How hard will COVID-19 hit Miami-Dade this fall? We explored the potential scenarios

Throughout the course of the novel coronavirus pandemic, public health experts have feared it could follow the pattern set in 1918, when a massive “second wave” of an influenza virus in the fall caused far more deaths and illness than the first, spring wave.

Now, roughly six months after life in Miami-Dade County and much of the world was upended by the COVID-19 virus, concerns over that deadly second wave in South Florida have eased somewhat, according to several public health experts interviewed by the Miami Herald.

Despite guarded optimism about the future, the experts agreed that a severe autumn resurgence could still materialize quickly. Its likelihood, though, may have slightly decreased after an unexpected summer surge that prompted curfews and closures and forced local hospitals to call for out-of-state nursing reinforcements.

While predicting the patterns of a novel virus with any certainty is nearly impossible, the experts generally agreed that Miami’s disastrous late June and July virus spike appears to have reshaped the pandemic landscape for South Florida, prompting more people to comply with physical distancing and masking when around others, as well as generating some level of immunity to the virus in certain, hard-hit pockets of the population.

“I don’t think you’ll see explosive epidemics anymore in the Miami area — that’s over,” said Ira Longini, a disease modeler and biostatistics professor at the University of Florida’s Emerging Pathogens Institute known for constructing sophisticated disease models.

Even with that analysis, what comes this fall in Miami depends on how many control measures, such as curfews and business restrictions, are relaxed, as well as how cautiously people behave in social settings, Longini said. He based his assessment on his model’s projections for Florida, how many people he estimates to have already been infected in the Miami area and how the summer surge changed public perception of the virus’ threat.

That spike on top of the initial spring wave likely generated some level of immunity in about 20% to 30% of Miami-Dade County’s population, Longini said — enough to dampen future outbreaks, but leaving 70% to 80% of people susceptible.

Longini, who has been modeling infectious diseases for decades, cautioned against common misconceptions of so-called “herd immunity,” or when enough people in a population are infected, forming enough immunity to eliminate virus spread in a community. The threshold for such a dynamic to kick in is generally 60% to 70%.

But even if some level of immunity in the population has cut transmission in pockets of South Florida, Longini said, the greater Miami area will likely continue to see flare-ups as the virus circulates in Florida.

“You can’t look at South Florida in isolation,” he said. “ ... If you’ve got one pocket that is still generating cases, it’s feeding others.”

To better understand what Miami’s pandemic autumn might look like, the Miami Herald interviewed infectious disease experts to discuss the different scenarios that might unfold. Though experts could offer little certainty with a still-novel virus, they provided their best educated guesses at what might take shape.

Scenario One: Calm seas

The best-case scenario for Miami-Dade County would be to maintain the status quo, which is within the realm of possibility but not likely, according to public health experts.

That would still mean hundreds of cases per day, and a considerable number of hospitalized patients for the foreseeable future, until a vaccine arrives.

All the experts interviewed by the Herald, however, predicted some level of rise in the coming weeks.

Eric Toner, a senior scholar at the Johns Hopkins Center for Health Security, said the only scenario he’s sure of is what won’t happen: The virus won’t disappear.

“It’s not going away,” Toner said. “What success looks like is pretty much where you are right now, which is, a modest level of disease.”

Under the best-case scenario, businesses would continue to operate with restrictions and people would be asked to maintain physical distance and wear face masks around others. As soon as people start to give up on those behaviors, Toner said, another spike is sure to follow.

“You can’t predict if it would be as fast of a spike or as high of a spike, but you could see a significant spike that could lead to shutting things down again,” Toner said.

Scenario Two: A rising tide

Most public health experts interviewed by the Herald agreed that a rise in cases is likely coming, due to colleges and universities reopening as well as more business restrictions being lifted after the summer surge.

Longini, the University of Florida modeler, said he anticipated that increase to come in the next one to two weeks, but was hopeful that it would be a gentler incline than June and July’s spike.

“You won’t get this quick, exponential rise,” Longini said, of Miami’s most likely outlook. “You’d probably get a slower rise.”

Toner, of Johns Hopkins, agreed with the one- to two-week timeline for an increase in new cases in the Miami area.

Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health, said it was “really unlikely” an area as hard-hit as Miami would experience another exponential surge, as long as Florida kept its recently improved testing system in place and made sure to make those tests available to everyone.

Spiking cases and hospitalizations earlier this summer spurred increased “situational awareness” in Miami, Hanage said.

“If you have a situation in which you’re able to see that cases are increasing, then people I think will have a natural reaction to that,” Hanage said. “They’re going to start doing things themselves to limit transmission.”

A gradual incoming tide of increasing COVID cases would give Miami-Dade’s government the chance to show it can manage an expanding outbreak in a way it was unable to do when cases soared from June into July and hospital admissions from the coronavirus topped 2,000.

This time, with current COVID patient volume in county hospitals below 500, Miami-Dade Mayor Carlos Gimenez says the county has programs and assets to tamp down cases that weren’t in place in June.

