Why we’re seeing more breakthrough infections and what it means

With more than 161 million people now fully vaccinated in the United States, experts say we are bound to see reports of groundbreaking infections, which means people test positive for COVID-19 when they are fully vaccinated.

These groundbreaking COVID-19 cases don’t prove vaccines don’t work, experts said, but are normal and expected. All the evidence suggests that even in the face of the new, highly transmissible delta variant, COVID vaccines still work as they should to dramatically reduce the risk of hospitalization and death.

© J. Scott Applewhite / AP

“When you hear about a breakthrough infection, it doesn’t necessarily mean the vaccine is failing,” Dr. Anthony Fauci, director of the US National Institute of Allergy and Infectious Diseases, told Congress Tuesday.

COVID-19 vaccines are very effective, but they do not block the virus 100% of the time, which means that some emerging infections occur after vaccination.

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“I think people should understand when you talk about breakthrough infections that the original data from the clinical trial – the efficacy data was based on the prevention of clinically apparent disease, not the prevention of a disease. infection, such as symptomatic infection, ”Fauci said.

© J. Scott Applewhite / AP
Infectious disease specialist Dr Anthony Fauci responds to accusations by Senator Rand Paul, R-Ky., As he testifies before the Senate Committee on Health, Education, Work and Pensions, on Capitol Hill in Washington on Tuesday, July 20, 2021.

Despite many high-profile cases of breakthrough infections with mild or no symptoms, including among Olympic athletes and some politicians, the overall number is very low compared to the number of people vaccinated.

And the number of people hospitalized or dying after being fully immunized is even lower, according to the U.S. Centers for Disease Control and Prevention (CDC) and State Health Services. This demonstrates that vaccinated people are much less likely to die from COVID-19 than unvaccinated people.

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This does not mean that serious illness resulting from infection is not possible, but it does tend to occur in the elderly or otherwise immunocompromised, experts said.

“Of the 157 million fully vaccinated in the United States, there have been 4,909 hospitalizations and 988 deaths,” said Dr. Carlos del Rio, an infectious disease physician and professor of medicine in the Division of Infectious Diseases at the Faculty of medicine from Emory University, at a press conference. briefing Monday.

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MANILA, PHILIPPINES – JULY 20: A healthcare worker prepares a photo of Sinovac Biotech’s CoronaVac COVID-19 vaccine during a mass vaccination for public transport workers on July 20, 2021 in Manila, Philippines.

“Of course we will see breakthrough infections that lead to serious illness, more in vulnerable populations with underlying chronic illnesses that could not respond to vaccines because they could not,” Dr. John Brownstein, epidemiologist of infectious diseases at Boston’s Children’s Hospital and an ABC News contributor, told ABC News.

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Although studies on this are not complete, Fauci said last week that the risk of a vaccinated person transmitting COVID to someone else is definitely much lower than that of an unvaccinated person spreading COVID.

“You can make a reasonable assumption that the rate of transmissibility from the asymptomatic vaccinated person to an uninfected person would be less likely than if the person were not vaccinated,” Fauci said during a team briefing. White House COVID-19 response last week.

The overall number of breakthrough infections is increasing, but it could be because more people overall are getting vaccinated, resulting in more breakthrough cases, associate professor and expert Dr Shobha Swaminathan told ABC News. in Infectious Diseases at Rutgers New Jersey Medical School. .

“As the number of infections in the United States increases, there could be a slight increase in the number of ‘breakthrough’ infections,” Swaminathan said. “However, the majority of infections continue to be reported among those who have not been vaccinated.”

Experts have said that the delta variant could contribute to these cases, but for now, research is ongoing.

“Whether this causes an increase in the rate of breakthrough infections, it’s unknown,” adds Brownstein.

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WASHINGTON, DC – JULY 20: Rochelle Walensky, director of the Centers for Disease Control and Prevention (CDC), left, and Dr Anthony Fauci listen to a hearing of the Senate Committee on Health, Education, Labor and pensions.

But experts take comfort in what they know, that even with the highly transmissible delta variant sweeping the country, more than 99% of deaths from COVID-19 are among unvaccinated people.

“In some parts of the country the percentage is even higher, especially in areas with low vaccination rates,” CDC director Dr. Rochelle Walensky said Tuesday during a hearing on Capitol Hill. “The best way to stop the spread is with vaccines.”

Alexis E. Carrington, MD is an associate producer in the ABC News medical unit and a growing dermatology resident at George Washington University. Sony Salzman is the coordinating producer for the ABC News medical unit.