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Sunday, March 3, 2024

Don't Talk About Covid-19’s ‘Waves’—This Isn’t the Spanish Flu

Since the pandemic began, the threat of a second, deadlier wave of coronavirus has captured the public imagination. The fear, which provokes viral Facebook posts and influences government strategy, is that this pandemic will follow a trajectory similar to that of the 1918 Spanish flu. Two-thirds of the 50 million who died would do so from October to December 1918, during a so-called “second wave.” But this fear may be misdirected. The world is still yet to hit the peak of the first wave. And, until we get a vaccine, it likely never will.


Across the world, the pandemic is still accelerating. The first case was reported in China in late December. It took three months from that date to reach 1 million cases. The leap from 12 million cases to 13 million cases took just five days. A Reuters tally puts the total number of dead at 570,000. Daily deaths peaked in mid-April at 10,000 a day; since then they have hovered around the 5,000 mark.

Countries continue to break grim records. In Latin America, where the disease is accelerating fastest, Brazil reported another 24,000 cases on July 12, bringing its total to 1.87 million. India, initially successful at containing the virus, reported a record spike on July 11—27,114 new cases—taking the national total to more than 800,000.

In the world’s worst-hit nation, the United States, 20 states and Puerto Rico reported a record-high average of new infections over the past week, according to The Washington Post. Five states—Arizona, California, Florida, Mississippi, and Texas—also broke records for average daily fatalities in that period. The US total is now more than 3,290,000 cases and 132,000 deaths. “In most of the world, the virus is not under control,” WHO director-general Tedros Adhanom Ghebreyesus said last week. “It is getting worse.”

While the spread of the virus in each country will be driven by a variety of factors, the one thing that links high infection and death rates is the severity of a country’s interventions—its school and work closures, restrictions on international and domestic travel, bans on public gatherings, public information campaigns, as well as testing and contact tracing. Researchers from the University of Oxford collected daily data on a range of containment and closure policies for 170 countries from January 1 until May 27. The findings were conclusive: The earlier and harsher a country’s lockdown, the lower its eventual death toll. “The case is closed in terms of how best to contain this,” says Amitava Banerjee, associate professor in clinical data science at University College London. “The less stringent your measures, the more deaths you have, by a country mile.”

Easing these lockdowns has proven challenging—nations that previously had the outbreak under control have reported new outbreaks. Israel, for instance, reported almost 1,000 new cases on July 5 and had to reimpose restrictions. South Korea has reported several new infection clusters stemming from nightclubs and offices.

The importance of government intervention may explain why the virus hasn’t yet ravaged lower-income countries. “One of the reasons that some low-income countries have had relatively lower cases is because they followed the advice better,” says Banerjee. He gives the example of Dharavi in Mumbai, India, which is one of Asia’s largest slums. “Compared with any metric on the planet, it is terribly deprived, but it had relatively fewer cases and a lower mortality rate,” he says. The reason? People wore masks, and the authorities implemented an aggressive test-and-trace system alongside use of GPS and CCTV surveillance.

Lower-income countries also have younger populations, for instance, who are generally at lower risk of hospitalization and death. The timing of when the epidemic reached a country will also have an effect. “If for example, the virus was in Europe in January, we didn’t see the big outbreaks until March—it took three months for the infection rate to be high enough to be noticed in hospitals,” says Martin Hibberd from the London School of Hygiene and Tropical Medicine. As a result, some countries with relatively few cases right now may be at the very start of their first wave.

These disparities between nations mean that it may not be appropriate, at a global level, to think in terms of waves. The concept assumes that all countries are at similar stages of the pandemic, and that the data we have on the virus’s progress is accurate. This, of course, isn’t true—neither transmission nor data about this transmission are synchronized between countries. The UK, for example, only tests those displaying symptoms, and while the infection rate may be plateauing, it hasn’t fallen to single or double figures as in New Zealand and Iceland.

“I think waves are a useful concept for individual countries or in the regions of countries, but it’s not a very useful concept about the world’s progress,” says Hibberd. “If you think about influenza, we don’t call it waves when it comes back every year—we call that seasonal flu.”

Because of this, we will likely never see a global second wave, but rather a series of localized flare-ups. International travel will be disrupted almost indefinitely, and nations will fall in and out of favor as holiday destinations depending on their grip on the virus. In January, you wouldn’t have wanted to travel to China; now, it is one of the safer destinations.

Then there are other countries, like the US, that have never been in control. Speaking about waves in this context is currently nonsensical— infection rates need to go way down before they can rise again in a second wave. “In the United States we are not seeing anything that I would consider to be a second wave,” says Loren Lipworth-Elliot, an epidemiologist at Vanderbilt University in Nashville, Tennessee. “We are definitely in the first wave, if you want to call it a wave—it’s just a long, lingering epidemic.”

Keeping the virus under control over a prolonged period of time is key. A report from the Academy of Medical Sciences, commissioned by the UK’s chief scientific adviser, Patrick Vallance, has warned that coronavirus infections could grow “out of control” this winter. That second spike could cause 120,000 deaths in a worst-case scenario.

But not every country needs to end up like the US. The spiraling rate of infection is the result of a botched governmental response, not an inevitable trajectory. Nor is it likely that the infection rate of the second wave will ever reach the ferocity of the first. The 1918 flu pandemic is misleading in this sense. We are far more vigilant about public health than we were 100 years ago—or even six months ago. “In that instance the second peak was worse than the first,” says Nicola Stonehouse, professor of molecular virology at the University of Leeds. “That’s where that worry comes from. But we are in a different position now.”

This story originally appeared on WIRED UK.

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