Cancer patients on active treatment had a “pronounced lag” in antibody production after receiving the Pfizer-BioNTech COVID-19 vaccine, researchers reported in JAMA Oncology.

The rate of seropositivity after the first vaccine dose was significantly lower in cancer patients than in control individuals. However, the seropositive rate increased substantially in cancer patients after they received the second dose.

For this study, researchers evaluated the effects of the Pfizer-BioNTech vaccine (BNT162b2) in 232 patients receiving active treatment for cancer and in 261 age-matched health care workers.

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Cancer types included gastrointestinal (n=63), genitourinary (n=48), lung (n=45), breast (n=42), gynecologic (n=11), head and neck (n=11), and neurologic (n=5) cancers, as well as melanoma (n=5) and sarcoma (n=2).

The cancer patients received their treatment after the first and second doses of the vaccine. Treatment types included chemotherapy (n=134), biological agents (n=81), and immunotherapy (n=83).

After the first vaccine dose, 29% of cancer patients were seropositive, compared with 84% of control individuals (P <.001). However, the rate of seropositivity increased to 86% in cancer patients after the second vaccine dose.

There were 2 cases of COVID-19 documented after the first dose in the cancer patients, but there were no other COVID-19 cases recorded during the study period.

The most common local reaction observed in the cancer patients was pain at the injection site (69%). Less common reactions included injection site warmness (9%), redness (8%), or swelling (4%).

The most common systemic reactions in the cancer patients were fatigue (24%), muscle and joint pain (13%), and headache (10%).

“Our study lends credence to the widely adopted recommendation to prioritize patients with cancer for SARS-CoV-2 vaccination,” the researchers wrote. “Nevertheless, our results imply that a potential intention to decline a second vaccine by some jurisdictions owing to a shortage of vaccines warrants reevaluation of unique populations, such as patients with cancer, in view of lagging immunogenicity.”

Disclosures: This study was partially supported by an Israel Cancer Research Fund grant. One study author study author declared an affiliation with Pfizer. Please see the original reference for a full list of disclosures.


Goshen-Lago T, Waldhorn I, Holland R, et al. Serologic status and toxic effects of the SARS-CoV-2 BNT162b2 vaccine in patients undergoing treatment for cancer. JAMA Oncol. Published online July 8, 2021. doi: 10.1001/jamaoncol.2021/2675

This article originally appeared on Cancer Therapy Advisor