How long will the coronavirus last? Will there be a second wave? What we know

There’s much that doctors and scientists don’t know about the coronavirus that’s infected roughly 5 million people and taken over 324,000 lives, but one thing’s for certain — we’re not out of the woods yet. While lockdown restrictions continue to lift across the US and around the world, there’s concern that a second wave of coronavirus infections could hit as people come into closer contact than they have in weeks. Coronavirus vaccines are still in early development stages.

Some public health experts say it’s too soon to reopen businesses and resume social activities, like beach-going and events, even with limited capacity. Others argue that cities must reopen to keep the economy afloat, and that protective health measures will curb the coronavirus transmission in restaurants, schools, malls and on planes. The CDC has also released guidelines to help local governments identity phases for reopening, and interim suggestions for restaurants, schools and industry.

The full extent of short-term 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 government leaders would respond to a surge in coronavirus infections, though some, like Germany’s chancellor Angela Merkel, have signaled that they’ll reinstitute lockdown measures as necessary. 

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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What defines a ‘second wave’ of an illness? 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 shrinking in other parts of the country and most of the world, signaling a possible end to the first “wave” of the pandemic. If and when infection rates 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.

Read more: 7 things to not do when coronavirus lockdown and quarantine end

A wave might be made of smaller ripples

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 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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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 Centers for Disease Control and Prevention, 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. 

A recent 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. The recent 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. 

Could the second wave be worse than the first one?

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, if those came to be, 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.

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, like Singapore, Hong Kong, the Japanese island of Hokkaido and some areas of China, lockdown measures have been reinstated to combat a second instance of rising infection rates. 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.