Comparative COVID-19 Vaccine Effectiveness Over Time in Veterans.

Background: Comparative effectiveness of coronavirus disease 2019 (COVID-19) vaccines across patient subgroups is poorly understood and essential to precisely targeting vaccination strategies. Methods: We used the US Department of Veterans Affairs COVID-19 Shared Data Resource to identify veterans who utilize VA health care and had no documented severe acute respiratory syndrome coronavirus 2 infection before December 11, 2020. Using a test-negative case-control design (TND), we used conditional logistic regression with adjustment for covariates to estimate vaccine effectiveness (VE) over time for veterans who received 2 doses of mRNA vaccines or 1 dose of Ad26.Cov2.S. Results: We identified 4.8 million veterans with a mean age of 64 years, of whom 58% had ≥1 chronic disease. Vaccine effectiveness for symptomatic infections, hospitalizations, and ICU admission or death declined over time and varied by the type of vaccine (P < 0.01). VE estimates against symptomatic infection during months 1 and 7 for mRNA-1273 compared with BNT162b2 were 89.7% (95% CI, 84.4%-93.0%) and 57.3% (95% CI, 48.4%-64.7%) vs 81.6% (95% CI, 75.9%-85.9%) and 22.5% (95% CI, 7.2%-35.2%) for individuals age <65 years and 78.4% (95% CI, 71.1%-83.9%) and 36.2% (95% CI, 27.7%-43.6%) vs 66.3% (95% CI, 55.7%-74.4%) and -23.3% (95% CI, -40.5% to -8.2%) in subjects age ≥65 years; against hospitalization 92.0% (95% CI, 76.1%-97.3%) and 83.1% (95% CI, 66.8%-91.4%) vs 85.6% (95% CI, 72.6%-92.4%) and 57.0% (95% CI, 31.2%-73.2%) in subjects age <65 years and 66.1% (95% CI, 45.3%-79.0%) and 64.7% (95% CI, 55.2%-72.3%) vs 61.0% (95% CI, 41.3%-74.2%) and 1.7% (95% CI, -22.0% to 20.8%) in those age ≥65 years; against ICU admission or death 89.2% (95% CI, 49.5%-97.7%) and 84.4% (95% CI, 59.0%-94.1%) vs 87.6% (95% CI, 61.0%-96.1%) and 66.4% (95% CI, 7.7%-87.8%) in subjects age <65 years and 75.4% (95% CI, 51.7%-87.5%) and 73.8 (95% CI, 62.9%-81.5%) vs 67.4% (95% CI, 32.6%-84.3%) and 29.3% (95% CI, 2.3%-48.9%) in subjects age ≥65 years, respectively (P interaction < .01 for all comparisons). Similarly, mRNA-1273 was more effective than BNT162b2 in veterans with >1 chronic disease. Conclusions: mRNA-1273 was more effective than BNT162b2 in older veterans and those with chronic diseases.

Relative Vaccine Effectiveness of a SARS-CoV-2 mRNA Vaccine Booster Dose Against the Omicron Variant.

BACKGROUND: The current SARS-CoV-2 vaccines may be less effective against the Omicron variant. With recent resurgence of SARS-CoV-2 cases, the role of booster doses of the vaccine needs to be highlighted. METHODS: Using a retrospective cohort study design emulating a target trial, we determined the relative effectiveness of a homologous booster dose of a SARS-CoV-2 mRNA vaccine compared with primary series alone in preventing infection, hospitalization, and intensive care unit (ICU) admission, and death in the Department of Veterans Affairs healthcare system in the US. Among infection-free survivors who received two doses of an mRNA vaccine prior to April 30, 2021, we identified those who received a booster between September 22 and December 25, 2021 and 1:1 matched individuals who did not receive a booster. RESULTS: Among 2,384,272 previously uninfected persons with two doses of an mRNA vaccine by April 30, 2021, we identified 462,950 booster recipients between September 22 and December 25, 2021 who were matched 1:1 with non-booster recipients. RVE (95% CI) was 19% (17-22%) for confirmed infection, 52% (46-57%) for hospitalization, and 83% (65-92%) for ICU admission or death. Recipients of the mRNA-1273 vaccine had a lower cumulative incidence of infections and hospitalizations compared with BNT-162b2 vaccine (log-rank p-value <0.001 for both comparisons). CONCLUSION: While the RVE of SARS-CoV-2 mRNA booster vaccine dose in preventing infection against the Omicron variant is low, the RVE is substantial in preventing hospitalization and high in preventing the most severe/critical disease.

Variation in Clinical Treatment and Outcomes by Race Among US Veterans Hospitalized With COVID-19.

