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Doctors assess COVID-19 ‘breakthrough’ cases in Miami

Three physicians from the Miller School of Medicine joined Centers for Disease Control and Prevention administrators to talk about these rare instances, effective treatments, and the virus variants that may be prompting them.
Natalia Dubom, of Honduras, gets the Johnson & Johnson COVID-19 vaccine at Miami International Airport, Friday, May 28, 2021, in Miami. The vaccine was offered to all passengers arriving at the airport. Florida's Emergency Management Agency is running the program through Sunday.  (AP Photo/Marta Lavandier)
Natalia Dubom, of Honduras, gets the Johnson & Johnson COVID-19 vaccine at Miami International Airport on Friday, May 28, during an airport vaccination drive organized by Florida's Emergency Management Agency. Photo: The Associated Press

Although it is extremely rare, some people who have been vaccinated against COVID-19 are still able to contract the virus in what is called a “breakthrough” case. And at the University of Miami Miller School of Medicine, physicians are paying close attention to this small subset of patients and are trying to understand how and why some people are more susceptible to the disease.

To share their findings, three physicians at the Miller School of Medicine joined two doctors from the U.S. Centers for Disease Control and Prevention (CDC) recently to talk about these breakthrough cases and the best ways to treat them. Dr. Lilian Abbo, a professor in the Miller School’s Division of Infectious Diseases; Dr. Shweta Anjan, assistant professor in the Division of Infectious Diseases; and Dr. David Andrews, associate professor in the Department of Pathology and Laboratory Medicine, spoke to more than 600 infectious disease physicians last week as part of a weekly video conference hosted by the CDC and the Infectious Disease Society of America.

Dr. Emily Koumans, the CDC’s Clinical Disease and Health Systems team lead for the COVID-19 response, detailed the national picture on breakthrough cases. Koumans said that since April, more than 10,000 vaccinated United States residents have contracted COVID-19. Of those individuals, 63 percent were female and the median age was 58. In addition, she said 27 percent of these patients were asymptomatic, 10 percent were hospitalized, and 2 percent died. Although the CDC was only able to sequence test results from a little more than 5 percent of these breakthrough cases, of those 555 patients, 56 percent had the UK variant, and the majority had a COVID-19 variant of concern, such as the South African, Brazilian, or California variants.

Currently, across the United States about 42 percent of the population is fully vaccinated against COVID-19, according to the CDC. In Miami-Dade County, that number is 46.8 percent, and in Broward County 41.8 percent of residents are fully vaccinated. University of Miami physicians hope that in future weeks, more South Florida residents will get vaccinated. According to Abbo, this will help prevent the growth of COVID-19 variants and more breakthrough cases.

Dr. Lillian Abbo
Dr. Lillian Abbo

“We need to remain vigilant with the emergence of new variants and cases coming from South America,” said Abbo, who is also chief of Infection Prevention and Microbial Stewardship at Jackson Health System. “And we must continue to protect ourselves and those around us by continuing to wear masks around unvaccinated individuals and vulnerable patients until the pandemic is globally under control.”

In her presentation, Abbo outlined the breakthrough infections she has seen in a small number of patients and hospital employees. While they are typically not fatal cases, Abbo still wants to investigate why the COVID-19 vaccines have not provided protection for these people.

“Clinicians need to be aware that breakthrough infections are a possibility, and we are trying to understand . . ,why are we seeing this lack of clinical response in [some] patients,” she said. “We do know that the vaccine protects against mortality, but this is something that we are seeing a little more frequently than three months ago.”

Dr. Shweta Anjan
Dr. Shweta Anjan

Anjan went on to describe the breakthrough cases that they have seen among 27 patients in Miami. She said the majority of these patients were immunocompromised and recently had an organ transplant, and they often had other health conditions, like hypertension or diabetes. In addition, most breakthrough patients were Hispanic and between the ages of 58 and 89 years old. Also, half of the patients mentioned they had been exposed to an unvaccinated family member with COVID-19, Anjan said. Once diagnosed with COVID-19, most of the 27 patients received monoclonal antibody treatment, along with high-dose intravenous steroids, and went home.   

However, since researchers believe that variants of COVID-19 may be prompting these breakthrough cases, Andrews—who is leading a University effort to track variants of COVID-19—also presented during the video conference.

Andrews convened a research team in January to develop tests for common COVID-19 variants—such as the UK variant—and to sequence some of the positive test samples to learn what variants are circulating in the University’s student and patient population. Since Andrews is also the vice chief of pathology for Jackson Health System, he was also able to include samples from patients in their three hospitals, offering a more comprehensive snapshot of COVID-19 across Miami-Dade County.  

Dr. David Andrews
Dr. David Andrews

At the start of their sampling, Andrews said the team noticed a sharp increase in the UK variant. But it quickly began to see many other variants emerge, including strains from Saudi Arabia, Aruba, Nigeria, and other diverse geographic origins—along with the California, New York, and Brazilian variants. This was not surprising because of Miami’s diverse population and its reputation as a gateway to the Americas.

“Today, although [the UK variant] still remains a significant percentage and the predominant variant, with roughly 40 percent of samples, we have seen an emergence of other variants. And about 80 to 90 percent of our samples are a variant of concern or variant of interest,” he said.

In their last sequencing, Andrews noted that 27 percent of his samples contained the Brazilian  variant, 18 percent had the New York variant, and 8 percent of samples represented the California variant, along with two samples that contain an emerging variant of interest from Colombia.

Fortunately, however, Andrews said that the decline in positive COVID-19 samples points to the effectiveness of the vaccines. “The good news is that because cases are falling—despite significant variant expansion—this likely indicates the vaccines in use are protective against the prevailing circulating variants,” he pointed out.