A second wave of coronavirus: When it could come, how long it could last and more - CNET

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Experts warn that coronavirus infections could begin to increase as businesses begin to reopen and stay-at-home orders slowly lift.

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For the most up-to-date news and information about the coronavirus pandemic, visit the WHO website.

Experts are bracing for a second wave of the coronavirus Exactly when it will happen, how it will happen and if we're already starting to see the effects are still unknown. But scientists, health officials and government leaders around the world have warned that new COVID1-19 cases could surge as lockdown restrictions lift and people come into closer contact with one another than they have in weeks. Because the coronavirus is a highly contagious pathogen that spreads through breath and saliva, experts are urging lawmakers to be on the lookout for a second "peak," a sharp increase in cases that falls short of a full-blown second "wave."

There's still much that doctors and scientists don't know about the coronavirus that's infected nearly 6 million people and taken almost 400,000 lives, but most experts agree that until we have an effective coronavirus vaccine, the only way to slow the spread of the virus is by taking precautions like social distancingwearing face masks in public and washing hands correctly and frequently.

Even so, some public health experts say it's too soon to reopen businesses and resume social activities, such as going to the lake or beach and visiting amusement parks, even with limited capacity. Others argue that cities must reopen to keep the economy afloat, and that protective health measures will curb coronavirus transmission in restaurants, schools, malls and on planes. The Centers for Disease Control and Prevention have also released guidelines to help local governments identify phases for reopening, and interim suggestions for restaurants, schools and industry.

Keep track of the coronavirus pandemic.

The full extent of short- and long-term effects of the coronavirus and the COVID-19 disease it causes are still unknown, including how long you may be immune after you recover and if it's possible to become reinfected. It also isn't clear how governments would respond to a surge in coronavirus infections, though some countries, such as Lebanon and South Korea, have already reinstated lockdown orders in areas where the virus seems to be reemerging.

This story provides an overview to help keep you informed of the current discussion. It will update frequently in light of new and changing information provided by health officials, global leaders and the scientific community, and is not intended as a medical reference. 

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When could the second wave of coronavirus hit?

As countries and states begin to ease lockdown restrictions, health officials around the globe are already on the lookout for rising infection rates that could signal a second wave of coronavirus-related illness. Most public health experts -- including the Director of the CDC, Dr. Robert Redfield, and Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Disease -- anticipate the next big uptick to happen this fall or winter.

Why then? Flu cases tend to drop off during the summer, which has led some health experts to hope COVID-19 cases go down when the weather gets warmer as well. Dr. Amesh Adalja, a pandemic preparedness expert at Johns Hopkins University, told the Los Angeles Times that other coronaviruses don't fare well during summer months because, once outside the body, both the hotter temperatures dry them out and the ultraviolet light from sunnier weather affects them. 

study published in the Canadian Medical Association Journal, however, offers data to suggest that this particular coronavirus, SARS-CoV-2, seems impervious to temperature differences and only slightly affected by humidity. An outbreak in Mumbai and Indonesia's ongoing struggle to contain the virus highlight how the pandemic is affecting countries across climate zones, including many regions at or near the equator. 

It may be that fall and winter upswings could occur as a result of economies reopening and people coming into closer contact, transmitting the infection anew, but that reasoning is pure speculation and not the result of scientific study. We'll need to wait to see what actually transpires. 


Different parts of the country are lifting lockdown orders at their own pace, including deciding when to open nonessential businesses.

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What's a 'second wave' anyway? Can there be more?

Generally speaking, a "wave" in a pandemic is a period of increasing disease transmission following an overall decline. Currently, although cases of the coronavirus continue to increase in some parts of the US, rates of new infections appear to be declining in the country overall. That same mix of upward and downward trends can be seen globally, prompting executive director of the World Health Organization Mike Ryan to estimate that we are "right in the middle of the first wave." If and when infection rates have declined across the board, then begin to climb again, that will indicate the next or "second wave." The longer the pandemic goes on, the more waves are likely to occur.

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A wave might be made of smaller ripples or 'peaks'

The coronavirus pandemic hasn't affected all parts of the country in the same way or at the same time. Cities and states went into lockdown and quarantine at different times, and that's also how the country is starting to get out of it, with different areas easing restrictions in phases and at their own pace.

Some health experts have warned the lack of a unified reopening plan might help spread the coronavirus and could actually fuel a second wave as people travel from the hardest hit areas to places with far fewer infections. Ali Khan, a former CDC official, said a second wave might comprise many simultaneous, smaller outbreaks that, taken together, seem more like a singular wave.

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Spikes in new coronavirus cases have already been documented in areas emerging from lockdown. Wisconsin, for example, experienced its biggest single-day increase in new infections and deaths exactly two weeks after the state Supreme Court overturned the governor's stay-at-home order. Georgia, which was one of the first states to start lifting lockdown orders, is beginning to see an uptick in new cases after several weeks of plateau.

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Although some experts hope the coronavirus, like many other viruses, dissipates during hotter, sunnier weather, new research suggests temperature does not affect the virus. 

Patrick Holland/CNET

Could the second wave be worse than the first?

If there is a second coronavirus wave, the severity of the outbreak would depend on multiple factors, like how well people maintain social distancing and how many people wear face masks. The widespread availability of tests might also play a role, in addition to contract tracing for anyone who tests positive. 

For example, a recent study and computer model developed under De Kai, a computer scientist with appointments at both the University of California at Berkeley and Hong Kong University, proposes that if 80% of the population wore face masks in public, coronavirus transmission rates would plummet (PDF) to about 8% compared to wearing no masks.

Basically, the more measures there are in place to help reduce disease transmission -- and the more effectively those measures are followed -- the lower the infection rate may be the second time around, according to the computer model. 

Other factors that could come into play are any potential genetic mutations in the coronavirus that could make it more or less transmissible, the development of an effective vaccine, the development of safe, effective treatments for the COVID-19 disease and the ability to test a large number of the population, even people who don't appear to be sick.


Most experts agree that widespread testing will be necessary to help curb outbreaks while we wait for a coronavirus vaccine. 

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Will there be another lockdown?

It's possible. Decisions about future quarantines are up to government leaders working with health officials, but there is an indication that the need could occur. 

In some parts of the world that have experienced a second wave of coronavirus infections after lifting lockdown restrictions, such measures have been reinstated. About a month ago, Singapore, Hong Kong, the Japanese island of Hokkaido and some areas of China all brought back lockdown measures to combat a second instance of rising infection rates. More recently, Lebanon and South Korea have brought back such orders as well.

Until there's an effective vaccine, it's possible that different parts of the world will see fluctuating degrees of lockdown as governments adjust their response in the ongoing battle against the coronavirus.

Perhaps the most pressing questions of all are what a second wave of coronavirus might mean for you. Here's how we think life will look after quarantine ends as the public braces for a second wave. If you do have to leave the house, here are some practical ways to stay safe when you go out. Finally, don't unlearn all the good habits you've developed during the pandemic -- like frequently washing your hands.

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