1600P Suboptimal response to COVID-19 mRNA vaccines in older patients with cancer


      SARS-CoV-2mRNA vaccines were approved to prevent COVID-19 infection, with reported vaccine efficacy of 95%. Older patients with cancer are at risk for lower vaccine immunogenicity and were not included in the registration trials. We assessed vaccine immunogenicity in this special population.


      We recruited elderly vaccinated patients from the René Muret hospital between Apr 5, 2021 and May 8, 2021. All were inpatients in a 48-bed geriatric rehabilitation ward, where a cluster of B.1.1.7 (VOC-202012/1) variant COVID-19 cases occurred. We measured SARS-CoV-2 IgG production in all patients. We observed patients who developed symptomatic SARS-CoV-2 infection (confirmed by RT-PCR) despite previous vaccination with mRNA vaccine.


      Thirty vaccinated patients were enrolled. Mean age was 83 years and 60% were female. The IgG S-protein serology was positive in 16 of 18 (89%) patients without cancer. Immunogenicity among patients with cancer was significantly lower with positive serology in only 7 of 12 (58%, p<0.001). Antibody level was also significantly lower in this group (mean 2946 AU/mL vs. 4447 AU/mL in controls, p<0.001). Severe SARS-CoV-2 infection occurred in 7 patients included 5 with cancer. Predictors for infection among older patients were: negative serology, haematological cancer (CLL or NHL), lung cancer, and treatment with high dose steroids. Covid-19 related deaths occurred in 5 patients included 4 with cancer.


      Routine measurement of post-vaccine antibodies in older patients with cancer should be considered. Novel strategies are needed to prevent COVID-19 in these individuals.

      Legal entity responsible for the study

      T. Landre.


      Has not received any funding.


      All authors have declared no conflicts of interest.