COVID-19 vaccination may reduce the risk of COVID-19 sequelae in patients with cancer, researchers reported in The Lancet Oncology.

An analysis of data from 2020 to early 2022 showed that cancer patients who received 2 vaccine doses and those who received a booster dose had a significantly lower prevalence of COVID-19 sequelae than unvaccinated or partially vaccinated patients.

However, vaccinated and unvaccinated patients had a similar incidence of COVID-19 sequelae during the alpha-delta phase of the pandemic and during the omicron phase. 

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This study included 1909 cancer patients who were diagnosed with COVID-19 and enrolled in the OnCovid registry. Roughly half of patients (55%) had active cancer. The most common cancer types were gastrointestinal, gynecologic or genitourinary, hematologic, thoracic, and breast cancers. 

About half of patients (52.4%) were diagnosed with COVID-19 before vaccines were available (February 27, 2020, to November 30, 2020). Roughly one-third (34.2%) were diagnosed during the alpha-delta phase of the pandemic (December 1, 2020, to December 14, 2021), and 13.4% were diagnosed during the omicron phase (December 15, 2021, to January 31, 2022). 

Overall, 16.6% of patients had at least 1 sequela from COVID-19 at the first oncological reassessment, which took place a median of 39 days from COVID-19 diagnosis. Patients had respiratory sequelae (9.0%), prolonged fatigue (7.0%), neurocognitive sequelae (2.9%), weight loss (1.6%), and other categories of organ dysfunction (1.3%). 

When the researchers evaluated patients by vaccination status and time period, there was no significant difference in the proportion of patients with COVID-19 sequelae by vaccination status. 

During the alpha-delta phase, 13.0% of vaccinated patients had COVID-19 sequelae, as did 18.3% of unvaccinated patients. (P =0.16). During the omicron phase, 6.1% of vaccinated patients and 9.4% of unvaccinated patients had COVID-19 sequelae (P =.49).

However, in a univariable analysis across all time periods, patients who received a booster and those who received 2 vaccine doses had a significantly lower prevalence of COVID-19 sequelae than patients who were unvaccinated or partially vaccinated.

The prevalence of COVID-19 sequelae was 7.4% in the booster group, 9.8% in the 2-dose group, and 18.5% in the unvaccinated/partially vaccinated group (P =.0001). The prevalence of respiratory sequelae was 4.4%, 6.0%, and 9.9%, respectively (P =.030). The prevalence of prolonged fatigue was 2.2%, 5.4%, and 7.7%, respectively (P =.037). There were no significant differences for other sequelae.

In an inverse probability of treatment weighting analysis, vaccinated patients had a lower risk of COVID-19 sequelae (odds ratio [OR], 0.41; 95% CI, 0.24-0.69), respiratory sequelae (OR, 0.52; 95% CI, 0.29-0.95), and prolonged fatigue (OR, 0.49; 95% CI, 0.25-0.97).

The median post-COVID-19 follow-up was 12.6 months. Patients with any COVID-19 sequelae had an increased risk of death compared with patients who did not have any COVID-19 sequelae (hazard ratio [HR], 1.61; 95% CI, 1.28-2.01). A multivariable analysis also showed an increased risk of death among patients with COVID-19 sequelae (HR, 1.39; 95% CI, 1.10-1.74). 

“To our knowledge, this study is the first to confirm that previous vaccination is independently associated with improved COVID-19 outcomes even during the post-acute phase of the disease, despite the presumed lower pathogenicity of the omicron variant,” the researchers wrote. “Although we cannot mechanistically prove the protective role of SARS-CoV-2 vaccines against COVID-19 sequelae, the underlying causative link is biologically plausible and represents a potentially practice-informing finding despite possible sources of heterogeneity, including selection and ascertainment bias.”

Disclosures: Some study authors declared affiliations with biotech, pharmaceutical, and/or device companies. Please see the original reference for a full list of disclosures.


Cortellini A, Tabernero J, Mukherjee U, et al. SARS-CoV-2 omicron (B.1.1.529)-related COVID-19 sequelae in vaccinated and unvaccinated patients with cancer: results from the OnCovid registry. Lancet Oncol. Published online March 7, 2023. doi:10.1016/S1470-2045(23)00056-6