As a succession of states have noticed a troubling rise in COVID-19 cases over the past few weeks, the Trump administration has become more vocal in countering claims that the nation needs to brace for a so-called "second wave."
Last week, Larry Kudlow, the White House economic adviser, proclaimed on Fox News that the uptick in cases "is no emergency and there is no second wave." This week, Vice President Mike Pence echoed that sentiment in a Wall Street Journal op-ed titled, "There Isn't a Coronavirus 'Second Wave."
"The media has tried to scare the American people every step of the way, and these grim predictions of a second wave are no different," Pence wrote.
Pence and Kudlow may be correct to assert that the country is not entering a second wave, but only, experts said, because this is still the first. A consensus of epidemiologists believes the risk of a second wave remains real, but will likely come in the fall. And because the potential for the virus to expand its reach remains a significant cause for concern, they said this is no time to relax preventive measures such as social distancing, hand-washing and mask wearing.
"We are in the first wave, but we are in the second inning of a nine-inning game," said Dr. Michael Osterholm, an epidemiologist at the University of Minnesota.
The issue may come down to a semantic misunderstanding, Osterholm said. When epidemiologists describe a second wave, they are referring to a reemergence of the virus after a quieter period of minimal transmission.
"A wave occurs when you see an increase in cases and then a subsequent decrease in cases with a trough," Osterholm explained. "Then the second wave occurs when you come out of that trough and goes into another large number of cases -- often more so than the first wave."
Others agreed. Dr. Vincent Racaniello, a Columbia University virologist, told ABC News that many expect cases to decline over the summer months, then flare up again in the fall.
"In the cooler months, with lower humidity, the virus transmits better so we see outbreaks of respiratory infections in those times," Racaniello said. "I think that's what COVID-19 will be like in the fall."
Dr. Ashish Jha, general internist and director of the Harvard Global Health Institute, warned that "as schools come back along with universities and workplaces, we're all very worried we're going to see big spikes in cases that nationally will result in a second wave."
There is ample historical precedent for that theory. Seven of eight major pandemics since the 18th century suffered "a second substantial peak approximately six months after the first peak," according to the findings of a working group comprised of top infectious disease researchers.
The second wave of the infamous 1918 Spanish Flu pandemic, for example, drew substantially more fatalities than the initial one.
In that working group's review, published by the University of Minnesota's Center for Infectious Disease Research and Policy, experts envisioned a scenario in which "the first wave of COVID-19 in spring 2020 is followed by a larger wave in the fall or winter of 2020 and one or more smaller subsequent waves in 2021."
Advocates for the most vulnerable Americans took direct aim at Pence for his suggestion that the media has erroneously hyped a second wave. Care providers at the advocacy group LeadingAge released a video calling on the vice president to stiffen his resolve.
"After this wave, there will be another one," LeadingAge CEO Katie Sloane said in the video. "It's not over."
Sloane condemned Pence's claim in The Wall Street Journal that the federal government's response to the pandemic is a "cause for celebration" as a "startling assertion."
Dr. John Brownstein, an epidemiologist at Boston Children's Hospital and an ABC News contributor, said Pence was delivering the wrong message at a time when health officials want the public to remain vigilant against viral spread.
"There are dangers in messaging that pushes an 'out of the woods' narrative," Brownstein said. "Yes, gains have been made in public health preparedness, but we still need the support of the public to keep to reducing virus transmission."
In that vein, a collection of former American policymakers has begun sounding alarms about "pandemic fatigue" -- the emerging disregard of preventative measures that likely helped curb the disease's impact over the past several months.
"People are tired and worried about their lives and their livelihoods. But now is not the time to relax," said former Connecticut Sen. Joe Lieberman, a founding member of the Bipartisan Commission on Biodefense.
"The virus continues to spread," Lieberman said. "Until preventive measures or medical treatments arrive, we must continue to do what we can to protect one another. We need to wear masks, maintain social distancing and support science, public health and medicine."
While scientists point to the historical record to justify their concerns about a viral resurgence, leading epidemiologists are careful to note that a forthcoming second wave of the disease is not a certainty and could be managed.
"It is not inevitable that you will have a so-called 'second wave' in the fall or even a massive increase if you approach it in the proper way," said Dr. Anthony Fauci, the administration's top infectious disease expert.
Dr. John M. Barry, a Tulane University professor and author of "The Great Influenza: The Story of the Deadliest Pandemic in History," said a second wave remains dependent on whether Americans can redouble prevention efforts.
"It depends on people's behavior," Barry said. "What you're doing today has impact between two or four weeks out. It's a long way from the fall."
To Osterholm, the entire debate over whether or not we will see a second wave is premature. He said the focus now should be actively preventing the current outbreak.
"We should not get caught up in whether there's a wave or not," he added, "because that misses the whole point."
ABC News' Benjamin Siegel and Dr. Jessica Johnson contributed to this report.