Will There Be a Second Wave of Coronavirus—and How Bad Could It Be? Here's What Doctors Say

Over the past week, several nations and US states have announced plans to start relaxing coronavirus restrictions. But there's a big risk to opening up too soon—it could spark a second wave of coronavirus infections, warned Centers for Disease Control director Robert Redfield, MD.

Dr. Redfield believes this second wave could be even more dangerous. Speaking to The Washington Post, he said there is a possibility that "the assault of the virus on our nation next winter will actually be even more difficult than the one we just went through," because it will happen during flu season.

A second wave of disease outbreak happened with the 1918 influenza pandemic, which killed more than 50 million people in total. That pandemic experienced three waves, and the second wave was more deadly than the first. Later flu pandemics have also had multiple waves, including the 2009 H1N1 influenza, which started in April of that year and had a second wave in the fall.

Many experts agree with Dr. Redfield that a second wave of the coronavirus is inevitable. "This is an efficiently spreading human virus and it will not disappear without a vaccine," infectious disease expert Amesh A. Adalja, MD, senior scholar at the Johns Hopkins Center for Health Security in Maryland, tells Health.

It's important to distinguish between second waves and secondary peaks; they're technically not the same. "Think of it as being at the beach. The wave is coming in and after it peaks at its highest level, it comes down and crashes on the beach—it is where the state sees their highest numbers and starts to decline," public health expert Carol A. Winner, MPH, who has directed several federally funded community health-based initiatives and founded the Give Space movement in 2017, tells Health. "The second wave? Think of it as literally a second wave, it comes in behind the first, doesn't get that high, but ebbs and flows."

Those "ebbs and flows" depend on the success of protective and preventive measures, Winner adds, such as healthy hygiene habits and social distancing. These help reduce the threat of a second wave—but Winner warns that they should be strictly enforced in every state, along with rigorous testing to identify the "hot spots" in the country.

"Only then do we have a shot at isolating cases and employing the best protective measures to see a decrease," says Winner. "This will allow us to potentially loosen up state restrictions." Without sustained social distancing enforcement and quality testing, the easing of restrictions—even with the best of intentions—will increase the risk of non-immune people being exposed to infectious people.

Watching what is happening in other countries proves how virulent the new coronavirus is and can offer predictions for the US. While China has been seemingly successful in controlling the outbreak in Hubei province, the epicenter of the original outbreak, they've had an increase in cases in the north. After reporting near-zero local transmissions over several weeks, a new batch of COVID-19 cases in the city of Harbin, at the border with Russia, has resulted in fresh lockdowns, reported the Financial Times.

Singapore, too, has seen a sudden resurgence in coronavirus infections, despite being praised for its early control efforts. Although the disease has come back in cramped migrant worker dormitories, where hygiene practices and nutrition are poor, it shows just how quickly the disease can return where people are in close proximity.

It's still too early to identify COVID-19 patterns, though Dr. Adalja believes the biggest threat of a second wave appears to be during fall, which is the start of flu season. He warns that a vaccine won't be ready before then, even in the best case scenario. "A second wave starting in the fall could occur mixed with the flu and prove to be especially challenging for hospital systems to cope with," he says.

"We don't fully know why the flu is more common during the fall and winter, but we do know it's a time where people are closer together, and it's wet and cold, which may have an impact," says Winner. "Flu seems to be more common in other countries during rainy seasons. We do know that the morbidity and mortality rates can be compounded by these viruses as we move into flu season with high numbers of coronavirus cases."

Urvish Patel, MD, MPH, a public health professional in the neurology department at Mount Sinai Hospital, New York, is hedging his bets on a second wave. He points out that other SARS and MERS viruses have not shown a second wave, but says we should be ready for any possible conditions. He advises that "prevention and precaution" is always the best approach.

"Countries can't be kept on lockdown for prolonged periods of time due to economic burden and also the psychological impact of staying at home, but residents need to strictly follow social distancing until herd immunity from COVID-19 via mass immunization is achieved," Dr. Patel tells Health. "This is unlikely to happen for another six to 12 months."

At the same time, he believes the lockdown shouldn't be lifted until mass testing is carried out, plus self-quarantining at home with proper treatment for those who test positive (or have symptoms, in the absence of a test). "Businesses should start sending their employees for medical tests frequently. Scanning individuals daily for symptoms will be the best way to move forward and the government should do the same by taking care of public places."

Until we get to that point, Dr. Patel says it's crucial to continue frequent handwashing, not touching your face, cleaning surfaces often, and using a mask and gloves to protect yourself when you're in a public place. And, of course, follow social distancing guidelines.

"On a community level, we need to ramp up testing for asymptomatic people," Dr. Patel adds. "Our health care providers must be protected so they can do their jobs and stay safe themselves. Strengthening the hospital system to treat symptomatic patients will help to reduce mortality until we have a proven treatment or vaccine."

The information in this story is accurate as of press time. However, as the situation surrounding COVID-19 continues to evolve, it's possible that some data have changed since publication. While Health is trying to keep our stories as up-to-date as possible, we also encourage readers to stay informed on news and recommendations for their own communities by using the CDC, WHO, and their local public health department as resources.