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COVID-19 Breakthrough Infection: Should you be Worried?

Published on Aug. 23, 2021

Vaccines are highly effective in the fight against COVID-19. While rare, it is possible for fully vaccinated people to still get infected. These cases are called vaccine breakthrough infections. It's important to note that while vaccines work to prevent serious illness, no vaccine prevents sickness 100% of the time.

“We are seeing breakthroughs, but they continue to be rare,” said Christopher Ledtke, MD Munson Healthcare Infectious Disease Section Chief. “Less than 1% of fully vaccinated individuals develop COVID-19, even in the setting of the Delta surge. The infections in breakthrough cases are typically mild. It is extremely unlikely to develop a hospitalization or death if fully vaccinated.”


Is the Delta variant really more contagious than prior strains?

Unlike prior strains, the Delta variant is highly contagious. Even vaccinated people can spread the virus, leading to more COVID-19 infections, especially to those who are unvaccinated. 

Dr. Ledtke explains that as the severity of illness increases, the protection the vaccine offers also increases.

“We know that our vaccines work well, even for Delta,” said Dr. Ledtke. “90% of new cases are in unvaccinated individuals and over 95% of hospitalizations are in unvaccinated individuals.”

Getting vaccinated is more important now than ever before with the highly transmissible Delta variant making up the majority of new COVID-19 cases seen here in northern Michigan.


Why are breakthrough cases increasing?

Dr. Ledtke explains that as we are seeing an increase in the number of people who are vaccinated, the number of breakthrough cases will also increase. For example, if the risk of a vaccinated person experiencing a breakthrough case of COVID-19 is 1%, and the vaccinated population is 1,000 people, then 10 people would develop a breakthrough case. If the vaccinated population rises to 100,000 people, then about 1,000 people would develop a breakthrough infection in that population.

“That's the nature of statistics,” explains Dr. Ledtke. “As the population of vaccinated folks gets larger, the more documented breakthroughs will be reported.”


If breakthrough infection is possible, why vaccinate?

“Vaccines are very effective and prevent COVID-19 in almost everyone,” said Joe Santangelo, MD, Munson Healthcare Chief Quality and Safety Officer. “Of the people who are getting COVID-19 after being vaccinated, most are having a much milder course than they would have if they didn’t get vaccinated in the first place. This is common in all vaccines, and this is partly why sometimes we have to get boosters for certain vaccines — because they lose effectiveness over time.”

In short, getting vaccinated against COVID-19 is one of the best ways to build community immunity and prevent yourself from experiencing severe symptoms.

Why You Should Get  the COVID-19 Vaccine

How can I keep myself and my loved ones safe?

The combination of getting vaccinated and wearing a mask continues to be the best way to protect yourself from COVID-19. In addition, frequent handwashing and social-distancing are proven ways to help prevent COVID-19.


Questions about breakthrough infections?

Ask a nurse! Munson Healthcare’s Ask-A-Nurse line is available to you every day from 7 am to 11 pm by calling 231-935-0951. A team of registered nurses is here for you to answer any questions you have, whether they are related to COVID-19 or any other health topic, free of charge.

Ask-A-Nurse   231-935-0951