(CNN)When Shaila Rivera and her new husband returned home from their honeymoon and tested positive for Covid-19, they expected a phone call from their local health authorities in Florida asking for a list of people they'd been near so that contact tracing could begin.
The Riveras waited for that phone call. And waited. And waited. But the call never came.
"I was shocked," said Rivera, a nurse who has since recovered from her bout with the virus.
Despite claims that Florida traces every case of Covid-19, a CNN investigation found that health authorities in Florida, now the nation's No. 1 hotspot for the virus, often fail to do contact tracing, long considered a key tool in containing an outbreak.
Florida set a record for most coronavirus cases in the US in a single day on Saturday, with a total of 11,458, according to data compiled by Johns Hopkins University, and on Sunday, the state surpassed 200,000 Covid-19 cases.
Florida's contact tracing challenges are indicative of how hard it is for states hard hit by Covid-19 to do proper contact tracing, which is a challenge even under the best of circumstances. The virus is so far along in states like Florida that it's a seemingly Herculean task to track down every infected person and follow up with all their close contacts.
CNN spoke with 27 Floridians, or their family members, who'd tested positive for Covid-19. Of those, only five said they had received a call from health authorities asking for their contacts.
There are concerns about contact tracing nationally, not just in Florida. In an interview in June, CNN asked Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, how he thought contact tracing was going in the United States.
"I don't think we're doing very well," he answered.
What is contact tracing?
Contact tracing is a centuries-old practice, and the basics haven't changed much: Essentially, health care workers ask infected people for a list of everyone they've been in contact with while potentially contagious. The worker then tells those contacts to quarantine themselves and watch for symptoms.
A spokesperson for the Florida Department of Health in Miami-Dade County sent CNN a statement about contact tracing in her state.
"When the Department of Health receives notification that a person has tested positive for COVID-19, the department conducts an extensive epidemiological investigation in conjunction with the [Centers for Disease Control and Prevention] to identify individuals who may have had close contact with the virus. Those individuals are then notified by their county health department and instructed to self-isolate for 14 days after their exposure to the virus, and to contact their county health department and health care provider immediately if they develop symptoms. This process is followed for all individuals who test positive in Florida," Olga Connor wrote in the email.
Number of contact tracers in Florida unclear
It's unclear how many contact tracers are employed by the state of Florida, as spokespersons for the Department of Health gave CNN two different numbers.
"More than 1,600 individuals, including students, epidemiologists and other staff from across the Department, are currently involved in contact tracing every positive case of COVID-19 in Florida," Candy Sims, a spokesperson for the Florida Department of Health in Broward County wrote to CNN.
The department has engaged a private company to hire an additional 400 contact tracers, Sims added.
But Alberto Moscoso, a department of health spokesperson, cited a larger number, writing to CNN that Florida has 2,300 "individuals involved in contact tracing."
Sims and Moscoso did not respond to CNN inquiries about the differences in their numbers.
"Immediately notify people you have had close contact with while ill," according to the graphic, noting that those contacts should then quarantine for 14 days.
The Florida infographic doesn't explain what to do if someone tests positive for Covid-19 but has never shown symptoms. According to the CDC, in that case, people should be notified if they had close contact with the infected person two days before that person took the Covid test.
5 out of 27 Floridians received contact tracing
Of the 27 Floridians who've tested positive for Covid-19, five told CNN said they had received a call from a health official asking for their contacts.
Among the 27 cases, the earliest diagnosis was in February, and the most recent was last week.
The Riveras contracted Covid in early March, when contact tracers were under considerably less pressure than they are now. Shaila Rivera said an official from the Miami-Dade County Department of Health called and asked questions about their illnesses but didn't ask about their contacts.
"We were surprised," said Rivera, a pediatric nurse practitioner. "The whole conversation was less than a minute. There were no questions like who did you have contact with? Did you go to work? None of that."
Eleven other people out of the 27 said they, like the Riveras, received calls from a Florida health official but were not asked for their contacts.
David Pugh, who lives in Broward County, said he received such a call.
"I don't know that we can count on the state to do a thorough job. I think there are obviously flaws in the system," he said.
Doubts about the usefulness of contact tracing
Contact tracing has been done since the very first case in the United States more than five months ago, and there are several reasons why it has failed to contain the outbreak.
"How do you do contact tracing when someone doesn't have any symptoms?" Fauci said in his interview with CNN. "The standard, classic paradigm of identification, isolation, contact tracing doesn't work no matter how good you are because you don't know who you're tracing."
Also, he said some people are hesitant to talk to government officials.
"The dots are not connected because a lot of it is done by phone," Fauci said. "Fifty percent of the people because you're coming from an authority, don't even want to talk to you."
On top of these problems, some experts doubt the utility of contact tracing in areas like Florida where cases are spiking.
Epidemiologist Michael Osterholm urged Florida leaders to focus on other strategies, such as figuring out where the virus is spreading.
With thousands of new cases a day in Florida, Osterholm doubted that contact tracing would have much of an effect.
"If Florida could get back under 50 to 100 cases a day, contact tracing could be helpful. But right now, it's not likely to have any measurable impact," he said. "It's like trying to put out a forest fire with a single fire truck. It just won't make a dent."