By Jonathan Goodman, MPhil

COVID-19 vaccines confer varying levels of protection in patients with cancer, according to research published in The Lancet Oncology.

Researchers found that overall vaccine effectiveness was lower in patients with cancer than in the general population, and effectiveness waned more quickly over time for patients with cancer. 

Vaccine effectiveness was lowest in patients with leukemia or lymphoma but highest in patients with myeloma, non-colorectal gastrointestinal cancer, or lung cancer. 

This study included data from 377,194 patients with cancer and 28,010,955 individuals from the general population. Data were derived from the UK Coronavirus Cancer Evaluation Project. 

The vaccinated patients had received 2 doses of the Pfizer-BioNTech vaccine, 2 doses of the Oxford-AstraZeneca vaccine, or a mix of vaccines.

A total of 42,882 patients in the cancer cohort and 5,748,708 individuals in the control population had breakthrough cases of COVID-19 after vaccination. 

The overall vaccine effectiveness rates were 65.5% in the cancer cohort and 69.8% in the control population. At 3 to 6 months after the second vaccine dose, the effectiveness had decreased more in the cancer cohort than in the general population — 47% and 61.4%, respectively. 

In the cancer cohort, vaccine effectiveness was lower in patients who had received systemic anticancer therapy than in those who had not. The overall effectiveness rates were 61.0% and 67.5%, respectively. At 3 to 6 months, the effectiveness rates were 36.6% and 51.1%, respectively.

Cancer patients who received radiotherapy had reduced vaccine effectiveness as well. The overall effectiveness rates were 59.8% in patients who had received radiotherapy and 66.5% in patients who had not. At 3 to 6 months, the effectiveness rates were 36.6% and 48.8%, respectively.

Overall vaccine effectiveness was lowest in patients with lymphoma (44.1%) or leukemia (45.1%) but highest in patients with myeloma (77.5%), non-colorectal gastrointestinal cancer (74.7%), or lung cancer (74.5%). 

At 3 to 6 months, vaccine effectiveness was lowest in patients with lymphoma (12.8%), leukemia (18.5%), or cancer of the lip, oral cavity, or pharynx (18.5%). Vaccine effectiveness was highest in patients with myeloma (63.9%), lung cancer (61.5%), or non-colorectal gastrointestinal cancer (60.5%).

“We have identified groups at high risk of breakthrough infections who can be prioritized for research or pandemic response interventions, early community treatment, or pre-exposure prophylaxis programs,” the researchers wrote. “Such measures will be crucially important as global health care and cancer care systems adapt to living with COVID-19 as an endemic disease.”

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