Despite what Matt Hancock says, the government's policy is still herd immunity

When the lockdown is lifted, will the virus return? Of course it will. Matt Hancock has said we will do 100,000 tests each day by the end of April, but Britain still doesn’t have a way to control the virus that goes beyond lockdown. Without a proper programme of community surveillance and contact tracing, we won’t stop the spread of coronavirus. As patients pour into hospitals again, a series of national lockdowns will follow. It’s a pattern that could go on for years – until we have a vaccine.

The problem with Hancock’s plan is that testing alone won’t break the chain of community transmission. To stop the spread of a virus, tests must be linked to community surveillance and contact tracing. This ensures that people who have the virus, and people they have come into contact with, can be identified quickly and quarantined at home to prevent the virus spreading. The government’s tests will measure how many people have had the virus, and will show whether health workers are immune – but without community surveillance, tests alone won’t prevent its spread.

On 12 March, the chief scientific adviser, Patrick Vallance, and chief medical officer, Chris Whitty, announced that the UK had moved from containing the virus to delaying its spread. Their plan was to flatten the curve of the epidemic that would sweep through our population. They reassured us that herd immunity would kick in once 60% of the population had been infected. Social distancing and washing our hands would ease the pressure on health services, they said. Crucially, community testing and contract tracing would stop immediately. At that point, we were still four weeks behind Italy. The media felt safe, reassured by two eminent physicians.

The trouble is, those scientists were wrong. The maths wasn’t difficult: working off their figures, about 40 million people in the UK would be infected by coronavirus, and between 200,000 and 400,000 would eventually die. When the government’s mathematicians modelled figures from Italy and showed that 30% of people admitted to hospital ended up in intensive care, they warned the government that the NHS would be overwhelmed. The government backtracked within three days, and shifted to suppressing rather than mitigating the virus.

In reality, little changed. The government’s beliefs were founded on the assumption that coronavirus behaves like flu. It doesn’t. Its mortality rate is higher, there is little evidence that it is seasonal, and it poses a far greater threat to the NHS. Without a programme of community surveillance and contact tracing, the virus will continue to spread. Britain will be subject to routine flare-ups and repeated lockdowns.

I spoke to a senior international epidemic expert, who wished to remain anonymous. They described the UK’s response as too weak. “Finding these viruses is like guerrilla warfare. If you don’t know where the virus is hiding you cannot control it. We must use a bundle of measures to chase it. We must organise teams of friendly community workers to find people with symptoms, test for the virus, isolate and treat them, and trace their contacts. Workers must check on them in their homes every one or two days,” they said.

I asked them whether social distancing alone could beat the virus. “It won’t work,” they told me. “You can stop contact tracing in the hotspots, but when you lift the lockdown, everywhere at the same time, you’ll face a problem: the virus will come back. New hotspots will form.

“Without a community programme for case detection and contact tracing, you won’t find the virus until it’s too late.”

In China, Xi Jinping initially prevaricated, suppressing the findings of a fact-finding mission on 4 January that investigated the outbreak in Wuhan. But by 26 January, China had placed more than 50 million people under quarantine; 40 provinces reported a total of 2,744 cases and 80 deaths. The Chinese communist party mobilised thousands of community workers to scale up a national testing effort, while mapping infections using case definitions based on symptoms.

Almost 40,000 health workers were flown in from across China to help with this huge community surveillance effort. The government enforced regional lockdowns, closed down shops, bars, universities and schools, and policed the supermarkets and pharmacies. They developed apps to monitor peoples’ symptoms and their compliance with quarantine, and set up 24-hour TV channels in every province to update people on data, progress and prevention. With this comprehensive response, China managed to suppress the transmission of the virus in less than two months.

By contrast, the UK was slow to act, and timid when it did. The government mistakenly based its coronavirus response on social distancing alone. The UK’s Scientific Advisory Group of Experts (Sage) didn’t even ask their mathematical advisers to model a community testing programme. Neil Ferguson reportedly said community testing and contact tracing wasn’t included as a possible strategy in the original modelling because not enough tests were available. But we had eight weeks’ notice.

We still don’t have a coordinated mobilisation of general practices and public health outbreak management teams. None are linked with digital apps or laboratory testing. In one of the best research cultures in the world, we failed to create the community surveillance and testing effort needed to stop the spread of the virus.

The government and its advisers are now committed to their strategy of delaying the spread of coronavirus, which they hope will eventually lead to herd immunity. Our present predicament is a symptom of past decisions: the decision not to roll out testing sooner put the government on the back foot, scrambling to catch up with the virus.

But it isn’t too late. To prevent the spread of coronavirus, we need a change of direction. Local authorities must take control of their public-health outbreak management teams. We need a centralised app and database to allow citizens to report their symptoms, such as the NHSX app that researchers have been working on since January.

GP networks, working with teams of trained volunteers and retired health workers equipped with personal protective equipment, could visit everyone reporting suspicious symptoms at home every one to two days. If there is testing, all the better. But symptom-based reporting will do. With a proper community protection scheme in place, local authorities could shield their population from the threat of the virus, which has taken hold in hotspots like London and the cities of the Midlands and north west.

The lockdown will flatten the curve, but we have a month or more before it lifts. This gives us time. To prevent the virus spreading to less affected areas, we have a choice: a dramatic change of direction, or praying that vaccinologists can work miracles.

• Anthony Costello is professor of global health at UCL, and former director of maternal and child health at the World Health Organization