By Jim Williams

CHICAGO (CBS) — The COVID vaccines aren’t working for everyone.

A viewer reached out to CBS 2’s Jim Williams to say after two shots of Pfizer, she’s still not protected.

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And she’s not alone.

Some people are taking drugs to fight cancer, but in some cases those drugs are blocking the effectiveness of the vaccine.

A lump on Pati Weddington’s cheek appeared seven years ago.

“At first they just thought it was nothing,” Weddington said. “And then all of sudden in a couple of months it got big and big so I had to go in and get it checked.”

It was leukemia, cancer of the blood-forming tissues.

“I just recently had gotten divorced and I was scared,” Weddington said. “I had little kids. It was just a scary time.”

She is in remission now and doing well. This year, she got two shots of the Pfizer COVID vaccine. But then she received some disturbing news.

“When I went to my doctor she did a blood test, she found I had no antibodies. My body didn’t let it occur,” Weddington said.

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Her doctor said the drug Ibrutinib, which Pati is taking to fight the leukemia, is working against the vaccine.

Ibrutinib is what’s called a BTK inhibitor.

“At this time, we know that some blood cancer can be immunosuppressive, so that can cause a low antibody response.  BTK inhibitors may cause further inability to produce antibodies to COVIS-19.  This is an active area of investigation,” said Doctor Lee Greenberger, Chief Scientific Officer of the Leukemia and Lymphoma Society.

“She said they’re finding Ibrutinib is blocking the vaccine from forming antibodies against COVID,” Weddington said.

Doctor Sajal Tanna of the Northwestern Medical School, who is not treating Pati, said it is common for vaccines to be less effective in protecting people with compromised immune systems.

And researchers are looking for answers.

“The questions that are being answered by these studies are what is the antibody effects on these patients who have these cancers and are on these therapies,” Tanna said. “What is the response like? What is the immunity like? Then once we know that answer, then we can look into how we can boost that immunity even further.”

Pati Weddington wants others in her position to know the risks.

“I think awareness to the public and awareness to other people who are in my situation that might not even know about it.”

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Doctors recommend people like Pati protect themselves by masking up and take some comfort in knowing that more and more of us are getting vaccinated, putting Pati less at risk.