ABSTRACT
This multicenter observational study included 171 COVID-19 adult patients hospitalized in the ICUs of nine hospitals in Lombardy (Northern Italy) from December, 1st 2021, to February, 9th 2022. During the study period, the Delta/Omicron variant ratio of cases decreased with a delay of two weeks in ICU patients compared to that in the community; a higher proportion of COVID-19 unvaccinated patients was infected by Delta than by Omicron whereas a higher rate of COVID-19 boosted patients was Omicron-infected. A higher number of comorbidities and a higher comorbidity score in ICU critically COVID-19 inpatients was positively associated with the Omicron infection as well in vaccinated individuals. Although people infected by Omicron have a lower risk of severe disease than those infected by Delta variant, the outcome, including the risk of ICU admission and the need for mechanical ventilation due to infection by Omicron versus Delta, remains uncertain. The continuous monitoring of the circulating SARS-CoV-2 variants remains a milestone to counteract this pandemic.
Subject(s)
COVID-19 , SARS-CoV-2 , Adult , Humans , COVID-19/epidemiology , Inpatients , Intensive Care Units , Italy/epidemiologyABSTRACT
Hematological patients at higher risk of severe COVID‐19 were excluded from the severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) vaccine trials. In this single‐center observational prospective study (NCT05074706), we evaluate immune response in the hematological patients followed at the Hematological Division of San Gerardo Hospital, Monza (Italy) deemed to be severely immunosuppressed after vaccination with two doses of the BNT162b2 vaccine. Anti‐SARS‐CoV‐2 immunoglobulin G titers above the cutoff value of 33.8 BAU/ml were detected in 303 (80.2%) out of the 378 patients enrolled. Patients with lymphoproliferative disorders had a significant lower probability of immunization (43.2% vs. 88.4%, p < 0.001). Patients treated with anti‐CD20 showed a significantly lower probability of immunization compared to all other treatments (21.4%, p < 0.0001). Among 69 patients who failed seroconversion, 15 patients (22.7%) showed a positive T‐cell response. Patients previously treated with anti‐CD20 were 2.4 times more likely to test positive for T‐cell responses (p = 0.014). Within a follow‐up of 9 months from the second COVID‐19 vaccination, symptomatic SARS‐CoV‐2 infections were reported by 20 patients (5.3%) and four of them required hospitalization. Successful serological or T‐cell‐mediated immunization conferred protection from symptomatic COVID‐19. Patients treated with anti‐CD20 who were not seroconverted after vaccination might still be protected from COVID‐19 due to the T‐cell immune response.