By the end of March, one week into the UK’s first lockdown, recorded crime in Lancashire had dropped by a startling 40% compared with the four-year average.

“At first there was some mild panic,” says DCI Eric Halford, of Lancashire Constabulary. “Most senior officers expected a surge in demand.”

To be fair, policing a lockdown didn’t feature in the force’s institutional memory. Nevertheless, nearly a year into the pandemic, it is clear that crime did not dry up, it just changed, in search of new opportunities presented by a health crisis that has affected every aspect of our lives – and in ways that were not always immediately visible to those who enforce the law.

During the spring, when many countries imposed lockdowns, traditional crimes such as shoplifting and burglary fell because shops were closed and people were stuck at home. However, cybercrime, domestic violence and antisocial behaviour rose – the latter probably due to breaches of Covid-19 restrictions. When lockdowns were lifted around June, these trends reverted to some extent.

Those who did commit traditional-type crimes adapted their ways of working. Armed robbers in California realised that face masks offered convenient anonymity, as did two fastidious men who held up a post office in Luton, England, sporting latex gloves.

Thieves coveted new categories of objects. Oxygen canisters were stolen from hospitals; food banks were raided. And though violent crime fell in general, during lockdown a new category of assault came into being: malicious coronavirus coughing. When the culprits are children, they risk exclusion from school. Adults, whose victims have included key workers, risk prison.

Also bucking the general decline in violence was a rise in domestic abuse during and immediately after lockdown. This crime is dramatically under-reported as a rule, but charities reported a big increase in calls for help and evidence that the violence was escalating quickly – something police had anticipated.

“We started placing officers and independent domestic abuse advisers at supermarkets and other places we thought victims would be allowed to visit, in the hope we could offer a way out,” says Halford.

Children were more often the victims of violence too, including online and offline sexual abuse. School closures and a lack of alternative safe venues exacerbated the problem in some countries, says Heather Flowe, a forensic psychologist at the University of Birmingham, because children were either left alone at home when their parents went out to work – sometimes with access to the internet – or roaming the streets.

In Kenya, where President Uhuru Kenyatta ordered an investigation into the problem in July, Flowe’s team has surveyed more than 1,000 abuse survivors, with troubling results. “The average age of children in our sample is four years younger than it was pre-pandemic,” she says. The drop – from 16 to 12 – can once again be explained by changing patterns of opportunity, Flowe says.

After the 2014 Ebola epidemic in Sierra Leone, when safeguarding measures were put in place for young children, more older children were victimised – and there was an increase in teenage pregnancies. This time the offenders have often been neighbours, or individuals who are themselves spending more time online.

“Given the ‘right’ circumstances, the potential for ‘normal’ individuals to perpetrate child sexual abuse is more widespread than is perhaps comfortable to acknowledge,” wrote Richard Wortley, a crime scientist at University College London’s Jill Dando Institute, anticipating the problem in May.

Disruptions to global supply lines have affected illegal as well as legal markets. Data is rare on the impact of Covid-19 on human trafficking, but experts feared it wouldn’t be good, and there are indications that they were right.

Ilias Chatzis, of the United Nations Office on Drugs and Crime (UNODC) in Vienna, points to reports of women trafficked for prostitution being abandoned without papers or means of support at their destinations.

And though migration dropped dramatically when borders were closed, the push factors driving it are as strong as ever. “For people fleeing war, persecution or extreme poverty, a possible infection by Covid-19 in a safe country might be seen as a risk worth taking,” says Chatzis.

Drug smugglers have had to navigate less porous borders, too. To begin with, says Niamh Eastwood, the executive director of the UK centre for drug expertise Release, the UK’s illegal drug market proved remarkably resilient. Many dependent users turned away from heroin toward synthetic benzodiazepines, not because the heroin dried up but because their income from begging and shoplifting did – and “street benzos” are cheaper. “People can buy them for less than a pint [per pill],” says Eastwood.

Suppliers of party or club drugs, on the other hand, saw their market collapse during lockdown, only to revive later in the year. Now, though, droughts are pinching across the board, says Fiona Measham, a criminologist at the University of Liverpool.

Travel restrictions are making it harder for producers to obtain precursor chemicals and for dealers to obtain the finished drugs. “What happens when there’s increased droughts is the price goes up and the purity goes down,” Measham says, and there is anecdotal evidence that dealers are selling off substandard stocks that in normal times consumers would reject.

Fluctuations in purity are dangerous in any direction: up because the risk of overdose increases; down because people may compensate and then overdose when previous levels are restored. Additives can be dangerous, too. The powerful synthetic opioid fentanyl, which creates dependence rapidly, has been showing up in street drugs.

The stress of the situation seems to have taken its toll. “We certainly got anecdotal reports … that there was increased violence, but that was largely drug user on drug user,” Eastwood says. It could have been avoided, she thinks, if authorities in Britain had thought to ensure safe drug supplies as they have in Canada.

