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medrxiv; 2022.
Preprint Dans Anglais | medRxiv | ID: ppzbmed-10.1101.2022.01.15.22269360


Background We estimated vaccine effectiveness (VE) of mRNA vaccines among US Veterans during periods of Delta and Omicron variant dominance. Patients included in this study were largely 65 years or older (62,834, 55%), male (101,259, 88%), and non-Hispanic white (66,986, 58%). Methods We used SARS-CoV-2 laboratory test results to conduct a matched test-negative case-control study to estimate VE of three and two doses of mRNA vaccines against infection (regardless of symptoms), and a matched case-control study to estimate VE against COVID-19-related hospitalization and death. We estimated VE as (1-odds ratio) x 100%. Severity of disease was measured using hospital length of stay (LOS) and admission to an intensive care unit (ICU). Results Against infection, booster doses had 7-times higher VE - 59% (95% confidence interval [CI], 57 to 61) - than 2-dose VE (7%; 95% CI, 3 to 10) during the Omicron period. For the Delta period, estimated VE against infection was 90% (95% CI, 88 to 92) among boosted vaccinees, 64% higher than VE among 2-dose vaccinees [55% (95% CI, 51 to 58)]. Against hospitalization, booster dose VE was 87% (95% CI, 80 to 91) during Omicron and 95% (95% CI, 91 to 97) during Delta; the 2-dose VE was 44% (95% CI, 26 to 58) during Omicron and 75% (95% CI, 70 to 80) during Delta. Against death, estimated VE with a booster dose was 94% (95% CI, 85 to 98) during Omicron and 96% (95% CI, 88 to 99) during Delta, while the 2-dose VE was 75% (95% CI, 52 to 87) during Omicron and 93% (95% CI, 85 to 97) during Delta. During the Omicron period, average hospital LOS was 4 days shorter [3 days (95%CI, 3 to 4 days)] than during the Delta period. Conclusions A mRNA vaccine booster is more effective against infection, hospitalization, and death than 2-dose vaccination among an older male population with comorbidities.

medrxiv; 2021.
Preprint Dans Anglais | medRxiv | ID: ppzbmed-10.1101.2021.07.06.21259982


Objectives: To determine whether early oral or parenteral corticosteroids compared to no corticosteroids are associated with decreased mortality in patients hospitalized with coronavirus disease 2019 (COVID-19) who are not on intensive respiratory support (IRS) within 48 hours of admission. Design: Observational cohort study Setting: Nationwide cohort of patients receiving care in the Department of Veterans Affairs, a large integrated US national healthcare system Participants: 9,058 patients admitted to a Veterans Affairs Medical Center between June 7, 2020-December 5, 2020 within 14-days after SARS-CoV-2 positive test; exclusion criteria include less than a 48 hour stay, receipt of prior systemic corticosteroids, and no indication of acute medical care for COVID-19. Main outcome measure: 90-day all-cause mortality Results: Of 9,058 total patients (95% men, median age 71 years, 27% black), 6,825 (75%) were not on IRS within 48 hours. Among the 3,025 patients on no oxygen, 598 (20%) received corticosteroids and 283 (9%) died; of 3,800 patients on low-flow nasal cannula oxygen (NC), 2,808 (74%) received corticosteroids and 514 (13%) died. In stratified, inverse probability weighted Cox proportional hazards models comparing those who did and did not receive corticosteroids, patients on no oxygen experienced an 89% increased risk for 90-day mortality (hazard ratio [HR] 1.89, 95% confidence interval [CI] 1.33 to 2.68); there was weak evidence of increased mortality among patients on NC (HR 1.21, 95% CI 0.94 to 1.57). Results were robust in subgroup analyses including restricting corticosteroids to dexamethasone, and in sensitivity analyses employing different modeling approaches. Conclusions: In patients hospitalized with COVID-19, we found no evidence of a mortality benefit associated with early initiation of corticosteroids among those on no oxygen or NC in the first 48 hours, though there was evidence of potential harm. These real-world findings support that clinicians should consider withholding corticosteroids in these populations and further clinical trials may be warranted.

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