‘Burning through the population’: Delta fuels Florida’s worst COVID wave
In a matter of weeks, the highly contagious delta variant of the virus that causes COVID-19 has fueled the worst spike in new infections since the pandemic began in March 2020, according to an el Nuevo Herald analysis of state-level data.
Florida’s COVID-related hospitalizations have broken daily records for 11 days in a row, according to data published daily by the United States Department of Health and Human Services, with many hospital administrators moving to cancel elective procedures in order to save space and ensure staff and resources are available to care for the flood of new patients. The state has also shattered single-day records for new cases five times in past two weeks, including Tuesday when the state added 24,753 new cases, according to data published by the CDC Wednesday.
Unlike the past surges of COVID-19 cases, where the elderly made up the majority of severe cases, this new wave is increasingly affecting younger populations as well. In terms of the number of children hospitalized with COVID-19, Florida has ranked among the two worst states in the nation and hospitals have been sounding alarms.
“This delta variant is burning through the population,” said Jason Salemi, an epidemiologist at the University of South Florida who has tracked the state’s COVID data since the beginning of the pandemic. “It’s infecting a lot of people very, very rapidly.”
Salemi also attributes this dramatic increase in cases to high numbers of individuals in Florida not being protected through vaccination (around eight million who are eligible), relaxation of measures that lower the likelihood of transmissibility, the summer heat driving people indoors and tourists.
New cases increased almost eightfold during the month of July and have more than doubled in the past three weeks, according to a Herald analysis using seven-day rolling averages of daily Florida Department of Health (DOH) case data published by the Centers for Disease Control and Prevention.
‘There’s a lot of unknown’
The CDC tracks more than 18 lineages of SARS-CoV-2 in the United States, with the delta variant making up more than 85% of samples the agency sequenced during the last two weeks of July. Variants may carry mutations that make a virus more contagious or cause more severe symptoms or that evade the effectiveness of therapies and vaccines.
Data collected over a four-week period and published by the CDC suggest that through July 17, out of almost 4,000 positive tests collected in Florida sequenced, 65% were delta. Sequencing refers to studying a virus as it changes.
Recent studies also suggest that the delta variant is now the leading cause of infections in Miami-Dade County, making up more than 90% of infections among patients hospitalized at Jackson Health System and the University of Miami Health System, according to UM researchers and doctors tracking mutations of SARS-CoV-2, the virus that causes COVID-19.
Dr. David Andrews, a pathologist and UM professor leading the effort to sequence the virus in Miami-Dade, said the rapid takeover of the delta variant as the predominant strain circulating in South Florida is a hallmark of its increased contagiousness.
Andrews said scientists with the CDC and other health agencies around the world have been trying to measure just how contagious the delta variant of SARS-CoV-2 is, with some comparing the ease of spread to chicken pox.
DOH has never published information on variants, but under threat of a lawsuit from the Herald and a consortium of other news organizations, DOH now shares data on variants once a month.
That data, Salemi says, is problematic because it doesn’t provide enough context to understand how prevalent any one strain is at any given time, since the data do not state when the samples were sequenced or how many of them went through the sequencing process.
What is clear from CDC data is that delta is the dominant COVID strain in Florida and across the United States.
“The degree of contagiousness and rate of transmission for the delta variant is completely off the charts compared to all the previous variants,” Andrews said. “It is absolutely unprecedented.”
Mary Jo Trepka, an epidemiologist and professor at Florida International University, says that while the high case counts of the current wave are comparable to the surge in January, that prior wave was driven primarily by a rise in test volumes from people preparing for the holidays.
But last month saw a 670% increase in Florida’s seven-day rolling average of new cases from July 1 until the 31st, according to DOH data published by the CDC and analyzed by the Herald. During that same time, tests performed, as reported by the CDC, saw only a 118% increase in its seven-day rolling average, indicating the increase in new cases cannot be explained by an uptick in testing alone.
Fueled by a much more contagious variant of the virus, this new wave has caused a much steeper increase in new cases and hospitalizations than in the past.
