fundamental step in handling an outbreak of an infectious disease is to locate where it originated and prevent any more cases of the disease coming into your community or country. If you can cut off the source, you can devote your resources and efforts to suppressing its spread, and coping with the health and social problems it has created. The approach of imposing isolation on arrivals, known as quarantine, is centuries old. At a time when an understanding of the nature of infectious diseases was virtually nonexistent, it was one of the few control methods that worked. In times of plague and pestilence, cities and states often applied it with enormous rigour. Almost a year after the World Health Organization declared that Covid-19 was a “public health emergency of international concern”, the UK government is imposing a regulated quarantine regime on some international arrivals. This extraordinary delay illustrates perfectly how far the country has distanced itself from its previous position as one of the leading exponents of public health in the world. It also demonstrates a pattern in the government’s handling of much of the pandemic response – taking action far too late and, even then, doing it halfheartedly. It was not until 8 June that the government introduced a requirement for people arriving from most foreign countries to self-isolate for 14 days, later reduced to 10 days. The regulations were accompanied by the possibility of fines being issued for non-compliance. There is, however, little evidence of compliance with this system and a vanishingly small number of penalties appear to have been imposed. Covid-19’s ability to mutate and produce variants that may have decidedly different characteristics from their predecessors has forced the government’s hand. Priti Patel announced compulsory quarantine arrangements, involving hotel stays for passengers who cannot be refused entry, such as British residents and nationals returning to the UK, who are travelling from a limited number of countries, including known variant “hotspots”. These modest and disappointing proposals will undoubtedly run into several severe problems that could and should be avoided. Importantly, these new regulations do not replace the failed system of what amounts to voluntary self-isolation for the inadequate period of 10 days. The compulsory quarantine only applies to people travelling from the 22 high-risk countries. Everyone else arriving in the UK will continue to have to self-isolate according to the existing regulations. There can be no such thing as a partial quarantine. Either it is comprehensive and effective, or it will fail. A differential approach based on country of origin is undermined by the difficulty of accurately ascertaining where arrivals have come from. Global travellers may move across many countries during their journey and use various means of transport. During their travels, they may well have passed through multiple travel hubs and departure lounges, encountering and spending time close to many other travellers along the way. Determining who will be subject to self-isolation and who will be subject to mandatory quarantine will probably be a valueless task. Experience from elsewhere shows that operating an effective managed isolation facility is no easy undertaking. Preventing people who are isolating from mixing with others in the same position, in the same facility, such as a hotel, is difficult. In Australia, serious problems arose because of very close contact between people isolating and those working at the facilities. Whatever system of quarantine is adopted, the government needs to break with its insular habits and learn quick lessons from the successes and failures of other countries. An important rule for a quarantine system is that few, if any, exceptions should be permitted. Limited observance and the extensive list of groups that do not have to observe the rules will limit their effectiveness. There are up to 60 occupations or groups potentially exempt from isolation requirements, including everyone from bus drivers to workers in data system maintenance. One exempt group we should be concerned about are those commuting internationally at least weekly. Anyone can bring the virus with them, and everyone should have to go into managed isolation – especially if they travel often and have a greater chance of catching a new strain of the virus. After reaching a disgraceful toll of 100,000 deaths, it is time to focus on some key public health objectives. The government’s mantra on Covid-19 should be: “Get it down, keep it down, and keep it out”. That is how to maximise the benefit of the mass vaccination campaign and avoid it being undermined by variants. As recently as July and August, the UK and Australia had very similar daily new Covid-19 cases per capita, with Australia at times higher than the UK. Since then, Australia has succeeded in eliminating the virus. Successful quarantine and rapid response to flare-ups have created that success. The UK has no strategy, no overall objectives and no chance of making a half-baked quarantine scheme work. Gabriel Scally is visiting professor of public health at the University of Bristol and a member of the Independent Sage committee