On May 4, the day Shelby County began Phase I of “Back to Business,” the health department reported 23 new cases of COVID-19.
That was the lowest daily increase since Mayor Jim Strickland issued his “Safer at Home” on March 23.
The next day, however, there were 109 new cases, the fifth-highest increase since Shelby County recorded its first COVID-19 case on March 8.
The next day there were 56 new cases, then 92.
The uneven ebb and flow of daily numbers can obscure the slowly rising tide of local confirmed COVID-19 cases and related deaths.
Even more confusing, daily numbers reported since May 4 have almost no bearing on how reopening the economy has impacted the spread of the coronavirus.
“First, with an incubation period of up to 14 days, cases reported through this week likely reflect infections transmitted up to two weeks ago,” Vanderbilt University researchers reported Wednesday, May 13.
“Second, because of this time lag, we believe it is too early to assess the impact of businesses reopening across the state or of more Tennesseans resuming activities outside their homes.”
How early? The Vanderbilt researchers didn’t say. But given the 14-day time delay, local officials aren’t entirely sure when to start the clock for determining whether and when to start Phase 2.
“We’ll be discussing that and looking at all of the numbers,” said Dr. Manoj Jain, the infectious disease expert advising the local COVID-19 task force.
The time delay factor is just one of the complications facing local officials as they try to decide whether to re-open the economy further, or tighten it up once again.
Both the Shelby County Health Department and the joint task force’s “Back to Business” framework have established data-driven criteria for moving to Phase 2.
The health department’s directives refer to them as threshold criteria and there are four:
- Stability or reduction in new cases over the most recent 14-day period.
- 85% or less of total ICU bed capacity.
- Suitable capacity for the public health system to conduct surveillance, contact investigations, monitoring, outbreak management, and enforcement.
- Availability of testing resources, capacity, and rapid data sharing results.
The “Back to Business” plan calls them indicators or conditions. They cover the same four categories but in much more detail.
For example, that plan requires that the public health system receive lab results in less than 48 hours, assign cases to contact tracers in less than 24 hours, and complete those investigations within 48 hours.
That last requirement seems the most daunting at this point. As of Tuesday, the health department had not completed more than 700 (20 percent) of its contact investigations.
But as Wednesday’s Vanderbilt report made clear, when it comes to controlling the spread of the novel coronavirus, there is no magic number.
“Tennessee faces an evolving epidemic as Tennesseans begin to engage in more economic activity outside their homes, and as testing capacity continues to expand,” the researchers concluded.
Some local numbers are encouraging, others are troubling, and all can be a bit confusing.
The percent of people who test positive for COVID-19 is declining and has fallen below eight percent — a possible sign that a sufficient number of people are being tested to find those who are infected. Then again, the declining “positivity rate” might just be an indication that too many infections are going undetected.
The number of people who visit local emergency rooms with influenza-like illness (ILI) rose from 2 percent to 7 percent over the weekend — a possible indication that cases might be on the rise since the county went “Back to Business” on May 4. Those who are infected generally start noticing flu-like symptoms within 3 to 4 days. Then again, the ILI numbers were back to normal this week.
The number of COVID-19 related hospitalizations here since May 5 nearly tripled (99 total) from the number the week before (35 total), according to the state department of health. Then again, the numbers have fluctuated dramatically, from a high of 44 hospitalizations on May 6 to a low of 1 on May 10. And only about 70 percent of local ICU beds are being used, a number that has remained steady and falls well below the 85 percent capacity that will trigger concern.
The rate of transmission of the virus, is hovering just above 1 locally and statewide, and has been for several weeks. That’s good because it shows the lethal spread of the virus has slowed dramatically since mid-March when transmission rates were above 3. But that’s also bad because the number of people who are infected, hospitalized and die will continue to increase until the rate of transmission goes below 1 and stays there.
The rate of transmission of the virus (often called the R-naught), the average number of people who are infected by someone with the virus, is hovering just above 1 locally and statewide, and has been for several weeks. That’s good because it shows the lethal spread of the virus has slowed dramatically since mid-March when transmission rates were above 3. But that’s also bad because the number of people who are infected, hospitalized and die will continue to increase until the rate of transmission goes below 1 and stays there.
All of those numbers could merely be a reflection of recent increases in testing locally and across the state, the Vanderbilt study suggests, or they could become more concerning.
“Recent changes in testing capacity in Tennessee makes modeling COVID-19 trends difficult because the rise in the number of cases could either reflect improved detection of existing infections as testing capacity increases, evidence of an increase in transmission, or both,” the researchers said.
NEW CASES AND TRACES
The rush of daily COVID-19 news is filled with data.
There are daily numbers and cumulative numbers, raw numbers and rolling numbers, positivity rates and R-naughts and trajectories.
“I like the numbers. That’s why I got into public health in the first place, but it can get kind of numbing after awhile,” said Becky Kronenberg, a first-year graduate student in the UofM’s School of Public Health. ”There are so many numbers and so many different ways of analyzing them, even I’m starting to tune them out. But I try to keep in mind that behind all the numbers are real people.”
Last week, Kronenberg saw the most important numbers up close and personal.
