Will There Be a Second Coronavirus Wave?
Overall, it doesn't look like the first wave of Covid-19 is over, and a second coronavirus wave looks likely, according to experts.
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With so many coronavirus surges, spikes, peaks, and valleys all over the United States, it’s hard to know exactly where the country is in the arc of the Covid-19 pandemic and, importantly, whether or not there will be a second wave. Johns Hopkins University, which tracks Covid-19 numbers globally believes that the nation is still in the first wave, even though some states like New York and New Jersey are seeing declines in cases and/or deaths. Robert A. Phillips, MD, PhD, chief physician executive at Houston Methodist, not only believes we are in the first wave, but that a second wave is almost certainly inevitable. A person who tests positive for Covid-19 infects, on average, three more people and we still have community transmission in many areas. “It’s just biology,” he says. “That’s just going to happen.”
Here’s what you need to understand about first waves, second waves, and the surges and spikes in between during the novel coronavirus.
What is a wave?
The answer is a little unclear. “It’s not really a well-defined term in epidemiology,” says Loren Lipworth, professor of medicine in the division of epidemiology at Vanderbilt University Medical Center in Nashville. Generally, a wave would consist of a rise in new cases followed by a period of relative calm with fewer or no new cases, explains Aaron Glatt, MD, a spokesperson for the Infectious Diseases Society of America.
New Zealand, which had more than 100 straight days of no new coronavirus cases, would seem to be a good example of a clear first wave. And even though there have been a small number of cases recently, the first wave may end up being the only wave in that country, which quickly implemented strict control measures. With the 1918 pandemic, there three or four distinct waves where cases faded away before rising again, explains J. Alexander Navarro, assistant director of the Center for the History of Medicine at The University of Michigan.
Waves that surge
“We think the wave is over when the infection rate of those tested is well under five percent,” explains Dr. Phillips. Because a first wave can seesaw up and down, experts break waves into surges; this means Houston and many parts of Texas are technically in wave 1, surge 2 of the Covid-19 pandemic, he says. An August 13 paper in the Journal of the American Medical Association co-authored by Dr. Phillips documented first and second surges of coronavirus at Houston Methodist. The first surge occurred between March 13 and May 15 and the second between May 16 and July 7, with the second starting two weeks after a phased statewide reopening.
Another important metric, says Dr. Lipworth, is the number of cases per 100,000 people per day. Most schools could safely reopen if that number is under 10, she says. According to the Harvard Global Health Initiative, 18 states are within this parameter. Georgia, which has reopened some schools, leads the pack with 33.8 new cases per 100,000 population. (Learn what experts are doing to protect their kids from getting Covid-19 at school.)
Factors that drive waves
In 1918, slight mutations in the circulating influenza virus may have played a part in successive waves, says Dr. Navarro. But in the current crisis, virus behavior is not driving the ups and downs: Human behavior is, says Dr. Lipworth. In other words, not wearing masks, not socially distancing, and not washing hands are pushing numbers up, or at least not allowing them to go down. These measures work because Covid-19 spreads largely through droplets when people are in close contact, says Dr. Navarro.
Experts have noted mutations in SARS-CoV-2, the virus that causes Covid-19, but not ones that would significantly impact either how fast and well it travels or how lethal it is. Learn more about how Covid-19 is mutating.
The impact of schools reopening
Actually, we’ve already seen the impact, says Dr. Phillips: More cases. In areas of the world where schools reopened successfully, positivity rates were less than five percent, says Dr. Lipworth. “No matter what you do within the walls of the schools, if you have high levels of community viral transmission, that doesn’t bode well for a safe school reopening,” she says. (These are the best face masks for kids returning to school.)
Dr. Phillips agrees. “I think you need to have infection rates in a community under five percent to open up schools,” he says. “Kids are not going to socially distance, they’re not going to wear their masks.” (Here’s how to have the coronavirus talk with your kids.)
