USF professor: Up to 18,000 new Hillsborough Co. COVID-19 cases a day if people ignore social distancing, don't wear masks

Posted at 8:13 PM, Jun 13, 2020
and last updated 2020-06-16 01:10:01-04

TAMPA, Fla. – The Florida Department of Health reports 2,581 new COVID-19 cases overnight. That’s the highest single day of cases reported in Florida so far, and the third day straight of a record-breaking number of cases.

A distinguished professor at USF and an adviser to the Hillsborough County Emergency Policy Group (EPG) warns the uptick in positive cases may only be the beginning of a tsunami of coronavirus cases.

According to the USF professor Dr. Thomas Unnasch, he explains the worst-case scenario could be that we could see up to 18,000 coronavirus cases a day by July 2, just in Hillsborough County.

“The latest predictions, if we continue with, basically, a relaxation of all our social distancing, and people not wearing masks, we can expect to see 18,000 cases a day by July 2 in Hillsborough County alone,” Dr. Unnasch said.

While that scenario isn’t likely to happen, Dr. Unnasch still says if we continue at the rate we’re moving, with people easing up on social distancing, that number is right around 13,000 COVID-19 cases a day.

The best-case scenario, he says, if we ramp up our social distancing practices, that number would be right around 6,000 cases a day in Hillsborough County.

Dr. Unnasch says these numbers were calculated while working with researchers at Notre Dame, and inputting current numbers, in conjunction with current percentages of people wearing masks and social distancing.

He says his projection model is similar to hurricane spaghetti models, and it falls right in line with around a dozen other models done by other researchers.

“Unfortunately, all of them are pointing in the same direction, to different degrees, but they’re all pointing that we’re at the early stages of a new exponential increase,” Dr. Unnasch said.

His projections are an example of 'exponential growth.'

There’s an old brain teaser that illustrates this: You have a pond of a certain size, and upon that pond, a single lilypad. This particular species of lily pad reproduces once a day, so that on day two, you have two lily pads. On day three, you have four, and so on.

Now the teaser. “If it takes the lily pads 48 days to cover the pond completely, how long will it take for the pond to be covered halfway?”

The answer is 47 days. Moreover, at day 40, you’ll hardly know the lily pads are even there.

The silver lining to all of this? Dr. Unnasch says there is a way to stop this. Floridians need to remember to wear a mask when out in public and continue to keep their 6-plus feet of space from others.


He said if more people recognize the seriousness of the pandemic, we can be closer to achieving that best-case scenario.

Dr. Unnasch warns the current numbers are likely a reflection of the amounts of people who have been out protesting, not following social distancing guidelines, and not enough people wearing a mask.

All that in conjunction with the uptick the state already planned for as we began Phases 1 and 2 of reopening the state.

“This virus is clearly an aerosol born – airborne virus – and it’s spread pretty easily by talking loudly or singing or coughing, and you get 50,000 people all crammed together, all chanting together, that’s an ideal situation, unfortunately, for spreading the virus,” Dr. Unnasch said.

Dr. Unnasch says this increase in cases cannot be attributed to additional testing alone. While more test sites are opening up, Dr. Unnasch says the number of tests actually being done in Hillsborough County has been flat or slightly declining.


We want to give you a glimmer of hope here as Dr. Unnasch says we do not need to close the state back up to stop this spread.

He says we can all go about our daily business by keeping our distance and wearing a mask.

The Florida Department of Health (DOH) coronavirus dashboard shows there are more than 73,000 cases, and of those, more than 71,000 are state residents. More than 11,000 people have been hospitalized and more than 2,900 people have died from the virus.

Dr. Unnasch says experts expected the number of cases would go up as the state started reopening, but they didn’t expect numbers to be this high.

“As long as we reached a new equilibrium of like 1,100 to 1,200 cases a day being reported, I wasn’t going to be concerned, but the thing that would concern me is seeing increases day-over-day; 1,100, 1,200, 1,500 and so on. And the last three or four days, unfortunately, that’s exactly what we’re seeing. We’re seeing the start of an exponential increase,” Dr. Unnasch said.


Dr. Unnasch said according to research, it appears that about 50% of people who get the virus don’t spread it to anyone else.

About 20 to 30% of people who get the virus will give it to 1 or 2 other people, and then there is a small group of about 10% of the population who get the virus who are “super spreaders,” essentially people who get the virus and pass it along to dozens of people. But so far, he says there is not a way to identify who those “super spreaders” are.


Dr. Unnasch says a single layer mask made out of a t-shirt will block about 50% of the aerosol particles from coming out. Multi-layered masks, he says block out closer to 75% or 80% of particles.

He says wearing a mask appears to be the single-most effective thing a person can do.

"That did slow things down significantly, but basically caused a lot of other damage. We can beat this on our own if we all take personal responsibility for this, and we don’t have to destroy our economy and don’t have to destroy our lives,” Dr. Unnasch said.

When asked whether temperature checks were helpful when entering a building or business, Dr. Unnasch explained the temperature checks do stop some of the infected people from going inside, but not all.

He said people are the most infectious with COVID-19 about 12 hours before they actually show any symptoms at all.

“Probably 50 to 60% of the transmission that’s going on are from people who are either asymptomatic, never going to show any signs of the infections, or presymptomatic… so you’ll be able to weed out about 40% of people who are symptomatic by taking their temperature, but the other 60% are going to be out there and they’re not even going to know.” Dr. Unnasch said.


Dr. Unnasch said there is a silver lining to all of this, and that is that the death rate is declining.

The age distribution for positive COVID-19 cases is now skewing away from the elderly population, and more toward people aged 19 to 34.

“It seems like the older people and the people who are at risk have gotten the message, and they’re isolating and protecting themselves,” Dr. Unnasch said.

He says while a younger person is less likely to have severe or life-threatening consequences if they get the virus, and that building a herd immunity is a good thing, people in that age range should still be abiding by CDC guidelines, to avoid getting the virus, if possible, when they’re out.

“You hear about these 30-something people who are out there saying ‘my god, this is the sickest I’ve ever been in my life,’ and they’re sick for weeks. I mean, do you really want to be sick for three weeks? Maybe you’re not going to die, but do you really want to be the sickest you’ve ever been in your life for three weeks,” Dr. Unnasch said.