Authored by Dr. Brian Koffman
Bottom Line:
The COVID-19 mortality rate (MR) was lower in recently vaccinated cancer patients and the same was true for B-cell cancers.
Who Performed the Research and Where Was it Published:
M. Kelsey Kirkwood, MPH, was the lead author in the publication in JCO Oncology Advances in November 2024.
Background:
It is well established that cancer patients in general and CLL / SLL patients have higher mortality rates with COVID-19 infection. It is also well-established that those MRs have been falling. Hypothesized causes for the reduced risk include:
- Better therapies, including nirmatrelvir-ritonavir (Paxlovid), combined with a better understanding of how and when to treat the infection and subsequent inflammation.
- Milder disease since the Omicron phase.
- Increased immune response from prior infections and / or vaccinations.
This research examines recent vaccination as a factor in reducing the risk (hazard ratio) of dying from COVID-19.
While it was studying COVID-19 in all cancer infections, the supplemental materials provide some details on patients with B-cell hematologic malignancies, which would include many with chronic lymphocytic leukemia (CLL) but also include other lymphoma patients.
Methods and Participants:
Patients with cancer 18 years and older who tested positive for SARS-CoV-2 infection on or after April 1, 2021, were included who also had information on having received or not received at least one COVID-19 vaccine dose. Cohorts were divided into three vaccine exposure categories reflecting the timing of the last dose before SARS-CoV-2 infection:
- No dose,
- Any recent dose (1-6 months),
- Last dose in >6 months.
1,765 patients with cancer who were then diagnosed with COVID-19 disease between April 2021 and July 2023 (57% female, 68% non-Hispanic White, and 51% age <65 years) were included. 377 (21.4%) had a B-cell hematologic malignancy.
Results:
For all cancer patients, the 6-month overall survival (OS) was 90% among patients who had vaccine within 1-6 months before infection, compared with 82% for patients who had not been vaccinated and those who had vaccination more than 6 months before infection.
Another way of looking at the data was the hazard ratio (HR) or risk of dying. The higher the HR, the higher the risk. The baseline risk is one. Patients with no prior dose of vaccine (HR, 1.50) and those with a last dose in >6 months before infection (HR, 1.39) were associated with an increased likelihood of death as compared with those who received a dose 1-6 months before infection.
For the B-cell cancer patient subgroup that would include the CLL / SLL cohort, we find in the appendix these hazard ratios:
| Subgroup | Hazard Ratio |
| B-cell hematologic malignancy, last dose in 1-6 months | 1.96 (1.17 to 3.29) |
| B-cell hematologic malignancy, no dose | 2.92 (1.74 to 4.92) |
| B-cell hematologic malignancy, last dose in >6 months | 1.84 (1.06 to 3.21) |
Conclusions and Caveats:
While the hazard ratios of dying for CLL / SLL patients were higher than those seen with all the cancer patients, the numbers of patients studied were small, and the absolute mortality rates were better than those seen earlier in the pandemic. Still, one death is one too many deaths. The number of deaths was lowered by vaccination.
One factor to consider is that the study started gathering data in April 2021, which predates the milder Omicron waves.
The study also looked at all-cause mortality after infection over the next 6 months. Being older and more negatively impacted by their cancer (higher ECOG scores) were both significantly associated with higher death rates. It’s possible that not being even partially protected from infection by vaccination was a significant next step on a downhill spiral for those who did succumb from any cause over the following six months.
Interestingly, any vaccination history seemed to offer similar protection to a recent vaccination in the CLL / SLL group, but this, too, might be due to the small numbers involved.
The takeaway is that despite well-documented blunted antibody responses, COVID-19 vaccines provide significant protection to all cancer patients, including those with CLL / SLL.
CLL Society supports individuals with CLL / SLL in working with their healthcare providers to ensure they receive the appropriate vaccinations.
Links:
Read the full JCO Oncology Advances article and appendix with more granular details at: Differential Survival Among Patients With Cancer by COVID-19 Vaccination Status: An Analysis of the ASCO COVID-19 Registry
Stay strong, we are all in this together.
Brian Koffman, MDCM (retired), MS Ed
Co-Founder, Executive VP and Chief Medical Officer
CLL Society