“People tend to be getting sicker, or at least becoming infectious slightly more quickly and then when they do become infectious, they’re much more infectious because they’re harboring so much more virus,” said Salemi. This is making the surge of hospitalizations track closely behind the surge of new cases, according to Salemi.
“There’s a lot of unknown,” Trepka said of surging hospitalizations and the rapid spread of the virus, which have not shown signs of slowing down.
“I don’t think that hospitals have seen their peak yet. That is a major problem. That is what we really have to be paying attention to. It’s going to be really rough,” she said.
Trepka said she is especially concerned with how widespread the surge is in Florida, which differs from previous waves that saw hot spots flare in the southeastern part of the state. Now hospitals are raising alarms in Jacksonville and Orlando in addition to South Florida.
“It’s not like we can ship people from Miami to a neighboring county because the whole state is affected,” said Trepka, citing last Tuesday’s community profile report from the White House, which shows that 12 Florida counties, including Miami-Dade, are among the top 25 in the country in terms of highest percentage of COVID-19 cases reported.
Counties with large populations like Miami-Dade and Broward are expected to be in the top range, said Trepka. But in Tuesday’s report, even Polk County, where the population is roughly one-fourth the size of Miami-Dade’s, ranked in the top 15.
“Now it is everywhere... and I think the reason is low vaccination rates in many counties in Florida,” she said.
A much more contagious version of the virus also means that it will take communities longer to reach the threshold of so-called herd immunity, where the percentage of people immunized by vaccine or prior infection is so high that the virus can no longer find an abundance of hosts and the disease stops spreading.
“I am concerned that now with this much more infectious variant out there proliferating in the unvaccinated population, it’s going to raise the bar for the degree of herd immunity required for us to get past this pandemic,” said Andrews, the UM pathologist.
While the Infectious Disease Society of America had estimated a threshold of 60% to 70% for herd immunity for the original strain of the virus, the organization said this week that the spread of the delta variant had pushed that threshold up to 80% to 90%.
Less data: ‘Flying blind’
The CDC publishes daily case counts for the entire state, but since DOH stopped daily reporting, the state agency is no longer providing that critical data to the public or to local leaders.
Recently some have publicly urged Gov. Ron DeSantis and the Department of Health to resume the daily reports.
“We would wish for more frequent reporting from the state so that we can do a better job of being on top of daily numbers,” said Miami-Dade County Mayor Daniella Levine Cava during a press conference with university presidents on Wednesday.
Recently, the county mayor called on Miami-Dade hospitals to begin reporting data on the number of patients hospitalized with COVID, in ICUs, on respirators and other key metrics.
The county began publishing that data online last week, and Levine Cava said it will inform key decisions by her administration in the near future. On Aug. 5, Levine Cava announced a new policy requiring weekly COVID testing of all Miami-Dade employees who aren’t vaccinated. The county government has a workforce of about 29,000.
“We have a lot of new factors and we’re all doing the best we can to protect people,” she said.
While being interviewed by CNN’s Chris Cuomo last week, Miami Beach Mayor Dan Gelber said mayors were “flying blind in the midst of this huge surge.”
What comes next?
Although he said it is important to get everyone vaccinated, Salemi added a massive campaign effort would come too late, and that implementing mitigation efforts in order to flatten the curve now would be more effective.
“Even if three million people were to get vaccinated tomorrow, if they’re getting Moderna or Pfizer, it’s five to six weeks before they’re protected,” he said. “It’s not going to solve what’s happening now.”
Individuals cutting down on meeting in big groups and avoiding going to crowded places in the next month would be a big help, according to Trepka.
As for how long this wave will last, Salemi says that’s probably a few more weeks.
“I just assume that there will come a point, whether it’s the third or fourth week in August, that we will hit a peak because there are just so many people that will have either vaccine-acquired immunity or infection- acquired immunity, and those people are going to start building up some immunity to the delta variant.”
He said that, unless an escape variant emerges — something that is very good at evading the vaccine — this should be the last wave Florida experiences.
“At some point the numbers just won’t be able to keep going up. There can’t be enough people in the population, and then they will start coming down.”
Miami Herald investigative reporter Sarah Blaskey contributed to this report.
This story was originally published August 11, 2021 at 8:00 AM.