She sat in a large room at the health department with other volunteer contact tracers — nurses, doctors, police officers, and medical or grad students.
She had a desk, a phone, a set of instruction, and a pile of folders containing newly identified cases of COVID-19.
“I made the early calls to the people who had just tested positive and need to be quarantined,” Kronenberg said. “A nurse behind me was making the later calls to people we’d been monitoring for several days. You get a lot of voicemails.”
Kronenberg is among a growing number of local contact tracers.
Their job is to call each person who tests positive for COVID-19, and their close contacts who might have been exposed, and persuade them all to stay home for 14 days until they are no longer infectious.
“Most people are very cooperative and gracious about it,” Kronenberg said. “Some are not, but you do what you can to explain how important it is to break the chain of transmission.”
As of Tuesday, local tracers have contacted 3,421 people who tested positive and identified 5,866 contacts. Of those, 1,875 are currently in quarantine.
Still, about 700 positive cases have not been completed, and the caseload is growing every day.
The number of confirmed new cases of COVID-19 are widely reported and watched.
New cases provide a daily snapshot of how quickly the disease is spreading through the county. They also let public health officials know of the challenges ahead — for contact tracing, isolation and quarantine, and for hospital use.
But the new daily case numbers have fluctuated wildly from 1 to 210. When they dig into the numbers, health officials can explain the daily rise and fall.
- Changes and overall increases in the number of people who get tested.
- Delays in lab results that cause new positives to be reported in varying batches.
- Specific outbreaks at places like the jail or a long-term care facility that cause new case numbers to spike.
That’s why local officials are paying more attention to the trajectory of new cases over time.
BtoB wants to see “flat or negative growth rate in new cases in the most recent 14-day period.” It doesn’t define “flat”.
SCHD wants to see “stability or reduction in new cases over the most recent 14-day period. It doesn’t define “stability.”
In the 14 days before Phase I began May 4, there were 1,081 new cases reported, or about 77 a day.
In the 14 days before that, there were 997 new cases reported, or about 71 a day.
That’s an 8.5 percent increase, which qualified as “flat” and “stable” enough for launch Phase 1.
From May 5-12, there were 618 new cases reported, or about 77 a day.
If that number holds steady through early next week, officials will be more inclined to launch Phase 2.
ICU BEDS AND PATIENTS
On May 4, the opening day of “Back to Business”, the county reported no new hospitalizations.
Two days later, on May 6, it reported 44 new hospitalizations, according to the state health department.
The next day 27 more, the day after that 16 more.
The number of COVID-19 related hospitalizations here since May 5 nearly tripled (99 total) from the number the week before (35 total), according to the state Department of Health.
The sudden and rapid increase had nothing to do with the May 4 “Back to Business” plan.
That’s because it generally takes 14 days for someone who is infected with coronavirus to develop symptoms, get tested, and end up in the hospital.
That 14-day delay won’t show up until next Monday, May 18.
But the number of people who are hospitalized can be confusing for another reason.
As many as many as 75 percent of COVID-19-related hospitalizations are considered PUI — persons under investigation. They’re awaiting test results.
That uncertainty is one reason officials are paying more attention to ICU bed capacity.
Those numbers are more telling and encouraging.
Shelby County hospitals have about 500 ICU beds available. That includes the 30 ICU beds at the emergency field hospital opening this week at the old Commercial Appeal building on Union.
In recent weeks, the number of ICU beds in use has held steady at about 350 — about 75 percent of capacity. Both the BtoB nor the SCHD want that number to stay below 85 percent.
If current numbers hold through early next week, officials will be more inclined to move to Phase 2.
But officials are concerned about the growing number of COVID-19 cases in adjoining counties. Tipton County, for example, reported a massive spike of 214 cases last Sunday.
About 25 percent of the COVID-19 patients in local hospitals are from other counties.
As Kronenberg learned last week, all of those numbers represent real people whose lives are being disrupted and in some cases destroyed.
So far, COVID-19 has killed at least 77 people in Shelby County. That’s a death rate of about 8 per 100,000.
That’s a relatively low death rate compared to homicide (14.6), flu/pneumonia (19), drug overdose (21), and firearms (24.7).
But it’s double the COVID-19 death rate in Davidson County (4), which has recorded 300 more cases.
And those 77 people died over the course of about two months. If that rate continues over the next 10 months, the virus will have claimed more than 460 local lives in a year.
Only heart disease, cancer, stroke and unintentional injuries claim more local lives each year.
“I commend the health department and everyone who is trying to tackle this problem,” Kronenberg said. “It’s difficult enough when you look at the numbers. But it’s even more daunting when you talk to the real people involved.”
Last week, she spoke to a younger woman who had gotten back her sense of smell and taste and was feeling better that day.
“The next day was her birthday and she wanted to know if she should celebrate,” Kronenberg said.
She also spoke to an older man who had tested positive along with his wife, sister, mother and father.
“They all lived in the same house and his father had just died the day before,” Kronenberg said. “And he said his wife’s temperature had gone up and her chest was hurting and he wanted to know what he should do.”
This story first appeared at dailymemphian.com under an exclusive use agreement with The Institute. Photos reprinted with permission of The Daily Memphian.