Do Patients With Cancer Require Additional COVID-19 Vaccine Doses?

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Findings from a Spanish study on the effectiveness of vaccines against COVID-19 infection among patients with cancer recommend administering additional doses of the vaccine to this at-risk population. These data were published by Neto et al in Nature Communications.

Patients with cancer are at an increased risk of death from COVID-19 infection, especially those who have lung cancer, hematologic malignancies, or are undergoing systemic cancer treatment such as chemotherapy.

The participation of patients with active cancer in clinical trials that have been carried out to test the effectiveness of COVID-19 vaccines has been very limited, so it has not been possible to know the exact effectiveness of immunization against the SARS–CoV-2 virus among this risk group. However, prospective data from several studies show that patients with cancer may develop fewer protective antibodies to the virus than the general population—especially after receiving a single dose of the vaccine.

Real-World Data

The new study published in Nature Communications confirms these results, based on a large analysis of data obtained from clinical registries. The study authors believe this is the most comprehensive work yet on this issue, and the first of its kind with information from real-world data, providing a more realistic view of how vaccines are working in everyday clinical practice among people with cancer.

The researchers analyzed data from nearly 185,000 patients with cancer included in the Information System for the Development of Research in Primary Care (SIDIAP), a database that includes people treated at the first level of care in the Catalonia region of Spain. Half of the individuals included in the study (n = 92,372) had received at least the first complete immunization, defined as two inoculations of the vaccine, and the other half (n = 92,372) had not been vaccinated at the time of the analysis.

Researchers compared mortality data and serious complications derived from COVID-19 infection among the immunized group after receiving the first and second doses of the vaccine with those of the unvaccinated group. Next, the researchers compared the results of the members of the experimental group after having received the booster dose of the vaccine (n = 54,267) with an equivalent sample of people in the control group who had only received the first two inoculations.

The results of the study showed that the rate of mortality and serious complications among patients with cancer who were not vaccinated against COVID-19 was twice that compared to patients who received the full first dose. However, this difference was smaller than the observed data among the general population immunized against SARS–CoV-2 and the nonimmunized population.

Patients had 51.8% (95% confidence interval [CI] = 40.3%–61.1%) and 58.4% (95% CI 29.3%–75.5%) protection against hospitalization and death from COVID-19, respectively, after full vaccination (two doses), and 77.9% (95% CI 69.2%–84.2%) and 80.2% (95% CI 63.0%−89.4%) after a booster dose. Compared to primary vaccination, the booster dose provided higher peak protection against the virus during follow-up. 

“Our results clearly demonstrate that vaccination against COVID-19 significantly reduces mortality and serious complications among patients [with cancer], especially those who have received the booster dose,” highlighted study author Otavio Ranzani, MD, PhD, of the Barcelona Institute for Global Health, who supervised the study together with Talita Duarte-Sallés, PhD, of Institut Universitari d’Investigació en Atenció Primària.

The study authors concluded, “Our results confirm the role of primary and booster COVID-19 vaccination in preventing COVID-19 severe events in patients with cancer and highlight the need for the additional dose in this population.”

Disclosure: For full disclosures of the study authors, visit

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.