• COVID-19

    COVID Queries: Delta breakthrough infections

several laboratory vials labeled COVID-19 Coronavirus SARS-CoV-2 Vaccine in a delivery box

Q: Even people who have been vaccinated are getting sick with the delta variant, so why should I bother getting the shot?

A: COVID-19 vaccines remain the best defense against COVID-19. By and large, it's the patients who have not been vaccinated who are getting the most severe disease from the delta variant.

"There isn't a vaccine that is 100% effective at preventing illness," says Martin Herrmann, M.D., medical director of Mayo Clinic Health System in Waseca and New Prague. "Breakthrough cases of COVID-19 are going to happen, but the percentage is small. Also, the disease in vaccinated people tends to be much less severe than the diseases in unvaccinated people."

These breakthrough hospitalizations tend to happen in people with weaker immune systems who might not have the same lasting protection from the vaccine.

The delta variant surge is far from behind us and is likely to continue to accelerate, particularly in communities with lower rates of vaccination. Going into the fall and winter, it will be difficult to predict exactly what's going to happen with the virus, including the emergence of additional variants.

The best chance of avoiding another wave of the virus is for as many people as possible to get vaccinated.


Mayo Clinic Health System consists of clinics, hospitals and other facilities that serve the health care needs of people in Iowa, Minnesota and Wisconsin. The community-based providers, paired with the resources and expertise of Mayo Clinic, enable patients in the region to receive highest-quality physical and virtual health care close to home.

Information in this post was accurate at the time of its posting. Due to the fluid nature of the COVID-19 pandemic, scientific understanding, along with guidelines and recommendations, may have changed since the original publication date

For more information and all your COVID-19 coverage, go to the Mayo Clinic News Network and mayoclinic.org.

Learn more about tracking COVID-19 and COVID-19 trends.

Sept. 16, 2021- Mayo Clinic COVID-19 trending map using red color tones for hot spots

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