The coronavirus data that will guide when to reopen Florida

The stakes are high as state and local officials puzzle over when to ease coronavirus restrictions: open too quickly and Florida risks a deadly second wave, open too late and the chance of economic recovery gets smothered.

But from the tip of the peninsula to the hills of the panhandle, those trying to grasp the true extent of the coronavirus pandemic are confronted with a series of knowledge gaps, data holes and omissions on the part of the state that make it so that no one has the entire picture of what is really going on.

Each comes with a specific caveat or blind spot, and all the information needs to be taken together to get the best picture of the pandemic.

We flattened the curve. Now it needs to stay that way

When the government and many epidemiologists say we are flattening they curve, they cite statistics that show hospitals staying under capacity and the slowing rates of new deaths and positive cases.

“That doesn’t mean it’s safe to open,” says Thomas Hladish, a researcher at the University of Florida’s Department of Biology and Emerging Pathogens Institute and a consultant to the state health department. “Those don’t go hand in hand. If you said ‘OK, everyone go back to normal life,’ you’d see exponential growth like before because we haven’t built up herd immunity.”

Hladish says there is general agreement among epidemiologists that Florida has flattened its curve, but notes that the flattening is due to the state’s social-distancing measures.

Leslie M. Beitsch, chair of behavioral sciences and social medicine at Florida State University college of medicine, also urges caution. “I think a lot of people want to declare victory right now, but I think that’s very premature.”

Experts also broadly agree that the least painful way of keeping Florida’s pandemic curve flat is expanding the state’s testing capacity so that it can identify, trace and isolate infected people.

“Can we please get more testing? I would urge people to be looking for more testing,” says Dr. William Hanage, associate professor of epidemiology at Harvard T.H. Chan School of Public Health.

Though testing is limited, here’s what we can learn

The number of people with confirmed infections in Florida surpassed 30,500 as of Friday, or about 1 out of every 697 Floridians. That number reflects the total over time, so the majority of these people have likely survived the illness. However, the state does not track recovered people, in part because defining when a person has “recovered” from the illness is difficult, according to the state department of health.

The documented number of infections is not nearly as bad as New York State, where one in every 74 people have been infected by the virus, according to the New York State Department of Health. Nationally, about one person in every 330,000 has been found to be infected.

But Florida, which is third in the country for population, is in the middle of the pack for testing per capita. Florida has completed 300,000 tests since the start of the pandemic, or about 1.3 percent of its population.

Florida has plateaued when it comes to the number of tests reported daily in the past two weeks, averaging about 12,000 people a day. Experts say the rate needs to grow significantly if the state wants to open up safely.

A critical number to watch for is the percentage of positive tests. As a viral outbreak recedes, epidemiologists expect the percentage of tests yielding positive results to grow smaller and smaller.

Florida has been trending downward in recent weeks. The latest figures show about 10 percent of tests statewide are coming back positive, down from a high of 23 percent in March. The rates remain higher in South Florida, at about 15 percent.

“It kind of depends on which people you are testing,” said Dr. Aileen Marty, a professor of infectious diseases at Florida International University. “Initially the positive rate was higher because we were only testing the sickest persons, but as we test others who aren’t sick or symptomatic that rate goes down.”

The ratio of deaths to infections – the case fatality rate – peaked and fell in early March, but has steadily increased in April. About 3.3 percent of people with documented infections in Florida have died, according to the latest counts. But it is not clear if all the dead have been counted.

The state’s total death toll stood at 1,013 as of Friday morning, according to data from the Florida Department of Health.

It is a number that comes with two caveats: The total deaths have conflicted depending on the agency tracking them, with some county medical examiners reporting more deaths than the state health department. And experts say that a recent spike in flu and pneumonia deaths may actually have been caused by coronavirus, reflecting a possible undercount of COVID-19 deaths. The state department of health would not say whether these additional deaths have been included in their published tally of the dead.

Relative to the state’s population, Florida’s death toll has not been nearly as great as many other states.

Hospitals contend with influx of patients

Experts also recommend looking at how many people are showing up at the hospital with symptoms as a way of tracking the pandemic.

“The thing which I personally look at is hospitalization rates,” says Dr. William Hanage, associate professor of epidemiology at Harvard T.H. Chan School of Public Health.

“What you want to see is evidence of a slowing in this because that would be indicative of a slowing in the community in terms of transmission,” Hanage says, noting that he would look to see a two to four week pattern of sustained drops in hospitalizations in an area before social distancing measures might be relaxed.

So far, most of Florida’s counties have been able to stay under 100 percent capacity for hospital beds. You can monitor that in this continuously updated database.

Models show the infection in Florida is slowing, and may have even peaked weeks ago, but their predictions should always be taken with caution.

The pandemic model produced by the Institute of Health Metrics, which has been used to inform decision-making in both the White House and in Tallahassee, says that Florida peaked on April 2, with 77 deaths in one day.

However, its predictions of the peak of Florida’s curve have shifted considerably since it was released, seesawing between early May and early April, possibly as a result of the state’s increased social distancing measures.

The IHME Model assumes that Florida will continue widespread social distancing until early June. But some experts warn that further rounds of social distancing may be necessary until the state is able to detect, trace, and isolate every case of COVID-19.

Kevin Systrom, the founder of Instagram, has created a model that estimates the reproductive number of the virus, or R, by state. R is a number epidemiologists use to measure of how many other people one infected person can infect. Systrom’s estimates, updated daily, show Florida is slightly above the epidemic threshold, meaning that on average, one person is infecting slightly more than one other person across the state.

Systrom’s model uses data from the COVID Tracking Project, which in turn aggregates public data from health authorities. It then uses an algorithm to calculate R. The algorithm is sensitive to big spikes in testing, and assumes that people become infectious with the onset of symptoms, which may skew its results.

Because Systrom is not an epidemiologist or an infectious disease specialist, we ran his model past people who are.

“It’s as good as it gets right now with the data they’re working with,” Marty said.

Epidemiologists track the reproductive number using data on positive tests and day-to-day changes. It can be a signal as to whether an epidemic is growing.

Hladish cited the current social-distancing measures as factors helping the infection numbers stay low.

“If we re-open, that’s going to change,” Hladish said. “If we relax social-distancing, we’re going to go above the epidemic threshold and the epidemic will start growing.”

Keeping an eye out for the next wave:

During the 1918 Influenza Pandemic, the second, winter wave of the disease was greater than the first. Experts warn that expanded testing of both infected individuals and those who have already had the virus will be necessary to stave off such an eventuality once Florida begins to ease social distancing measures.

“Until you do more testing you cant say with any comfort that you’re actually controlling the outbreak, or can control it in its next iteration, the rebound,” says Beitsch. “So you really want to know what you’ve got, both in terms of the infected and the people with antibodies.”

“Moving forward it’s really important to have extensive testing so we can tell if we need to resume social distancing, so high-quality surveillance is really critical,” said Dr. Daniel Weinberger, an associate professor of epidemiology at the Yale School of Public Health.

But until that happens, says Beitsch, it’s best to keep an eye on as many of the secondary numbers and models as possible.