Estimating when cases of the novel coronavirus will peak in Louisiana is not so different from trying to predict the rain — but it’s harder.

“These are like weather forecasts, but we know a lot less about infectious diseases than we know about the weather, and people are always skewering weather forecasts for being inaccurate,” said Samuel Scarpino, a professor at Northeastern University in Boston who models infectious diseases and runs the Emergent Epidemics Lab.

Still, experts are doing their level best. Scarpino is helping to model for the Massachusetts outbreak, and said seeing a peak there within the next three to seven weeks is “certainly in the range” of models, though he said many variables could affect those predictions.

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In New York, which has the highest number of positive coronavirus tests of any state, with 2,382 as of Wednesday afternoon, Gov. Andrew Cuomo said earlier this week that he expects cases to peak within about six weeks.

Gov. John Bel Edwards said Wednesday afternoon that he was receiving “updated modeling from several different sources, and we will be putting those sources side by side so we can come up with the best possible estimate of what we're looking at in terms of the total number of cases.” Louisiana Department of Health officials said Wednesday was "too soon for us to project when we may see a peak in the number of people impacted, but we expect to learn more in the coming weeks, especially as we see an increase in testing."

Louisiana reported 280 known coronavirus cases as of Wednesday afternoon, the fifth-most known cases of any state.

Experts say trying to make such a prediction in Louisiana presents a challenge, when so much is still unknown about the novel coronavirus and any number of factors can change predictions.

”Right now, forecasting isn’t our biggest problem,” said Mac Hyman, a Tulane mathematician who helped model the spread of coronavirus in China. “It’s estimating how many people are actually infected. Before we can forecast, we have to know what the current state is.”

Figuring that out has been frustrated by a lack of testing.

Ochsner Health’s president and CEO Warner Thomas said Tuesday that the hospital system is modeling a number of scenarios using data from other countries, Johns Hopkins University researchers and more. Ochsner is factoring in hospital admissions, ICU admissions, age and other variables.

National estimates show about 15 % of coronavirus patients must be hospitalized. Thomas said Ochsner is finding that to be a good ballpark, but the system is still waiting on too many test results to know for sure.

“This is not a two- to four- or six-week issue,” Warner said. “This is going to go on for a while … we have to think about the new normal over time. It’s more than likely not going to go away.”

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The length of time it can take for coronavirus symptoms to appear makes it especially difficult to forecast the trajectory, according to Susan Hassig, a Tulane epidemiologist. The rising number of people testing positive for coronavirus in Louisiana is still capturing an old snapshot of preexisting infections, she said.

Hassig, who helped model the spread of HIV, noted that dozens of factors that could affect that disease’s transmission: sexual behavior, drug use, contraception, age, how often people switched partners, how advanced the virus had become and more.

Yet still, HIV researchers could lean on “intentional interactions,” as the disease was known to be passed through sex and shared drug needles. With COVID-19, other researchers trying to model it have to account for a virus that’s being passed unknowingly through sometimes-asymptomatic people. Anyone could encounter an infected droplet without realizing it — on a bus, on Frenchmen Street, at Mardi Gras. And people who work in the service industry especially could have a lot of those encounters, she said.

People should assume they can encounter the virus during any visit to public spaces among other people, Hyman said. Going to Rouses should no longer just be grocery shopping as usual: he advised wearing gloves in stores and being careful exchanging money. Before restaurants and bars became takeout only, Hyman said he would wipe down restaurant tables when he went out to eat.

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If enough people embrace them, those sorts of precautions can make big differences in disease modeling, he said. It’s also crucial to prevent people who are infected — even if they don’t know it yet — from spreading the virus.

“If everybody did that tomorrow, we could have an epidemic peak within three weeks,” he said. “But if nobody does it, this will linger until everyone has it. These predictions depend upon how much of the public will change their behavior.”

Tad Dallas, an LSU biology professor who specializes in infectious diseases, said researchers can simulate epidemics using varying assumptions. Models can account for how coronavirus would spread differently as restaurants shut down, people work remotely and practice social distancing.

But still, he said it’s hard to be confident in one specific estimate.

Though it might take time for the data to show it, the social distancing now happening in Louisiana “definitely makes a difference,” Hassig said.

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Rebecca Christofferson, an infectious disease expert at the LSU School of Veterinary Medicine, said that models attempting to predict spread "should account for the impacts of social distancing" guidelines announced in recent days, though others pointed out that Louisiana is likely to see a major spike in positive cases before seeing the benefits of those policies.

One of the major challenges researchers face with the new coronavirus is still not knowing at what point in their illness people who have it are most capable of passing it along to others, meaning new infections are happening at unidentifiable points in space and time, she said.

“The models help us to understand possibilities,” Hassig said. “They cannot predict what is going to happen.”

Staff writers Sam Karlin, Emily Woodruff and Bryn Stole contributed to this report.