Back in November 1918, the San Francisco authorities thought they had beaten the deadly Spanish flu pandemic that had spread across the globe in only a matter of months. Infection levels in the city had peaked, then dwindled to apparent insignificance.
At the centre of the city a whistle blew, signalling the official end of four weeks of lockdown. Thousands of people tore off their gauze face masks and trampled them as they poured into the streets. Bars and theatres threw open their doors. The revellers ignored official calls to retain those masks.
Then a further wave of flu infections broke out that was far deadlier than what had come before. Ultimately, it left San Francisco with one of the highest death rates in the U.S. by the spring of 1919.
History shows how lethal disease pandemics have a habit of seeming to shrink away — but then returning suddenly in subsequent waves. Chillingly, these latter waves can prove far deadlier.
History shows how lethal disease pandemics have a habit of seeming to shrink away — but then returning suddenly in subsequent waves. Chillingly, these latter waves can prove far deadlier (file photo)
As British authorities try to plot a map for exiting lockdown from Covid-19, infectious disease experts are trying to fathom the deadly coronavirus’s next move. Almost all agree on one stark reality: that the infection is bound to re-emerge in a second wave.
Last week, for example, Professor Jonathan Van Tam, deputy chief medical officer for England, warned at the Government’s daily briefing that the virus will ‘absolutely come back’.
But what will that second wave be like? When will it strike? And is there anything we can do to blunt its lethal edge? As one expert — Simon Clarke, an associate professor in cellular microbiology at the University of Reading — told Good Health: ‘All these vital questions are at best the subject of educated guesswork.’
History does, however, provide us with fearsome lessons, in the form of the pandemics of the Spanish flu and before that, Russian flu, which swept the world at the end of the 19th century and the beginning of the 20th.
Last week, for example, Professor Jonathan Van Tam, deputy chief medical officer for England, warned at the Government’s daily briefing that the virus will ‘absolutely come back’
Most notorious is the Spanish flu in 1918 that infected a third of humanity — 500 million people worldwide — and killed some 50 million.
Yet the first wave in spring 1918 seemed like only a more contagious and virulent form of seasonal flu. It spread rapidly through England, France, Spain and Italy.
Mercifully, symptoms such as high fever and sickness tended to last only three days. The mortality rate was similar to seasonal flu, at less than 1 per cent.
Cases fell off during the summer. By August, it seemed the infection had run its course. Instead, the flu mutated into a vicious strain that could kill healthy young men and women within 24 hours of symptoms starting.
As the war drew to a close, thousands of British Empire and U.S. troops returned home, carrying the lethal contagion with them. The Spanish flu pandemic’s second wave began.
The global death toll from the second wave is still disputed, though experts generally agree that it claimed around ten times more victims than the first.
The infection was characterised by pneumonia that filled their lungs with suffocating fluid.
Decades later, doctors realised that these symptoms can be caused by a cytokine storm — a vast overreaction in the patient’s immune system that wreaks disastrous inflammatory damage to their lungs. Such storms are now considered to be a common cause of death with Covid-19 infection.
The same symptoms had also killed more than 130,000 Britons a quarter of a century previously, in the Russian flu pandemic. The infections also came in waves.
The first wave arrived in Britain in December 1889, killing around 27,000 people — and confining the prime minister, Lord Salisbury, to his sickbed for a fortnight. This wave began to dwindle in February 1890.
The second wave, a year later, proved far deadlier, killing 80,000. Worryingly, there was a third outbreak in 1892, which killed 25,000.
The idea that herd immunity might protect us against a second wave of Covid-19 is dismissed by Mark Honigsbaum, a medical historian at City, University of London, and the author of The Pandemic Century, who says evidence from these flu pandemics indicates that it’s not achievable.
It’s currently thought that to achieve herd immunity, where enough people in a community have resistance to a virus or bacterium that it stops spreading. Some 60 to 80 per cent of the population have to have been exposed to the virus and thus developed a natural immunity. But that may simply not be possible with Covid-19, says Mr Honigsbaum. ‘Historically in flu pandemics a substantial population of people will already have had some immunity, because they had previously been exposed to influenza viruses that share enough similarities with the pandemic virus for their immune systems to recognise it as an enemy,’ he says.
‘However, no one has any previous immunity from this new coronavirus because it’s not been around before. What’s more, we don’t know whether people who have recently recovered from it are immune now.’
And as seen in previous flu pandemics, even when large numbers of people are infected, that is still not enough to stop the virus returning in a second wave.
