Association of COVID-19 Vaccination With Breakthrough Infections and Complications in Patients With Cancer.

Importance: Patients with cancer are known to have increased risk of COVID-19 complications, including death. Objective: To determine the association of COVID-19 vaccination with breakthrough infections and complications in patients with cancer compared to noncancer controls. Design, Setting, and Participants: Retrospective population-based cohort study using linked administrative databases in Ontario, Canada, in residents 18 years and older who received COVID-19 vaccination. Three matched groups were identified (based on age, sex, type of vaccine, date of vaccine): 1:4 match for patients with hematologic and solid cancer to noncancer controls (hematologic and solid cancers separately analyzed), 1:1 match between patients with hematologic and patients with solid cancer. Exposures: Cancer diagnosis. Main Outcomes and Measures: Outcomes occurring 14 days after receipt of second COVID-19 vaccination dose: primary outcome was SARS-CoV-2 breakthrough infection; secondary outcomes were emergency department visit, hospitalization, and death within 4 weeks of SARS-CoV-2 infection (end of follow-up March 31, 2022). Multivariable cumulative incidence function models were used to obtain adjusted hazard ratio (aHR) and 95% CIs. Results: A total of 289 400 vaccinated patients with cancer (39 880 hematologic; 249 520 solid) with 1 157 600 matched noncancer controls were identified; the cohort was 65.4% female, and mean (SD) age was 66 (14.0) years. SARS-CoV-2 breakthrough infection was higher in patients with hematologic cancer (aHR, 1.33; 95% CI, 1.20-1.46; P < .001) but not in patients with solid cancer (aHR, 1.00; 95% CI, 0.96-1.05; P = .87). COVID-19 severe outcomes (composite of hospitalization and death) were significantly higher in patients with cancer compared to patients without cancer (aHR, 1.52; 95% CI, 1.42-1.63; P < .001). Risk of severe outcomes was higher among patients with hematologic cancer (aHR, 2.51; 95% CI, 2.21-2.85; P < .001) than patients with solid cancer (aHR, 1.43; 95% CI, 1.24-1.64; P < .001). Patients receiving active treatment had a further heightened risk for COVID-19 severe outcomes, particularly those who received anti-CD20 therapy. Third vaccination dose was associated with lower infection and COVID-19 complications, except for patients receiving anti-CD20 therapy. Conclusions and Relevance: In this large population-based cohort study, patients with cancer had greater risk of SARS-CoV-2 infection and worse outcomes than patients without cancer, and the risk was highest for patients with hematologic cancer and any patients with cancer receiving active treatment. Triple vaccination was associated with lower risk of poor outcomes.

Factors Associated with Timely COVID-19 Vaccination in a Population-based Cohort of Patients with Cancer.

BACKGROUND: In many jurisdictions, cancer patients were prioritized for COVID-19 vaccination due to increased risk of infection and death. To understand sociodemographic disparities which impacted timely receipt of COVID-19 vaccination amongst cancer patients, we undertook a population-based study in Ontario, Canada. METHODS: Patients >18 years, diagnosed with cancer 01/2010- 09/2020 were identified using administrative data; vaccination administration was captured between approval (12/2020) up to 02/2022. Factors associated with time to vaccination were evaluated using multivariable Cox proportional hazards regression. RESULTS: The cohort consisted of 356,535 patients, majority of whom had solid tumor cancers (85.9%) and were not on active treatment (74.1%); 86.8% had received at least two doses. Rate of vaccination was 25% lower in recent (HR: 0.74,95% CI: 0.72-0.76) and non-recent immigrants (HR: 0.80, 95% CI: 0.79-0.81). A greater proportion of unvaccinated patients were from neighborhoods with high concentration of new immigrants or self-reported members of racialized groups (26.0% vs 21.3%, standardized difference: 0.111, p < 0.01), Residential Instability (27.1% vs 23.0%, standardized difference: 0.094, p < 0.01) or Material Deprivation (22.1% vs 16.8%, standardized difference: 0.134, p < 0.01), and low socioeconomic status (20.9% vs 16.0%, standardized difference: 0.041, p < 0.01). Rate of vaccination was 20% lower in patients from neighborhoods with the lowest socioeconomic status (HR: 0.82, 95% CI: 0.81-0.84) and highest material deprivation (HR: 0.80, 95% CI: 0.78-0.81) relative to those in more advantaged neighborhoods. CONCLUSION: Despite funding of vaccines and prioritization of high-risk populations, marginalized patients were less likely to be vaccinated. Differences are likely due to the interplay between systemic barriers to access, and cultural/ social influences impacting uptake.

Primary care utilization for patients with newly diagnosed cancer during the COVID-19 pandemic: a population-based study.

BACKGROUND: The COVID-19 pandemic greatly impacted primary care and cancer care. We studied how primary care utilization in Ontario, Canada changed for patients who were newly diagnosed with cancer just prior to the COVID-19 pandemic compared to those diagnosed in non-pandemic years. METHODS: This population-based, retrospective cohort study used linked healthcare databases to compare outcomes for patients with a new malignancy diagnosed within the year prior to the COVID-19 pandemic, between July 1 and September 30, 2019 (COVID-19 cohort) to those diagnosed in the same months in 2018 and 2017 (pre-pandemic cohort). We used Poisson regression models to compare rates of in-person and virtual visits to patients' usual primary care physician (PCP), emergency department (ED) visits, and hospitalizations, all reported per person-year of follow-up. RESULTS: In-person visits to usual PCPs decreased from 4.07/person-year in the pre-pandemic cohort to 2.58 in the COVID-19 cohort (p < 0.0001). Virtual visits to usual PCPs increased from 0.00 to 1.53 (p < 0.0001). Combined in-person and virtual visits to patients' usual PCPs was unchanged from 4.07 to 4.12 (p = 0.89). The rate of ED visits decreased from 0.99/person-year to 0.88 (p < 0.0001). Non-elective hospitalizations remained unchanged, from 0.49/person-year to 0.47 (p = 0.1675). CONCLUSION: There was a sizeable shift in primary care visits for cancer patients from in-person to virtual during the pandemic, although there was no resultant increase in hospitalizations. This suggests that early in the pandemic, virtual care allowed for continuity in utilization of primary care, though further studies are required to confirm this persisted later in the pandemic.