“COVID is here to stay: We will be dealing with this forever.”

Two of the country’s top infectious disease experts presented a sobering look at the battle still to come against Covid-19. Their message, conveyed during a recent CNBC event, was encapsulated in related views on how much of a difference a coronavirus vaccine can make and what reaching herd immunity in the U.S. population will mean for life across the nation.

“Even with a vaccine, there is no going back to normal anytime soon,” said Thomas Frieden, former director of the Centers for Disease Control and Prevention, speaking at a CNBC Workforce Executive Council virtual event to human resources executives on July 23 about a safe return to the workplace. “Prepare for at least eight to 12 months of this situation,” said Frieden, who now runs the Resolve to Save Lives disease prevention organization.

Michael Osterholm, director of the Center for Infectious Disease Research & Policy at the University of Minnesota, said it is estimated that 7% to 9% of the total U.S. population has been infected with coronavirus, and that means the worst is yet to come. He said the best understanding in the medical field is that transmission will not slow down until 50% to 70% of the population is infected.

“The pain, suffering, death and economic pain we’ve had to date — that’s 7% to 9% of the U.S. population. We’ve got a long way to go,” Osterholm said.

For businesses and the U.S. economy, that means there will be no “V-shaped” return to workplaces.

“Most businesses in the country will be hard-pressed to operate in a way they want to schedule when we have ‘houses on fire’ in our communities,” said Osterholm. “I understand the pain and economic suffering, but I don’t see any way we get numbers down regionally. We’ve got to stop this virus activity or there will be fear we will see these peaks, but every time it goes down, it plateaus at a higher level and just comes back again. In many communities in this country, I see no way to operate as they once did.”

Cases have started to show some signs of slowing in recent hot spots across the U.S. South and Southwest, including Florida, Texas and Arizona.

In fact, both experts believe Covid-19 is here to stay.

“We will be dealing with this forever,” Osterholm said.

“Covid is here to stay,” added Frieden.

Frieden said one of the biggest issues is that the medical community still lacks good data on the disease, but he added, “Nothing we’ve seen suggests it will just go away.”

That’s why the measures being advocated that may seem like “blunt” tools, from extreme physical distancing in the workplace to remote work as the norm, are the best options we have to stop the virus. Countries that moved quickly to rapid testing and tracing and quarantine were able to get Covid-19 under control more quickly, but the U.S. is too far behind on that more precise tool, “the box-it-in strategy,” Frieden said.

If a vaccine becomes available over the next six to 12 months and we can produce enough of the vaccine for the population, there are still big question marks about its effectiveness, Frieden said. This week the first vaccine to go into a large-scale Phase 3 trial, from Moderna Therapeutics, started toward its goal of enrolling 30,000 individuals. But the scientific community still does not know how long a vaccine will be effective for, and whether immunity within elderly individuals will last. It also is not known about any side effects, as well as the percentage of the population that may refuse to get the vaccine.

“We have great vaccines and still 100,000 deaths a year from measles,” Frieden said, speaking about Africa. “In the U.S. we still have hundreds of thousands of hospitalizations from flu each year with vaccines, and it looks more likely than not that this virus keeps circulating even with a vaccine.”

Osterholm, who has studied the coronavirus class of infectious diseases around the world, including MERS and SARS, said these viruses are “notoriously famous for not granting durable immunity.” He added, “We will be revaccinating on an annual basis.”

One of the blunt tools the U.S. has been using with more frequency is a requirement to wear a face mask, including in workplaces. Research is starting to emerge showing the value of masks in protecting both wearers and those with whom they come into contact, but Osterholm said while wearing a mask is among the best advice we have today, there are problems. First, the masks where data has been strongest are the N95 masks that are used to protect health-care workers, and there is no way we can make those masks available to the general public.

“We have to save those for health-care workers,” Osterholm said, noting that in Minnesota intensive-care units for Covid-19, health-care workers are wearing N95 masks 10 days in a row.”

But he urged everyone to wear a covering.

“Face-cloth covers are not surgical or N95, but wear ‘em, wear ’em,” Osterholm said, even though he added, “We don’t know how well they work.”

The virus expert said distance is the most important protective measure, especially in indoor-air environments, and everything else, including masks, needs to be layered on after that.

Osterholm chided current CDC director Robert Redfield for recently claiming that all we need is masks to drive Covid-19 into the ground in six weeks.

“I thought it was irresponsible,” Osterholm said of Redfield’s claim.

The infectious disease researcher noted that even in regions where citizens can be fined thousands of dollars for not wearing a mask, such as Hong Kong’s public transportation system, we are still seeing problems with Covid-19. We don’t want people to assume masks will make the difference,” Osterholm said.

Another factor, some field work in places like Philadelphia has shown that roughly one-quarter of everyone wearing face-cloth coverings are wearing them under the nose.

Frieden said there is not a lot of data available on the effectiveness of full face shields, but the bottom line is that people need to be wearing some kind of face covering when they are in any indoor environment. There has been a lot of discussion about the need for updated HVAC systems to provide ventilation never considered necessary before Covid-19, but the former CDC director said becoming infected by touching a doorknob or elevator in a building is more probable than contracting the virus due to an AC system, which was the case with SARS.

“One thing we need to do is know there is no one thing we need to do,” Frieden said. “If anyone tells you they know this virus, don’t trust them,” he added.

Osterholm said anyone who does not know a person who has become infected or died from coronavirus should heed his personal warning about indoor air and large gatherings. He recently warned family members in his hometown of Waukon, Iowa, to not hold a weekend indoor reception for a high school graduate.

“Despite warnings by others, they had it. There was an outbreak that occurred. … On Wednesday, Grandpa died, and on Friday, Grandma died, both previously healthy. That’s what we are talking about,” the world-renowned epidemiologist said.

As businesses and schools attempt to return workers and students, “clever approaches,” such as four days at the workplace followed by 10 days at home in a form of quarantine, need to be tried, Frieden said. But he warned that the models are only as good as the data we have, and that data is not great today. “It is certainly valid to try and see, and the same goes for schools. I’m not saying we should experiment on kids, but we don’t know the right way to do it,” Frieden said.

Some businesses will continue to rely on remote work when possible and delay returns to physical workplaces. Alphabet announced on Monday it is extending its work-from-home order for any workers who do not need to be in the office until next summer. Businesses need to create a feedback loop to evaluate what is working as they try various ideas such as “de-densifying” the workplace. But the former CDC director warned that as Americans return to work and school, there is no such thing as a “work life” or “school life.”

We are all living “Covid lives” now, he said, and that means workers who demand workforce safety measures but then go to a bar with friends at night are invalidating all the efforts during the day to make the workplace safe.

Individuals will need to understand that going back to work means making significant trade-offs in their personal lives, because it is impossible to know where the explosive spread in a community will start, but we do know how disruptive it will be.

“There is no 100% safe other than everyone staying at home, which is too difficult,” Frieden said. “We will be living in a 24/7 Covid world eventually,” he said.