Every epidemic follows a similar dramatic arc. First comes disbelief and denial. Next, progressive revelation that the threat is real and that it’s spreading. The final act is crisis, followed by recrimination and the search for scapegoats.

Judging by the events of the past seven days, we are now in full coronavirus crisis mode. On Wednesday, as some British schools sent pupils who had recently visited Italy home while others elected to stay open, headteachers accused Public Health England of issuing “confusing and contradictory” advice to parents.

Does the government have a coherent plan to mitigate the worst impacts of what increasingly looks like a pandemic?

And there is panic too. Almost £100bn was wiped off the value of the FTSE 100 in just two days of trading on Monday and Tuesday. And on Wednesday the oil giant Chevron instructed 300 staff to stay away from its Canary Wharf headquarters after an employee developed flu-like symptoms following his return from Italy, even though the official government advice is that there is no need to close workplaces. Meanwhile, in Milan, which lies outside the quarantine zone, supermarket shelves have been stripped of pasta and fresh vegetables by worried shoppers, and museums and other public buildings are shut.

So how concerned should we be about Sars-CoV-2, as the virus is formally known? Does the government have a coherent plan to mitigate the worst impacts of what increasingly looks like a pandemic? And what can the experience of previous pandemics tell us about how best to respond to this one? Fifteen years ago, while researching my book Living With Enza, I asked similar questions. Then, south-east Asia was in the midst of a major outbreak of bird flu and there was a panic about a possible pandemic of H5N1 avian influenza.

The last time a species of bird flu had triggered a major pandemic was in 1918-19 when the so-called Spanish flu had encircled the globe, killing 50 million people worldwide, the majority of the victims being adults between the ages of 20 and 40. In 1918 there were no antibiotics or antiviral drugs to mitigate the severity of the infection, and no vaccine to prevent the virus’s transmission, so deaths were off the scale. Nevertheless, in 2005, David Nabarro, the United Nations coordinator for avian and human influenza, warned that the H5N1 virus might result in the loss of anywhere “from 5 million to 150 million lives” globally.

In the event, the pandemic never happened and by 2009 just 282 people worldwide had died of H5N1. Instead, it was a novel strain of swine flu, emerging unexpectedly in Mexico in the spring of 2009, that sparked the next pandemic. Then as now, there was panic: in response to a statement from England’s then chief medical officer that as many as 65,000 Britons might die, the National Pandemic Flu service crashed. We also saw the same debates about the utility of face masks and the same public health messages about the importance of covering one’s mouth when coughing and sneezing. And while some schools closed, others remained open.

Just 457 Britons died in the swine flu pandemic,

a fraction of the number who die in a normal winter flu season, prompting many people to ask what all the fuss had been about. Some politicians, noting how the World Health Organization’s pandemic declaration had been a windfall for vaccine manufacturers, even described swine flu as a “fake pandemic”.

It is to avoid being accused of provoking a similar “scare” that the WHO is being so careful this time round. Hence, the refusal of Tedros Adhanom Ghebreyesus, the WHO’s director general, to use the p-word, even as the coronavirus threatens to overwhelm global supply chains and send stock markets plunging to new lows. Instead, we have had talk of “a potential pandemic” and of windows “narrowing”.

At a press briefing in London on Tuesday, infectious disease experts, many of whom advise the government, were similarly close-lipped. There was no point getting “hung up” on the term pandemic, said one. The important thing was for PHE and other national bodies to continue with measures to mitigate and contain the spread of the virus. Nor would anyone comment on how many Britons might be infected should the coronavirus begin spreading more widely, much less how many might die.

Despite quarantines and travel bans, the virus has spread to every continent except Antarctica in three months

In 1918, as now, British health officials adopted a laissez-faire attitude to the Spanish flu. Then, as now, the official advice was to cover your mouth when coughing and sneezing, and isolate yourself at home if sick. The question of whether or not to close schools was left to the discretion of local authorities. Keen to reinforce morale on the home front, British newspapers also underplayed the threat, with the Times telling its readers that fear was “the mother of infection” and that “to go about expecting influenza is to invite it”. Meanwhile, Arthur Newsholme, the head of the Local Government Board and the highest medical officer in the land, said the needs of war demanded that Britons “carry on”.

Expect a similar business-as-usual message this week when the government unveils its public awareness campaign. People will be urged to cover up sneezes and coughs, wash their hands for up to 20 seconds and self-isolate at home and dial 111 if sick. To reduce the burden on GPs, the NHS is trialling “drive-through” coronavirus testing at select London health centres. The key message will be “protect yourself and protect others”.

What you won’t hear is any reference to projected casualties or whether the NHS has sufficient critical care beds if mitigation fails and we have to step up the response to Chinese levels. The good news is that while the virus has spread to at least 50 countries worldwide, cases in China are declining, suggesting that the draconian quarantines in place in Wuhan and other Chinese cities since January are working. The bad news is that, unlike influenza, to which everyone has some immunity, no one has immunity to Covid-19. And we still don’t know whether it can be spread by people without symptoms or what percentage of those who require hospitalisation for severe respiratory illness will die.

What we do know is that despite quarantines and travel bans, the coronavirus has spread to every continent on the globe with the exception of Antarctica in just three months. In many ways, it’s the perfect predator: most people do not know they’re infected until it’s too late. And while the elderly appear to be more susceptible to severe illness and death than people in younger age ranges, some of the victims have been in their 30s. That is not necessarily a reason to be afraid, but it is reason to take the coronavirus seriously.

• Mark Honigsbaum is a medical historian and author of The Pandemic Century: One Hundred Years of Panic, Hysteria and Hubris