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Learning from the past - The second wave of the 1918 “Spanish” flu pandemic a century ago was much deadlier than the first, and many are fearful of history repeating itself.

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What is a second wave? - The BBC spoke to Dr. Mike Tildesley, from the University of Warwick, who explained that there is no formal definition of a wave, but that many actually mistake a bumpy first wave for a second wave.

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What has to happen before a second wave -

To identify a second wave, the virus would first have to be brought under considerable control with a substantial drop in cases.

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The first wave typically has three stages -

Going off historical information from past pandemics, there are three stages: the outbreak, the peak, and the fall, resembling a bell curve.

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Then comes a second sustained rise in cases -

A second wave begins after, with a sustained rise in infections. Places like New Zealand and Beijing, who had many consecutive virus-free days, can’t be classified as experiencing a “second wave” when a small number of new cases appear.

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The "end" could be a new beginning - Countries can use a mathematical model known as SIR (susceptible, infected, recovered) that's used to predict the “end” of coronavirus by calculating the projected spread and recovery of the disease.

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The moment of relaxation is most dangerous -

Ironically, the people who should be worried about a second wave are those who seem to be nearing the clear, who are comforted by falling numbers of cases.

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Second wave triggers -

The biggest trigger for a second wave is lifting lockdown restrictions. The difficulty is that lockdowns, while being our best defense against the virus, have caused massive disruption, from jobs to mental health to schooling, and more, as well as the fact that people may take things too far.

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Don’t drop your guard -

Cities will try to reopen as soon as possible to help the economy, but as a previously confined population rushes prematurely back into “normal,” the virus will inevitably rise again.

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It’s already happening -

Many cities have already experienced this resurgence of infections as a direct response to lifted restrictions, though most were not yet out of the clear with the first wave.

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Underestimating the virus -

The public confusion on whether asymptomatic cases can be infectious, whether you can get the virus twice, who is susceptible, and how the virus spreads are all factors that increase the likelihood of a second wave.

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False reliance on a vaccine -

While the vaccine is in the works, there is no guarantee of when it will be available, with many estimates placing it at 2021 at the earliest.

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False information from world leaders - Politicians causing what WHO calls an “infodemic” are making dangerously false statements about the virus, including ideas about bleach injections, refusing to wear a mask, and telling people to resume their daily schedules. Their words are directly influencing the number of cases.

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Strategies in place - Fear of the second wave is why restrictive measures are typically being lifted in stages. It’s also why other tactics are being put in place while restrictions are being lifted, like contact tracing or mandatory face coverings.

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It will look different for every country -

Each country has its own factors that contribute to the spread and shape of the virus, including the state of their health systems before the pandemic arrived. The shape of the virus waves are a reflection of what's happening in each society.

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Can a second wave be more dangerous? -

Fortunately, many experts say a second wave can’t be as dangerous as the first simply because we know much more about the virus now, and we’re equipped with strategies to slow the spread.

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A second wave will likely not be so large -

The value of R—the average number of people each infected person passed the virus to—was 3 at the start of the pandemic, which was very fast. Since then, it has dropped all over the world.

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A second wave will likely not be so large - The BBC reported that even countries facing the highest numbers of coronavirus cases, like Brazil and India, don't have an R of 3.0.

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When could it happen? -

Though it varies greatly around the world, many are worried that winter may be a dangerous time, as other coronaviruses spread more readily during that season.

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What can governments do? -

Another lockdown is the most immediate way to slow another surge. New Zealand has been a world leader on the COVID-19 front, and they’ve also put aside funds in case a second wave hits.

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What can you do? -

The primary way to slow the spread of the virus is to stay home as much as possible. The next option is to use a mask and socially distance at all times.

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The basics -

Wash your hands, sanitize high-touch objects like your phone, wear a mask when you leave the house, and avoid touching your face.

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Strengthen your immune system - The more equipped your body is to fight off harmful bacteria, the less likely you are to catch and spread it. There are plenty of things you can eat and do to boost your immune system.

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Support small businesses carefully - Small businesses are only opening prematurely because they’re in dire need of money or else face collapse. You can help them by ordering locally and tipping well.

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Work from home if you can - Most of the traffic in the world consists of people going to and from work, which poses an especially dangerous risk with public transit. If you can work from home, that’s one surefire way to lower the risk of unnecessary spread.

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Limit your bubble - Loneliness is a real detriment to mental health, but finding love in the age of COVID-19 is a risk you’ll want to really think through.

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Reevaluate our own priorities - If getting a haircut feels important and harmless in the moment, imagine everyone having the same idea as you. If we don’t want the virus to spread, we all have to take individual steps, since we can’t control the behavior of others.

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Perspective -

No one wants to give up their daily comforts and routines, but we have to think in the long-term. The more we temporarily give up now, the faster we’ll be able to return to those daily comforts and routines once again. If not, we may all face a second wave.

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See also - How to stay safe as cities reopen

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