Cancer Patients Have Unique Considerations When Receiving COVID-19 Vaccines



Patients undergoing chemotherapy had lower COVID-19 antibody levels than patients undergoing targeted therapy after vaccination.

In addition to not achieving full immunity with the primary 1 or 2 doses of COVID-19 vaccines available, the type of cancer treatment patients receive could influence the response they have, according to a pair of recent studies. .

The first study, published in Natural medicine1 by researchers at the University of Arizona Health Sciences, found that patients undergoing active chemotherapy had a weaker immune response to 2 doses of the COVID-19 vaccine. However, according to a press release, researchers found that a third dose increased patients’ response.1

“We wanted to make sure we understood the level of protection that COVID-19 vaccines provide for our cancer patients, especially as restrictions were relaxed and more contagious variants began to spread,” Rachna Shroff said. , MD, MS, chief of gastrointestinal medical oncology at UArizona Cancer Center, in press release.1

A team of investigators analyzed 53 patients receiving active immunosuppressive cancer therapies, such as chemotherapy, to compare immune responses after the first and second dose of Pfizer-BioNTech COVID-19 vaccine with responses from 50 adults in good health.1

After 2 doses of the vaccine, most cancer patients showed some immune response to the vaccine, meaning they had antibodies to SARS-CoV-2, according to the study.1

“We were pleasantly surprised,” researcher Deepta Bhattacharya, PhD, said in the press release. “We looked at the antibodies, B cells, and T cells, which make up the body’s defense system, and found that the vaccine is likely to be at least partially protective for most people on chemotherapy.”1

However, the researchers noted that the immune response in cancer patients was much weaker than responses in healthy adults, and a few of the patients had no response at all. This results in less protection against SARS-CoV-2 and in particular the Delta variant, which is now the dominant strain in the United States.1

Twenty patients returned for a third dose of the vaccine, and most of those recipients had an enhanced immune response, according to the study. The group’s overall immune response after the third injection reached levels similar to that of healthy adults after 2 doses. Notably, the researchers said they focused on patients with solid tumors, such as breast or gastrointestinal cancer, and excluded patients receiving immunotherapy.1

In the second study, published in JAMA Oncology, researchers found that the type of cancer treatment influences patients’ vaccine response. Specifically, patients undergoing chemotherapy had lower antibody levels than patients undergoing targeted therapy, according to the study.2

Austrian and Italian researchers studied antibody production after COVID-19 vaccination in more than 600 participants. Patients were divided into 2 groups — those with solid tumors and blood cancers — as well as a control group made up of healthy hospital staff. According to the study, researchers found that the form of cancer treatment influences the level of immune response to the vaccine.2

“Patients receiving chemotherapy had lower antibody levels than patients receiving targeted therapy,” said lead author Maximilian Mair, MD, in the press release. “We found the lowest antibody levels in blood cancer patients who received targeted therapy against malignant B cells.”2

In the healthy control arm and cancer patients, researchers found that antibody levels were higher after full immunization with COVID-19 vaccines than after a single dose. However, even after a full vaccination, antibody levels were higher in healthy individuals than in cancer patients. No differences were found between the different vaccines, although the researchers noted that most of the patients had received mRNA vaccines.2

“Overall, our data show that most cancer patients develop antibodies to the SARS-CoV-2 spike protein after vaccination and therefore vaccination is generally recommended, but vaccine protection is reduced by some. cancer treatments, ”said Matthias Preusser, MD, study leader. in the press release. “Even after vaccination, general protective measures such as regular COVID testing and hygiene measures therefore appear to be very important, especially for cancer patients receiving ongoing cancer treatment, if optimal protection against COVID-19 must be obtained. “2


1. Cancer patients on chemotherapy are probably not fully protected by the COVID-19 vaccine, study finds. Press release. Arizona University of Health Sciences; September 30, 2021. Accessed October 8, 2021.

2. Coronavirus vaccination in cancer patients: the type of cancer treatment influences the vaccine response. Press release. EurekAlert; October 1, 2021. Accessed October 8, 2021.


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