes one that says, “They have no right to tell us what to do.” So it all seems pretty bleak. Just as we need an urgent national response to a new crisis, we lack the leadership to coordinate it. But there is a silver lining, and we see it more clearly if we look back to the effects of the Dominic Cummings fiasco. That, too, replaced any sense of unity between public and government with a division between “them” and “us”. That, too, led to a catastrophic loss of trust in Westminster politics specifically. That, too, undermined adherence to the rules – or at least gave those already inclined to break the rules an excuse to do so. At the same time, though, many people – especially those most angry at Cummings – adhered more in order to show that they weren’t like the government, to show that they followed the rules and cared for their community. This explains an otherwise puzzling fact. Despite the fact that after the Cummings revelations trust in the government in London plummeted while trust in the devolved administrations stayed largely constant, levels of adherence to Covid measures around the UK did not change. The reason for this is simple. The government is just one of many sources people listen to around Covid. They also listen to scientists and medics and to each other. Indeed, our own data shows that trust in scientists is more important than trust in government, and this is reflected in the fact that, by and large, people are “following the science” more than the government – becoming cautious and supporting the introduction of Covid measures as cases rise. Equally, a wealth of data shows that the norms of one’s peers and of the groups one identifies with are a critical determinant of attitudes and behaviours around Covid. Throughout this pandemic, there has been a question mark over the public’s ability to put up with the measures necessary to control Covid – as if the public are the weakest link and are holding back the ability of government to protect us. Time and again the evidence points to the opposite: that a resilient public are being let down by their government. Right now, we remain largely resilient. We continue to adhere despite clear anger at our prime minister’s behaviour. But this can only constitute partial consolation. In the midst of the greatest challenge of our generation, our government – by its own actions – has compromised its own ability to play a part in keeping the public safe. That is the true cost of Downing Street’s Christmas parties. And it is we, the people, who are paying that cost. Stephen Reicher is a member of the Sage subcommittee advising on behavioural science