Breakthrough COVID-19 infections and booster vaccines

Apr 21, 2021 | Jennifer O'Hara | @jenohara | Comments (6)

Dr. Gregory Poland, an infectious diseases expert and head of Mayo Clinic's Vaccine Research Group says COVID-19 mutations and the virus spread are happening because of people who don't wear masks, who don't get vaccinated and who don't adhere to safety recommendations.

"I believe that we should be radically transparent and honest," says Dr. Poland. "The more time this virus passes through one person after another, the more likely it continues to mutate. As a result of those mutations, two things are happening. Some of the mutations are making vaccines and plasma monoclonal antibodies less effective. The other thing is that the virus will likely become something that we have to live with for the rest of our lives."

Dr. Poland reminds people that vaccine protection is not 100%. Breakthrough infections can occur.

"Remember that in the clinical trials, 95% means that compared to unvaccinated people, your risk is reduced by 95% — not 100%," he says. "You might have a mild case of COVID-19,but you can still spread it to others, including those who are immune compromised, such as cancer patients. That's why we continue to wear masks until we get very widespread immunization."

In this Mayo Clinic Q&A podcast, Dr. Poland talks more about breakthrough infections and the Johnson & Johnson COVID-19 vaccine pause, and he answers listeners questions.

To practice safe social distancing during the COVID-19 pandemic, this interview was conducted using video conferencing. The sound and video quality are representative of the technology used. For the safety of its patients, staff and visitors, Mayo Clinic has strict masking policies in place. Anyone shown without a mask was recorded prior to COVID-19 or recorded in an area not designated for patient care, where social distancing and other safety protocols were followed.

Read the full transcript.

Research disclosures for Dr. Gregory Poland.

Connect with others talking about the pandemic and supporting one another in the COVID-19 support group.

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

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I have a son and daughter-in-law that fear their sixteen year old daughter getting the vaccine for fear she will become infertile. What is your feeling on this issue?


I have a son and daughter-in-law that fear their sixteen year old daughter getting the vaccine for fear she will become infertile. What is your feeling on this issue?

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Hi @pcarl1938, according to the CDC and other health professionals, there is currently no evidence that any vaccines, including COVID-19 vaccines, cause fertility problems.

Unfortunately, there has been sophisticated disinformation campaign circulating on social media channels, claiming that antibodies to the spike protein of COVID-19 produced from these vaccines will bind to placental proteins and prevent pregnancy. COVID-19 vaccines have not been linked to infertility or miscarriage.

You can read more from Mayo Clinic experts in this article. See myth number 9.
– COVID-19 vaccine myths debunked

I hope this puts your son and daughter-in-law's minds at ease.


Dr. Poland. What will be the deciding factor of the time of year when boosters will be most effective since people have gotten COVID-19 and it's variants year round?


Dr. Poland – could you share some insight on why there isn’t more research being done to find easily accessible therapeutics for people who do contract the virus? Since the vaccine provides little or no protection for immunocompromised, transplant patients we need to know we can have easy access to treatment if we do happen to contract the virus. And why would we consider a third vaccine (booster) if the first two aren’t effective?
We can’t continue to live in fear and isolation. People who have little or no risk of severe illness are being asked to vaccinate while those who are at greater risk for serious illness aren’t protected. This doesn’t make sense.


Excellent questions @merpreb and @ladydidehart. They have been submitted for an upcoming podcast with Dr. Poland.

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