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People Receiving Cancer Treatment Develop ‘Adequate’ Immune Response to Pfizer COVID-19 Vaccine

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Nearly all the people in a clinical trial who were receiving systemic intravenous cancer treatment had an adequate immune response to the Pfizer-BioNTech COVID-19 vaccine, according to an Israeli study.

The research was published online on May 28, 2021, by the journal JAMA Oncology. Read the abstract of “Evaluation of Seropositivity Following BNT162b2 Messenger RNA Vaccination for SARS-CoV-2 in Patients Undergoing Treatment for Cancer.” (BNT162b2 messenger RNA vaccine is the chemical name of the Pfizer-BioNTech vaccine.)

Systemic cancer treatments affect the whole body by going through the bloodstream. They’re given intravenously, which means they’re delivered directly into your bloodstream through an IV or a port. Chemotherapy medicines, a number of targeted therapy medicines, and immunotherapy medicines are systemic treatments.

For this study, “seropositivity” means the people in the study had COVID-19 antibodies in their blood.

About the Pfizer-BioNTech COVID-19 vaccine
About the study
What this means for you

About the Pfizer-BioNTech COVID-19 vaccine

The Pfizer-BioNTech vaccine works by using genetic material called messenger RNA (mRNA). The mRNA vaccines contain a small piece of the coronavirus’s mRNA, which tells your body to make copies of a protein in the virus called the spike protein. Your immune system then builds up immune cells and antibodies to fight the spike protein. So, if you’re exposed to the COVID-19 virus, your immune system recognizes the virus and protects you from infection.

Because mRNA is just a small piece of the virus copied in a lab, the vaccine cannot cause COVID-19 and is considered safe for people with weakened immune systems — including people being treated for cancer.

The U.S. Food and Drug Administration (FDA) has found that these vaccines are safe and highly effective for preventing COVID-19, especially serious illness and death from the disease. It is still unclear how long the protection lasts and whether you can spread COVID-19 to someone else if you are exposed to the virus after being vaccinated.

Experts have recommended that most people who have been diagnosed with cancer or have a history of cancer should get a COVID-19 vaccine. Still, you should talk to your doctor about whether getting vaccinated is the right decision for your individual situation.

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About the study

People who are currently being treated for cancer — including breast cancer — have a higher risk of severe illness if they’re diagnosed with COVID-19.

In the first studies on the effectiveness of the Pfizer-BioNTech COVID-19 vaccine, less than 4% of the people in the study had cancer. It was unclear how well the vaccine would work in people being treated for cancer.

The researchers did this study to look specifically at how effective the Pfizer-BioNTech vaccine is in people who have been diagnosed with cancer.

Of the 180 people who participated in the study:

  • 102 were getting intravenous cancer treatment
  • 78 had not been diagnosed with cancer

Both groups of people received both doses of the Pfizer-BioNTech vaccine and got the second dose at least 12 days before they joined the study.

All the people diagnosed with cancer were being treated at the Davidoff Cancer Center in Petah Tikva, Israel.

Of the people diagnosed with cancer:

  • 58 were men and 44 were women
  • half were older than 66 and half were younger
  • 29 had gastrointestinal cancer, 26 had lung cancer, 18 had breast cancer, 9 had brain cancer, 8 had genitourinary cancer, and 12 had some other type of cancer
  • 26 had early-stage disease and 76 had metastatic disease, meaning the cancer had spread to other parts of the body away from the original site

Of the people diagnosed with cancer getting a variety of systemic treatments:

  • 30 were receiving chemotherapy
  • 22 were receiving immunotherapy
  • 20 were receiving chemotherapy and targeted therapy
  • 14 were receiving chemotherapy and immunotherapy
  • 11 were receiving targeted therapy
  • 5 were receiving immunotherapy and targeted therapy

The researchers compared seropositivity levels between the two groups and found that:

  • 90% of the people being treated for cancer were seropositive for COVID-19 antibodies
  • 100% of the people who did not have cancer were seropositive for COVID-19 antibodies

Still, the actual levels of COVID antibodies were lower in the people diagnosed with cancer compared with the people who did not have cancer. Antibody levels were as follows:

  • 1,931 AU/ml in people diagnosed with cancer
  • 7,160 AU/ml in people who did not have cancer

The researchers found that, among people diagnosed with cancer, people being treated with chemotherapy and immunotherapy and people being treated with immunotherapy and targeted therapy had the lowest antibody levels.

“As the correlation between antibody levels after vaccination and clinical protection has not yet been established, further research is required to determine the magnitude and duration of protection the vaccine provides to patients with cancer,” the researchers wrote. “Nonetheless, our findings do suggest that vaccinating such patients during anticancer treatment of any kind should be top priority.”

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What this means for you

If you’re currently being treated for breast cancer and are worried about how effective a COVID vaccine may be for you, this study offers reassuring results.

While the levels of antibodies were lower in people getting cancer treatment, it’s good to know that 90% of the people diagnosed with cancer had COVID antibodies.

And — as the researchers noted in the paper — some people who have been diagnosed with cancer are reluctant to visit medical centers for treatment or participate in clinical trials because they’re afraid of being exposed to COVID-19.

“The confidence of patients with cancer in their ability to be effectively vaccinated may help address both issues,” they said.

There are other ongoing studies looking at how people diagnosed with cancer respond to COVID-19 vaccination. These studies will provide important information on how effective the vaccines are for people who are being treated for cancer, as well as how long protection from COVID-19 lasts.

Stayed tuned to Breastcancer.org Research News for the latest information on COVID-19 vaccines for people diagnosed with cancer.

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Written by: Jamie DePolo, senior editor


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