Patients With Cancer Have Unique Considerations When Receiving COVID-19 Vaccines


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

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

The first study, published in Nature Medicine1 by researchers at the University of Arizona Health Sciences, found that patients undergoing active chemotherapy had a lower immune response to 2 doses of the COVID-19 vaccine. However, according to a press release, the researchers found that a third dose increased patients’ response.1

“We wanted to make sure we understand the level of protection the COVID-19 vaccines are offering our cancer patients, especially as restrictions were being eased and more contagious variants were starting to spread,” said Rachna Shroff, MD, MS, chief of gastrointestinal medical oncology at the UArizona Cancer Center, in the press release.1

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

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

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

However, the researchers noted that the immune response among patients with cancer was much lower 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 especially 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 these recipients had an increased immune response, according to the study. The overall group immune response after the third shot reached levels similar to those of healthy adults after 2 doses. Notably, the researchers said that 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, investigators 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

Researchers in Austria and Italy studied antibody production following COVID-19 vaccination in more than 600 participants. The patients were split into 2 groups—those with solid tumors and blood cancers—as well as a control group of healthy hospital staff. According to the study, the 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 patients with blood cancers who had received targeted therapy against malignant B cells.”2

In both the healthy control arm and the patients with cancer, the researchers found that antibody levels were higher after full immunization with the COVID-19 vaccines than after only 1 dose. However, even after full vaccination, antibody levels were higher in healthy individuals than in patients with cancer. No differences were found between the various vaccines, although the researchers noted that most patients received mRNA vaccines.2

“Overall, our data show that most cancer patients develop antibodies against the SARS-CoV-2 spike protein after vaccination and therefore vaccination is generally recommended, but that vaccine protection is reduced by some cancer treatments,” said study lead Matthias Preusser, MD, 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 is to be achieved.”2


1. Cancer Patients on Chemotherapy Likely Not Fully Protected by COVID-19 Vaccine, Study Finds. News release. University of Arizona Health Sciences; September 30, 2021. Accessed October 8, 2021.

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

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