One is a system to offer free hotel rooms to isolate people who don’t want to go home, either because they have COVID or think they were exposed to it. While the early days of the program relied on hospitals to pair people with county-supplied hotel rooms, Miami-Dade is now advertising availability to the general public and secured an additional 400 rooms from Florida. On Tuesday, Miami-Dade reported 382 of the program’s roughly 500 rooms were occupied.

If COVID cases begin a steady climb again, the scenario would give Florida’s network of contact tracers the chance to prove itself in Miami-Dade. Ahead of lifting most business restrictions in May, Gimenez said he planned to spend county dollars hiring 1,000 contact tracers to quickly track interactions with people who caught COVID, a proven public health method of cutting transmission. He couldn’t get the administration of Gov. Ron DeSantis to agree to pay for that many, but the state in June agreed to accept $14 million from Miami-Dade to bolster a tracer workforce that the Gimenez administration said now has about 350 people on it.

“We have a much more robust tracing system,” Gimenez said at a Miami news conference with DeSantis on Friday, when the two discussed lifting restrictions and allowing schools to reopen in the coming weeks. “We also have more people that are actually doing contact tracing. Now that we have the positivity rate down, it’s really incumbent upon the Department of Health that when we do get positives, that we do really robust contact tracing.”

Miami-Dade’s rate of positive COVID tests for new cases in Florida residents has kept below 5% for much of the week and is averaging just above that over the last two weeks.

Florida’s Department of Health has so far refused to provide the Miami Herald with the latest county report on tracer results, and local mayors have complained about a state effort that’s not matching the need in Florida’s hardest-hit county.

At a special COVID meeting of the Miami-Dade County Commission Tuesday, Commissioner Dennis Moss said he wanted a bigger public education effort on the importance of contact tracing to encourage participation heading into the fall. “On the issue of contact tracing, one of the biggest problems we’re going to have in that area is developing trust. I believe there’s a sense contact tracing won’t be used for the good intended purpose it’s there for. ... That’s something we have to really work on.”

Masks could be a factor in Miami-Dade’s favor this fall. While the county had some mask rules in place in May, Gimenez didn’t order a countywide mask mandate until July and police and code inspectors began issuing fines for violations then as well. Enforcement continues, with 96 citations reported on Sept. 10 alone.

In a letter to DeSantis and state Surgeon General Scott Rivkees this week, Miami Beach Mayor Dan Gelber called out Florida for failing to issue a statewide mask mandate, leaving local municipalities to fight an uphill battle on enforcement.

He also highlighted the failures of the state-run contact tracing program.

“In September your contact tracing program was only able to reach a little over one-third of those infected in Miami-Dade,” Gelber wrote in the letter. “Some of the problem relates to people not wanting to cooperate. But other places have been able to do markedly better.”

Scenario Three: Another surge

A far worse scenario — another wave of cases that overwhelmed hospitals — would likely start off looking just like the rising tide scenario.

Though public health experts are cautiously optimistic Miami can keep its case level down, another devastating surge is a realistic possibility, they said, especially if behaviors revert to where they were in May.

“If this pandemic has taught us anything, it’s to be humble,” said Mary Jo Trepka, an epidemiologist and public health expert at Florida International University. “We think we know what’s happening based on the past, and then the past fools us.”

Trepka said that Miami was able to curtail its last surge without a complete lockdown, but there are still several hundred cases per day in the county.

“That’s what we had back in May, when we reopened,” she said. “So the possibility of there being another resurgence is definitely there. ... Will we do better this time?”

It’s still quite possible, Trepka said, that Miami-Dade could seem to gradually put COVID behind it as hospital figures plateau or taper off, and then spike as COVID spreads rapidly across the county again later in the fall.

Gimenez has described that kind of an event in recounting telephone briefings with Dr. Anthony Fauci, the head of the National Institute of Allergy and Infectious Diseases and one of the Trump administration’s top voices on COVID.

“Some of the information we’re getting from the White House and our medical experts is that there is an expected second surge in the fall,” Gimenez told reporters last month. “The lower we can get our numbers right now, the lower that second surge will be.”

One potential x-factor: flu season.

Public health experts are split on whether communities in the U.S. should be bracing for a “twindemic,” or a combined flu and COVID surge in the fall.

Longini, of the University of Florida, who has been studying influenza for decades, predicted that the flu season would be mild to non-existent this winter due to physical distancing and masks from COVID mitigation as well as “viral interference,” when different respiratory viruses compete with each other for hosts.

“We’ve seen this with the flu many times,” Longini said, citing the 2009 H1N1 pandemic as a recent example. “... With the flu season in the Southern Hemisphere, COVID came in and out-competed seasonal flu, as well as all the social distancing. There was no real flu in the Southern Hemisphere this year.”

Despite a number of factors aiding Miami in suppressing another surge this fall, public health experts all expressed some degree of concern over unsafe behaviors that could prompt another surge regardless.

Toner, of Johns Hopkins, said he’s disturbed by seeing examples of people not adhering to public health guidance and said that the rejection of such measures has led to untold illnesses and deaths.

In Miami, Trepka said there’s a longstanding tradition of people not complying with public safety measures. She cited one example everyone can relate to: traffic.

“[Refusal to wear masks and distance] is not so surprising when you think about how people follow our traffic rules,” Trepka said. “We don’t have a very good track record on compliance.”