A Second Wave of Coronavirus: Is It Here, How Long Could It Last?


Coronavirus cases are surging. Are we in a second wave, or is this still the first?

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

Health experts have been warning of a possible second wave of coronavirus for months. As coronavirus cases top 8 million globally and new cases surge across the country and around the world, some doctors and scientists say the second wave is already upon us. But others caution that this recent uptick, which many attribute to loosened lockdown restrictions and people not following social distancing protocols, is not evidence of a second wave, but rather a continuation of the first. 

On Friday, Dr. Anthony Fauci, the director of the National Institute of Allergy and Infectious Disease, told CNN the current surge in new coronavirus cases is not a second wave. He added that a second wave in the fall, which many experts, including Fauci himself, have predicted, is "not inevitable."

Here are some recent developments:

Read on for more details about what a second wave of the virus might entail and what the experts say. 

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. 

What are the effects of reopening the economy on coronavirus cases?

For public health and medical experts, the correlation seems high, even "totally predictable." Others posit that in addition to people coming into close proximity, the virus might be "catching up" to populations that had previously been uninfected.

Public health experts have warned that 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 have argued 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.

Part of the problem is that 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. 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.

Why has the second wave of coronavirus been linked to fall?

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 -- have said they anticipate a big uptick to happen this fall or winter.

A new model also suggests an increase in coronavirus-related deaths this September, CNN reported.

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. Early outbreaks in Mumbai and Indonesia's struggle to contain the virus highlight how the pandemic is affecting countries across climate zones, including many regions at or near the equator. 

Current cases are soaring in Arizona, where major cities reach triple-digit temperatures in June, as well as rising cases in Florida, also counter the suggestion that heat may suppress the coronavirus' transmission.

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. 

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 WHO Executive Director Ryan to estimate in late May 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.

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.

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.

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, including 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 study and computer model developed under Dr. 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.