Labels Matter: Breakthrough Infections

During the early stages of the COVID pandemic, both the CDC and FDA used certain words or phrases that inadvertently frightened or confused the American public.

On February 13, 2024, National Geographic Press will be publishing a book I wrote called, TELL ME WHEN IT’S OVER: AN INSIDER’S GUIDE TO DECIPHERING COVID MYTHS AND NAVIGATING A POST-PANDEMIC WORLD. Before publication, I will be writing about various issues discussed in that book.

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COVID vaccines were first available in December 2020. Unfortunately, one phrase used to describe an early outbreak confused the public about what COVID vaccines could or couldn’t do.

July 2021

Breakthrough Infections

On July 4, 2021, thousands of men gathered in Provincetown, Massachusetts, to celebrate Independence Day. Most had received two doses of a COVID vaccine. Nonetheless, 346 men who had been fully vaccinated developed COVID; 4 (1.2 percent) were hospitalized. The 342 men who weren’t hospitalized developed either asymptomatic or mild infections. The COVID vaccines were doing what they were supposed to do—keeping these men out of the hospital, out of the intensive care unit, and out of the morgue.

This was an opportunity for the CDC to celebrate how well these vaccines were working. Unfortunately, the CDC’s report of the Provincetown outbreak gave birth to a term that misled the public. The description of the outbreak, which appeared in a CDC publication called Morbidity and Mortality Weekly Report, was titled, “Outbreak of SARS-CoV-2 Infections, Including COVID-19 Vaccine Breakthrough Infections, Associated with Large Public Gatherings—Barnstable County, Massachusetts, July 2021.” This was the first time that mild or asymptomatic infections had been described as “breakthrough infections.”

The word “breakthrough” implies failure. But COVID vaccines hadn’t failed. Quite the opposite: they had succeeded in keeping almost all these men out of the hospital. In its use of the word “breakthrough,” the CDC had inadvertently set a bar for COVID vaccines that was impossible to reach. From this point forward, public health officials and the media often discussed waning immunity without differentiating between waning protection against mild illness (which was inevitable) or waning protection against severe disease (which wasn’t). “I got the vaccine,” lamented some. “And I still got COVID. The CDC lied to me.”

A few months after the CDC reported the outbreak in Provincetown, Massachusetts, Supreme Court justice Brett Kavanaugh tested positive for COVID during a routine screening. He had no symptoms. The immediacy, breathlessness, and alarm with which the media covered his story, often using the CDC’s term “breakthrough,” caused some casual observers to conclude that Brett Kavanaugh must be fighting for his life. One politician got it right. Lindsey Graham, a Republican senator from South Carolina—who had received two doses of vaccine—suffered a short-lived COVID infection with mild sinusitis. “I am very glad I was vaccinated,” he said, “because without vaccination I am certain I would not feel as well as I do now. My symptoms would be far worse.” Right. Exactly right.

Respiratory viruses like influenza, respiratory syncytial virus (RSV), and SARS-CoV-2 have short incubation periods (i.e., the time from exposure to the development of symptoms). The immunity induced by vaccination or natural infection with these viruses will not protect against mild disease for long, usually only a few months at best. In its recent promotion of influenza vaccine, the CDC has done a much better job of explaining what these types of vaccines can and can’t do. The current influenza program employs the tag line, “Wild-to-Mild,” emphasizing that the goal of the influenza vaccine is to convert a severe (“wild”) disease to a mild one.

Although the COVID pandemic is over, SARS-CoV-2 virus is likely to be with us for years if not decades. Even those who are fully vaccinated will likely suffer the occasional mild infection. Without a reasonable understanding of the goal for COVID vaccines, we will be continually disappointed.