Children do get sick
Even though children may not get as sick as adults and, especially older adults, they do get sick from Covid-19 including a frightening multi-system inflammatory syndrome in children (MIS-C). “The impact is not going to be zero, says Dr. Navarro. And they can transmit the virus to others.
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Other opportunities for spreading Covid-19
Schools don’t provide the only opportunity for the virus to travel. Any example of people coming together, especially a lot of people and especially in tight spaces, is going to be bad. That means not just bars and restaurants but, as an August 5 in the International Journal of Infectious Diseases points out: Coronavirus transmission can occur at family gatherings, transportation, in shopping malls (holiday shopping season is coming up), tourist gatherings, conferences, religious settings, prisons, offices, and nursing homes. This is also why there’s so much debate about sporting events, which typically attract large crowds, not to mention the close proximity of the players in sports like football.
“Large gatherings is definitely the most likely way in which viruses spread,” says Dr. Lipworth. “That family gathering of 20 people in the backyard seems to be relatively safe, but one person who has Covid-19 in that situation can lead to a rapid increase in transmission.”
So where are we in the wave cycle?
The United States does not have one wave or surge, it has hundreds or more depending on the state, the county, the city, even the facility. “You have to look at each state separately, not the whole country. Even in New York City, there are regions within a region,” says Dr. Glatt, who is also chairman of medicine and hospital epidemiologist at Mount Sinai South Nassau and professor of medicine at Icahn School of Medicine at Mount Sinai in New York City.
Some areas, like New York, may be approaching the end of their first wave. New York State has only 3.2 new cases per 100,000 population—fifth lowest in the country. But they have lessened restrictions and Dr. Phillips says he would not be surprised if they saw an increase. California did a good job of flattening the curve and getting towards the end of a first coronavirus wave, but now the state is seeing large numbers again. Other places seem to be right smack in the midst of that first wave—Georgia, Florida, Mississippi, Alabama. There doesn’t seem to be anywhere in the country that is over this first wave, says Dr. Phillips.
How can we prevent a second coronavirus wave?
It’s not clear that we can prevent a second coronavirus wave at this point but the way forward is no mystery: A clear, consistent message on social distancing, wearing a mask, and washing your hands, and people’s willingness to take heed, says Dr. Glatt. This would also decrease spread across borders.
It comes back to the “3 W’s,” says Dr. Phillips: Wear a mask, wash your hands, and watch your distance from others. Which is not very different from what people were doing during the influenza pandemic of 1918, says Dr. Navarro.
Getting back to pandemic basics
It worked in 1918, and it works now. “You have to give people credit for what they did in the spring,” says Dr. Phillips. “There was a marked decrease in travel. People did stay at home. There was clear messaging [from leaders] and people actually did participate and we did flatten the curve.” Now we have to keep doing it.
- Johns Hopkins University: "Coronavirus COVID-19 Global Cases"
- Johns Hopkins Medicine: "First and Second Waves of Coronavirus"
- Robert A. Phillips, MD, PhD, chief physician executive, Houston Methodist
- Loren Lipworth, ScD, professor of medicine, division of epidemiology, Vanderbilt University Medical Center, Nashville
- Aaron Glatt, MD, spokesperson, Infectious Diseases Society of America (IDSA), chairman of medicine and hospital epidemiologist, Mount Sinai South Nassau and professor of medicine, Icahn School of Medicine at Mount Sinai, New York City
- Business Insider: "New Zealand has now gone 100 days with no new local COVID-19 cases—and it hasn't been on lockdown since June"
- J. Alexander Navarro, PhD, assistant director, Center for the History of Medicine, The University of Michigan, Ann Arbor
- Journal of the American Medical Association: "Characteristics and Outcomes of COVID-19 Patients During Initial Peak and Resurgence in the Houston Metropolitan Area"
- Harvard Global Health Initiative: "How severe is the pandemic where you live?"
- International Journal of Infectious Diseases: "Cluster infections play important roles in the rapid evolution of COVID-19 transmission: a systematic review"