ABSTRACT
Background: Immunogenicity and safety of SARS-CoV-2 vaccines have been widely investigated in patients (pts) with cancer. However, their effectiveness against Coronavirus disease 2019 (COVID-19) and the additional protective effect of a booster dose in this population are yet to be defined. Methods: Using OnCovid study data (NCT04393974), a European registry enrolling consecutive pts with cancer and COVID-19, we evaluated morbidity and 14 days case fatality rates (CFR14) from COVID-19 in pts who were unvaccinated, vaccinated (either partially/full vaccinated but not boosted) and those who had received a third dose. Analyses were restricted to pts diagnosed between 17/11/2021 (first breakthrough infection in a boosted pt) and the 31/01/2022. Pts with unknown vaccination status were excluded. Results: By the data lock of 22/02/2022, out of 3820 consecutive pts from 36 institutions, 415 pts from 3 countries (UK, Spain, Italy) were eligible for analysis. Among them, 51 (12.3%) were unvaccinated, 178 (42.9%) were vaccinated and 186 (44.8%) were boosted. Among vaccinated pts, 26 (14.6%) were partially vaccinated (1 dose). Pts with haematological malignancies had more likely received a booster dose prior to infection (25.4% vs 13.6% and 11.8%, p = 0.02). We found no other associations between vaccination status and pts' characteristics including sex, age, comorbidities, smoking history, tumour stage, tumour status and receipt of systemic anticancer therapy. Compared to unvaccinated pts, boosted and vaccinated pts achieved improved CFR14 (6.8% and 7.0% vs 22.4%, p = 0.01), COVID-19-related hospitalization rates (26.1% and 20.6% vs 41.2%, p = 0.01) and COVID-19-related complications rates (14.5% and 15.7% vs 31.4%). Using multivariable Inverse Probability of Treatment Weighting (IPTW) models adjusted for sex, comorbidities, tumour status and country of origin we confirmed that boosted (OR 0.21, 95%CI: 0.05-0.89) and vaccinated pts (OR 0.19, 95%CI: 0.04-0.81) achieved improved CFR14 compared to unvaccinated pts, whilst a significantly reduced risk of COVID-19 complications (OR 0.26, 95%CI: 0.07-0.93) was reported for vaccinated pts only. Conclusions: SARS-CoV-2 vaccines protect from COVID-19 morbidity and mortality in pts with cancer. Accounting for the enrichment of haematologic pts in the boosted group, the observation of comparable mortality outcomes between boosted and vaccinated pts is reassuring and suggests boosting to be associated with reduced mortality in more vulnerable subjects, despite evidence of adverse features in this group.
ABSTRACT
Background: Whilst patients (pts) with cancer are at increased risk of adverse outcome from Coronavirus disease 2019 (COVID-19), no evidence exists as to the natural history of the SARS-CoV-2 B.1.1.529 (Omicron) variant in this population. Methods: Capitalizing on OnCovid study data (NCT04393974), a European registry that collects data on consecutive patients with cancer and COVID-19, we analysed COVID-19 morbidity and case fatality rates at 14 days (CFR14) across 3 phases defined following the evolution of the pandemic in Europe, according to date of COVID-19 diagnosis: “Pre-vaccination” phase (27/02/2020-30/ 11/2020), “Alpha-Delta variant” phase (01/12/2020-14/12/2021), “Omicron variant” phase (15/12/2020-31/01/2022). Results: By the data lock of 04/02/2022, 3820 consecutive pts were enrolled, 3473 of whom were eligible for this analysis. Among them, 2033 (58.6%), 1075 (30.9%) and 365 (10.5%) were diagnosed during the Pre-vaccination, Alpha-Delta and Omicron phases. Pts diagnosed in the Omicron phase were more likely aged < 65 years (48.6% vs 42.5%, 39.4% p = 0.01), had < 2 comorbidities (61.9% vs 55.6%, 52.1% p = 0.01). They had more advanced-stage tumours (62.1% vs 53.3%, 49.0%, p < 0.01) and were more likely receiving systemic anticancer therapy (SACT) at COVID-19 diagnosis (54.9% vs 43.9%, 39.6%, p < 0.01). Proportions of fully vaccinated/boosted pts were higher in the Omicron phase (33.9%-48.1%) compared to the Alpha-Delta phase (16.6%-2.3%, p < 0.01). Pts diagnosed in the Omicron phase had improved CFR14 (9.0% vs 13.9%, 23.1%, p < 0.01) lower hospitalization rates due to COVID-19 (24.4% vs 41.4%, 56.6%, p < 0.01), lower complications rates (15.3% vs 33.6%, 39.4%, p < 0.01) and reduced need for COVID-19 specific therapy (22.4% vs 43.0%, 65.7% p < 0.01) compared to the Alpha-Delta and pre-vaccinal phase. After adjusting for country of origin, sex, age, comorbidities, tumour stage, status and receipt of SACT at COVID-19, patients diagnosed in the Omicron phase displayed the lowest risk of death at 14 days compared to earlier phases. Similarly, rates of hospitalization and complicated COVID-19 were lowest for Omicron phase. Conclusions: This is the first study to portray the evolution of the SARS-CoV-2 Omicron outbreak in Europe, documenting an improvement in all COVID-19 outcomes compared to earlier phases of the pandemic. Enhanced healthcare capacity, improved disease management, immunization campaigns alongside differential virulence of viral strains are likely contributing to improved outcomes across phases.