‘Walking Dead’ actor Kelley Mack’s death fuels COVID-19 vaccine conspiracy theory
Kelley Mack, an actor who starred in “The Walking Dead,” died due to complications from the COVID-19 vaccine.
Actor Kelley Mack, who was best known for playing Addy on the TV show “The Walking Dead,” died at age 33 on Aug. 2, 2025, her sister announced in an Instagram post.
Following the announcement, some people online speculated that Mack died due to complications from the COVID-19 vaccine.
“It seems that Kelly Mack was ‘fully vaccinated,'” an X user wrote (archived) on Aug. 6. Another X user wrote (archived), “Of course this is totally unrelated to this young woman’s untimely death at 33yo, but as were most in her field, Actress Kelly [sic] Mack was fully vaccinated with the ‘Safe & Effective’ COVID-19 Vaccine.”
Some posts also alleged Mack battled “turbo cancer,” an informal term some people have used to describe what they claim are aggressive cancers linked to COVID-19 vaccinations.
However, Mack’s family confirmed she died after a battle with a type of cancer called glioma of the central nervous system. Her family did not attribute her death to COVID-19 vaccinations — and scientific evidence does not support claims linking vaccines to “turbo cancer.” Therefore, we’ve rated this claim false.
Mack’s sister publicly announced her death in an Instagram post shared on Aug. 5, 2025, writing:
It is with indelible sadness that we are announcing the passing of our dear Kelley. Such a bright, fervent light has transitioned to the beyond, where we all eventually must go.
Kelley passed peacefully on Saturday evening with her loving mother Kristen and steadfast aunt Karen present. Kelley has already come to many of her loved ones in the form of various butterflies 🦋❤️. She will be missed by so many to depths that words cannot express.
Kelley’s Caringbridge link in her bio includes the 2-page formal announcement with information on her upcoming life celebration in Ohio on August 16th. She would want you all to know how much she loves you. And as her sister, I want you all to know how brave that tough SOB was, especially when she decided to make the leap to be reunited with God. I’m so f—— proud of her.
The link in Mack’s bio directed us to the formal death announcement on CaringBridge’s website.
Mack died in Cincinnati after battling glioma of the central nervous system, according to the announcement. Like the Instagram post, the formal death announcement included no mention of complications related to COVID-19 vaccinations. The death announcement also included details about Mack’s upbringing, her acting career and her hobbies.
Mack first shared her glioma diagnosis in an Instagram post on Jan. 3, 2025. She said she had “persistent lower back pain” after moving into a new apartment with her boyfriend, Logan, in September 2024 and thought she had “slipped a disc.” Mack then began to experience “neuropathic itching” in her right quad, and “shooting pains” in her legs and back that made lying down in bed too painful, she said.
Emergency MRIs conducted the day before Thanksgiving 2024 revealed an abnormal mass on Mack’s spinal cord, ultimately leading to a diagnosis of an “extremely rare” type of cancer called diffuse midline glioma, she said. Due to a biopsy surgery on her spinal cord, Mack lost the use of her right leg and most of her left leg, she said.
Diffuse midline gliomas are “fast-growing” primary central nervous system tumors, meaning they begin in the brain or spinal cord, the National Cancer Institute explains. The exact cause of diffuse midline gliomas is unknown, though people with gene changes that can be passed down through families are at an increased risk, according to the NCI.
Symptoms of diffuse midline gliomas depend on the tumor’s location, the NCI says. They can include double vision, problems swallowing, weakness on one or both sides of the body, loss of balance and numbness, among others.
Health experts debunk ‘turbo cancer’ claims
Multiple leading health experts, including the NCI and the Mayo Clinic, have debunked claims that the COVID-19 vaccine can cause cancer.
Some backers of the “turbo cancer” conspiracy theory have claimed that the mRNA in COVID-19 vaccinations could alter a person’s DNA, resulting in cancer. However, there is no evidence to support that claim.
“None of the vaccines interact with or alter your DNA in any way. They cannot cause cancer. There is no truth to the myth that somehow the COVID-19 vaccine could inactivate the genes that suppress tumors,” Memorial Sloan Kettering Cancer Center says on its website.
The NCI agrees, writing, “There is no evidence that COVID-19 vaccines cause cancer, lead to recurrence, or lead to disease progression. Furthermore, COVID-19 vaccines do not change your DNA (i.e., your genetic code).”
The Mayo Clinic also says that COVID-19 shots are “not linked to a rise in cancer or more aggressive cancer,” adding that “researchers looked at the large groups of people who got a COVID-19 vaccine” and found “there is no evidence to support this myth.”
For further reading, Snopes also debunked a claim that famed heavy metal singer Ozzy Osbourne died from years of illness caused by the COVID-19 vaccine.