He adds: ‘While up to 80 per cent of the population will need to have been exposed to the coronavirus for herd immunity to develop, no more than a third of the UK population has ever fallen ill in a pandemic.’ This means that herd immunity seems statist- ically impossible.
Dr Shovonlal Roy, an associate professor of ecosystem modelling at the University of Reading, is equally sceptical about herd immunity to Covid-19 being built up — not least because it appears that the lockdown has stopped most people being exposed to the virus.
‘Although we have no confirmed idea of how many people have developed immunity, the numbers seem far too low for any kind of community-level of resistance to have been developed,’ he told Good Health.
Indeed, the World Health Organisation reported earlier this month that studies indicate only about 3 per cent of people have been infected so far with Covid-19.
‘Lockdown does not eradicate the virus from the population,’ warns Dr Roy. ‘The moment you lift the lockdown, virus transmission returns. My statistical modelling suggests that a second wave will be more serious, because while the first wave was brought in by only a few travellers from abroad, for the second there will be significant numbers of already-infected people in the UK to spread it in the population.’
As for when that second wave will strike, Professor Carl Heneghan, an epidemiologist at the University of Oxford, told Good Health he’s now certain that it will come this winter.
As for when that second wave will strike, Professor Carl Heneghan, an epidemiologist at the University of Oxford, told Good Health he’s now certain that it will come this winter
‘We know that other coronaviruses tend to be seasonal and that respiratory infections in general tend to be seasonal,’ he says.
‘Moreover, the available evidence suggests that warm temperatures and humidity suppress the virus.
‘You can see this by comparing the low infection levels in warm Australia and New Zealand [which last week declared it had almost eliminated Covid-19], with spiralling ones in cold New York and London.
‘Some 75 per cent of Covid-19 deaths are in Northern Hemisphere countries at the moment,’ adds Professor Heneghan. ‘The most plausible explanation is that the contagion is operating in a seasonal way. This was also noted in 2002 with the outbreak of SARS [a similar virus].
‘This means that the virus may disappear in July in the Northern hemisphere. As with Spanish flu, it may flip-flop between the Northern Hemisphere and the Southern Hemisphere — going south in our summer and coming back again in winter, following the pattern of the cold seasons.’
Professor Heneghan is urging UK authorities to begin opening up the economy as soon as possible to help fight a second wave.
‘We should be responding with speed to get society going,’ he says. ‘I would be opening up sooner rather than later. If our economy is failing as we go into winter, we will have fiscal and logistical problems fighting the virus’s resurgence.’
To facilitate an early exit from lockdown, Professor Heneghan stresses that the Government must rapidly increase its rates of testing and contact tracing (which starts by contacting anyone who tests positive for Covid-19, then following up everyone that person was in contact with, and then testing them, too).
An NHS app to do the job is to be tried out initially in the Isle of Wight, with every resident there to be asked to download it this week before it is launched nationally. However, it is not without issues — some have concerns that it may breach people’s right to personal privacy, as the Government will have a database on every user’s whereabouts.
The app works by automatically creating a list of the people we come into contact with, using the signal on our smartphones to identify other phones nearby. If one of the people on that list becomes identified as infected, the app should notify us immediately.
Meanwhile, the prospect of a winter second wave brings another peril: that it may coincide with the flu season. Both epidemics occurring simultaneously could put ‘unimaginable strains’ on healthcare systems, Robert Redfield, director of the U.S. health protection agency, the Centres for Disease Control and Prevention, has said.
Professor Heneghan says that while NHS leaders must urgently plan for the second wave of Covid-19, he adds: ‘We must also acknowledge that it is very hard to predict what the second wave will be like. Viruses can attenuate and become much less serious.
‘The best thing for us to do is concentrate on what is happening, and what we can do to help victims of the present wave.’ Similar advice — that we must accept the deep uncertainty about the second wave and work within it — comes from Professor Clarke.
‘The lockdown has not put us into a different place,’ he says. ‘The virus is just as likely to spread through the population as it was three months ago.
‘You need to suppress the opportunities for the virus to spread from person to person. How that is done can only involve educated guesswork.
‘The virus has been around for only four or five months, which is a blink of the eye in infectious disease research,’ says Professor Clarke. ‘The decision to lift the lockdown can’t be evidence-based. Instead there will have to be a series of educated guesses.’
Relief from the threat of further waves of Covid-19 infection will only come in the shape of a vaccine. Until it arrives, all we can do in the shadow of the threat of the second wave of Covid-19, should this re-emerge early this winter, is to hope for the best — and prepare for the worst.
As Professor Clarke says: ‘It needs to be understood that whatever the outcomes are of leaving lockdown, they are nobody’s fault. This is what we are dealing with.’