Intended for healthcare professionals


Sixty seconds on . . . waves

BMJ 2020; 370 doi: (Published 03 August 2020) Cite this as: BMJ 2020;370:m3074

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  1. Elisabeth Mahase
  1. The BMJ

The pandemic friendly greeting?

No. We’re talking about the “second wave of the [covid-19] pandemic” that Boris Johnson said shows signs of coming to Europe, which caused a tsunami of protest after he announced new travel restrictions for people coming to the UK from Spain.

Batten down the hatches!

You might think of waves as peaks and troughs, but there is no set definition of a wave in terms of infectious disease. Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, said, “Much of the thinking about second waves is derived from previous influenza epidemics and pandemics, and the patterns may not be the same for covid-19: SARS-Cov-2 is a very different virus to the different influenza viruses.”

Can you shore up the facts?

It’s not plain sailing. When people talk about waves they often refer to the 1918 “Spanish flu” pandemic, which reportedly killed 20-50 million people and is talked about as coming in four waves, the second wave being the most deadly. However, experts from the University of Oxford’s Centre for Evidence Based Medicine have noted several problems with the evidence.1 “The true number of deaths from ‘Spanish flu’ is highly uncertain,” they said. “It is not clear, for instance, if they were actually caused by influenza, which was not a reportable disease at the time and what role bacterial superinfection played. Estimates are, therefore, educated guesses.”

Surf’s up?

Things certainly look choppy. Some countries and regions—such as Leicester in England and Beijing in China—have recently seen spikes in cases, but these are all believed to be part of the same wave and a predictable outcome of easing lockdown restrictions.

So, Johnson’s a loose cannon?

You’ll get me in deep water. But, while the UK prime minister seems certain that a second wave is approaching, the World Health Organization has said that it’s actually “one big wave.” Margaret Harris, WHO spokesperson, said, “People are still thinking about seasons. What we all need to get our heads around is that this is a new virus and this one is behaving differently . . . It’s going to be one big wave. It’s going to go up and down a bit. The best thing is to flatten it and turn it into just something lapping at your feet. But at the moment, first, second, third wave—these things don’t really make sense.”

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