As their traditional markets in drugs and people dwindled, organised crime groups diversified, trading in personal protective equipment (PPE), pharmaceutical products and even funeral services.

Spotting a propaganda opportunity, in some places they extended their sway by stepping in to help where official responses to the crisis were seen to have fallen short.

In Japan, UNODC reports, Yakuza groups handed out free masks and toilet paper, while in Afghanistan the Taliban dispatched health teams to remote areas. Gangs in Cape Town, South Africa, called a temporary truce to hand out food parcels.

As new illegal markets emerged, the dark web embraced them. There was a roaring trade in PPE to begin with, and as early as March before a real Covid-19 vaccine was more than a glint in any pharmaceutical company’s eye you could purchase something masquerading as one for as little as $200 (though prices went up into the tens of thousands of dollars).

Were they sugared water? Experimental vaccines stolen from bona fide labs? Or concoctions made from people who had recovered from Covid-19? Nobody knows.

Occasionally, darknet vendors found some scruples. “You do not, under any circumstances, use Covid-19 as a marketing tool,” one darknet marketplace warned its users. “We have class here.”

But the surge in cybercrime spurred by the pandemic goes far wider than profiteering, says Benoît Dupont, a criminologist at the University of Montreal, Canada. Although some of it is organised, albeit by different groups than are active in traditional organised crime, plenty of sole traders and bedroom entrepreneurs have got in on the act.

The youngest perpetrators – some as young as 12 – may have been motivated by boredom or frustration, but it was also a case, again, of a gigantic opportunity. Witness the fraud that has parasitised government schemes offering financial support, with their light-touch checks.

The speed with which cybercriminals have reacted to the news cycle has been breathtaking, says Dupont. A front of phishing attacks, sometimes purporting to hail from well-known public health organisations, started in Japan in early February, swept into Europe in March, then invaded North America.

Cyber-attacks against hospitals and research labs followed a similar trajectory. Cybercrime surges are a recognised side-effect of disasters, but even the experts were blindsided by the scale of this one. “No one really thought that a biological virus would so quickly spur all kinds of digital viruses and that those two types of virus would be so tightly coupled,” says Dupont.

So what next for crime, given the pandemic is far from over? Though it’s too early to say how people have behaved in the latest lockdowns, with their generally lighter restrictions than in the first round, Clifford Stott, a social psychologist at Keele University, says the vast majority have probably complied with the rules – as they generally do, in mass emergencies.

“Where that’s not happening, it’s not because of a moral breakdown,” says Stott, who advises the government as a member of the Scientific Pandemic Influenza Group on Behaviours (SPI-B). “All the evidence suggests that people don’t comply because they can’t.”

Alternatively something happens – such as Dominic Cummings’ notorious northern run – to counter the narrative that underpins compliance, of “we’re all in this together”. For example, Stott says, generational tensions may now be emerging as young people chafe under restrictions designed to rein in a disease that mainly affects older people.

Pointing to the low-level confrontation or “quiet riot” that happened in Leeds last month, he says: “That kind of thing is going on all over the country.” Will local lockdowns produce local crime patterns and local responses such as neighbourhood or “cocoon” watch schemes? Police are waiting to see.

At the international level, Chatzis worries about the impact of the economic downturn. “A situation where economies are shrinking, where unemployment rates are high, where there is a great demand for cheap labour, creates perfect conditions for an increase of trafficking,” he says.

Dupont says cybercriminals are likely to consolidate their gains: “They are going from niche or boutique to mainstream.”

At the tail end of 2020, one criminal opportunity glitters more brightly than all the others: the Covid-19 vaccine, or vaccines, which Jürgen Stock, the secretary general of the global police coordination agency Interpol, recently compared to “liquid gold”.

The first of these have now been approved but have yet to be rolled out widely, while dozens of others remain in the experimental phase, creating an irresistible combination of high demand and short supply.

A black market in any Covid-19 vaccine, real or counterfeit, carries twin dangers: people who receive it may behave as if they are immune to the disease when they are not, endangering their own and others’ lives; and it could throw a spanner in the works of ongoing vaccine trials, whose integrity relies on scientists controlling who gets the real shot and who gets a placebo.

In September, the crime scientists Graham Farrell of the University of Leeds and Shane Johnson of UCL warned of possible thefts of vaccine shipments, bribes and backhanders for preferential treatment from suppliers, and even the chilling prospect of deliberate virus-spreading “to prime the market”. They urged governments to resist the temptation to wave through light-touch controls on vaccine supply lines, fearing that these would only fuel crime.

Since then, several fake Covid-19 vaccines have been seized, police have taken down online ads for others, and there have been reports of vaccine thefts and cyber-attacks on organisations that will distribute the real vaccines.

On 2 December Interpol issued an orange notice warning that vaccine crime represented “a serious and imminent threat to public safety” and calling on law enforcement agencies globally to stay alert. Since fraudsters were already hawking supposed Covid-19 vaccines back in March, nobody thinks the threat is hollow.

As Farrell and Johnson put it, “we may be walking into a crime storm”.