A third vaccine dose generally increases protection from COVID-19 in patients with cancer, but effectiveness varies, according to a large study published in the European Journal of Cancer.

Researchers found that a third vaccine dose provided low levels of protection against infection and hospitalization among patients with lymphoma. 

In general, patients with solid tumors were better protected by a third vaccine dose than were patients with hematologic malignancies. Still, patients with cancer had a higher risk of COVID-19-related hospitalization and death when compared with the general population.  


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Researchers conducted this population-based study using data from individuals who participated in the third-dose vaccine booster program in the United Kingdom between December 2020 and December 2021. 

The researchers analyzed data from 87,039,743 SARS-CoV-2 PCR tests performed in 29,929,073 people. There were 2,258,553 PCR tests done in 361,098 patients with cancer. A total of 8,371,139 individuals received a third vaccine dose, and 230,666 of these patients had cancer.

Most patients received the Pfizer-BioNTech vaccine. The data showed no difference in vaccine effectiveness between patients whose primary series was with the AstraZeneca vaccine or the Pfizer-BioNTech vaccine. The number of patients who received the Moderna vaccine was insufficient for analysis.

Effectiveness by Dose and Cancer Type

A third vaccine dose improved all effectiveness endpoints among patients with cancer. Effectiveness against breakthrough infections increased from 43.5% after 2 vaccine doses to 59.1% after 3 doses. There was an increase in effectiveness against symptomatic infections (46.1% to 62.8%), hospitalization (73.0% to 80.5%), and death (88.9% to 94.5%) as well. 

The control group also experienced an increase in effectiveness from the second to the third dose, for breakthrough infections (54.0% to 77.3%), symptomatic infections (55.7% to 80.5%), hospitalization (80.3% to 89.8%), and death (83.3% to 91.6%).

After the third dose, vaccine effectiveness among patients with solid tumors was 66.0% for breakthrough infections and 69.6% for symptomatic infections. The effectiveness for breakthrough and symptomatic infections among patients with hematologic malignancies was lower, at 53.2% and 56.0%, respectively.

A third vaccine dose was the least effective for patients with lymphoma. Effectiveness was 10.5% for breakthrough infections and 13.6% for symptomatic infections. Effectiveness against hospitalization and death were 23.2% and 80.1%, respectively.

Patients who received their cancer diagnosis within 1 year before SARS-CoV-2 infection, those who had undergone recent systemic anticancer therapy, and those who received radiation therapy also experienced lower vaccine effectiveness.

Overall, despite the increase in vaccine effectiveness after the third dose, patients with cancer remained at an increased risk of COVID-19-related hospitalization (odds ratio [OR], 3.38; P <.001) and death (OR, 3.01; P <.001), compared with the control group.

“Cancer patients, and particularly those with lymphoma, should be encouraged to take additional measures to reduce their risk of infection when community prevalence and transmission are high,” the researchers wrote.

Reference

Lee LYW, Ionescu MC, Starkey T, et al. COVID-19: Third dose booster vaccine effectiveness against breakthrough coronavirus infection, hospitalisations and death in patients with cancer: A population-based study. Eur J Cancer. Published online July 12, 2022. doi:0.1016/j.ejca.2022.06.038

This article originally appeared on Cancer Therapy Advisor