Background: The availability of safe and effective COVID-19 vaccines has enabled protections against serious outcomes from SARS-CoV-2 infection. The ASCO Registry provides an opportunity to study the rate of vaccine uptake among patients (pts) with cancer who had SARS-CoV-2 infection prior to availability of vaccines. Methods: Participating US medical oncology practices identify pts eligible for inclusion: pts with a positive SARS-CoV-2 test and, at the same time, either (a) or (b) cancer-free less than 12 months (i.e., in complete remission or post-resection) and receiving adjuvant treatment. Registry data were extracted on 2/4/22. Pts in this analysis had a SARS-CoV-2 positive test between 3/1/2020 and 12/31/2020 and at least one clinical encounter on or after 1/1/21, documenting receipt or not of 1^st and 2^nd vaccine shots. Pts lacking data on vaccination status in their medical records were excluded from analysis. When the exact date of 1^st vaccine shot was known, the primary endpoint was number of days from 1/1/21 to 1^st shot date. If the exact date of 1^st shot was unknown, date was categorized as within 7 days from the clinical encounter, 2-4 weeks, or more than 1 month prior. Summary statistics and 95% confidence intervals (CIs) were calculated using Kaplan-Meier methods. Results: The Registry included 1260 pts with SARS-CoV-2 infection in 2020. Time to vaccination (described using cumulative incidence) across age categories is shown in Table, with 1/1/21 as the baseline. Median time to vaccination ranged from 63 days in the oldest pts (> 80 years of age) to 220 days in the youngest pts (< 45 years of age). Differences in rates of vaccination uptake were most pronounced in the early months (Jan – Mar) and diminished in April and beyond. Conclusions: Older pts with cancer who were infected with SARS-CoV-2 in 2020 received COVID-19 vaccinations in 2021 at higher rates than those of younger ages. Delayed uptake by younger aged pts at outset could be related to lack of clarity on pts with cancer qualifying for early vaccine access and state policies on availability.

¹ Estimated date at which 50% of the pts had received 1^st vaccination Vax = vaccination