Importance: Patients from racially and ethnically minoritized populations, such as Black and Hispanic patients, may be less likely to receive evidence-based COVID-19 treatments than White patients, contributing to adverse clinical outcomes. Objective: To determine whether clinical treatments and outcomes among patients hospitalized with COVID-19 were associated with race. Design, Setting, and Participants: This retrospective cohort study was conducted in 130 Department of Veterans Affairs Medical Centers (VAMCs) between March 1, 2020, and February 28, 2022, with a 60-day follow-up period until May 1, 2022. Participants included veterans hospitalized with COVID-19. Data were analyzed from May 6 to June 2, 2022. Exposures: Self-reported race. Main Outcomes and Measures: Clinical care processes (eg, intensive care unit [ICU] admission; organ support measures, including invasive and noninvasive mechanical ventilation; prone position therapy, and COVID-19-specific medical treatments) were quantified. Clinical outcomes of interest included in-hospital mortality, 60-day mortality, and 30-day readmissions. Outcomes were assessed with multivariable random effects logistic regression models to estimate the association of race with outcomes not attributable to known mediators, such as socioeconomic status and age, while adjusting for potential confounding between outcomes and mediators. Results: A total of 43 222 veterans (12 135 Black veterans [28.1%]; 31 087 White veterans [71.9%]; 40 717 [94.2%] men) with a median (IQR) age of 71 (62-77) years who were hospitalized with SARS-CoV-2 infection were included. Controlling for site of treatment, Black patients were equally likely to be admitted to the ICU (4806 Black patients [39.6%] vs 13 427 White patients [43.2%]; within-center adjusted odds ratio [aOR], 0.95; 95% CI, 0.88-1.02; P = .17). Two-thirds of patients treated with supplemental oxygen or noninvasive or invasive mechanical ventilation also received systemic steroids, but Black veterans were less likely to receive steroids (within-center aOR, 0.88; 95% CI, 0.80-0.96; P = .004; between-center aOR, 0.67; 95% CI, 0.48-0.96; P = .03). Similarly, Black patients were less likely to receive remdesivir (within-center aOR, 0.89; 95% CI, 0.83-0.95; P < .001; between-center aOR, 0.68; 95% CI, 0.47-0.99; P = .02) or treatment with immunomodulatory drugs (within-center aOR, 0.77; 95% CI, 0.67-0.87; P < .001). After adjusting for patient demographic characteristics, chronic health conditions, severity of acute illness, and receipt of COVID-19-specific treatments, there was no association of Black race with hospital mortality (within-center aOR, 0.98; 95% CI, 0.86-1.10; P = .71) or 30-day readmission (within-center aOR, 0.95; 95% CI, 0.88-1.04; P = .28). Conclusions and Relevance: These findings suggest that Black veterans hospitalized with COVID-19 were less likely to be treated with evidence-based COVID-19 treatments, including systemic steroids, remdesivir, and immunomodulatory drugs.

Real-World Effectiveness of the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) mRNA Vaccines in Preventing Confirmed Infection in Patients on Chronic Hemodialysis.

BACKGROUND: Persons on chronic hemodialysis have a significantly diminished humoral immune response to SARS-CoV-2 vaccines. Whether this translates to reduced vaccine effectiveness (VE) is unknown. METHODS: We used the US Department of Veterans Affairs COVID-19 Shared Data Resource to identify all veterans who were tested for SARS-CoV-2 between 26 January and 31 August 2021. Using International Classification of Diseases, 10th edition, codes and attendance at a dialysis clinic/center, we identified those who were on chronic hemodialysis. We used a test-negative, case-control design using a doubly robust logistic regression model to determine the VE of the BNT-162b2 (Pfizer) or mRNA-1273 (Moderna) vaccines in preventing confirmed SARS-CoV-2 infection. RESULTS: Among 847 199 veterans tested for SARS-CoV-2 between 26 January and 31 August 2021, there were 6076 veterans on chronic hemodialysis. Among those, we identified 1270 cases (580 fully vaccinated) and 2959 controls (2120 fully vaccinated). The overall VE >14 days after the second dose in preventing documented infection was 68.2% (95% CI: 62.6-72.9%). VE was 68.9% (95% CI: 61.9-74.7%) for Pfizer BNT-162b2 and 66.7% (95% CI: 58.9-73.0%) for Moderna mRNA-1273 vaccine. There was no difference in VE by age (<70 vs >70 years), race, or sex. There were no events recorded in persons with a Charlson's comorbidity index score <2. CONCLUSIONS: VE of 2 doses of current mRNA vaccines in preventing SARS-CoV-2 infection in persons on chronic hemodialysis is lower than historic VE rates in the general population. Effects of additional doses in improving VE in this special population need further study.

Comparative COVID-19 Vaccine Effectiveness over Time in Veterans

Background Comparative effectiveness of COVID-19 vaccines across patient subgroups is poorly understood and essential to precisely target vaccination strategies. Methods We used the US Department of Veterans Affairs COVID-19 Shared Data Resource to identify veterans who utilize VA healthcare and had no documented SARS-CoV-2 infection before December 11, 2020. Using a test-negative case-control design (TND), we used conditional logistic regression with adjustment for covariates to estimate vaccine effectiveness (VE) over time for Veterans who received two doses of mRNA vaccines or one dose of Ad26.Cov2.S. Results We identified 4.8 million veterans with a mean age of 64 years, of whom 58% had at least one chronic disease. Vaccine effectiveness for symptomatic infections, hospitalizations, and ICU admission or death declined over time and varied by the type of vaccine (P < 0.01). VE estimates against symptomatic infection during months 1 and 7 for mRNA-1273 compared to BNT162b2 were 89.7% (CI 84.4-93.0) and 57.3% (CI 48.4-64.7) vs. 81.6% (CI 75.9-85.9) and 22.5% (CI 7.2-35.2) for individuals <65 years and 78.4% (CI: 71.1-83.9) and 36.2% (CI 27.7-43.6) vs. 66.3% (CI 55.7-74.4) and -23.3% (CI -40.5, -8.2) in subjects ≥ 65 years;Against hospitalization 92.0% (76.1-97.3) and 83.1% (CI 66.8-91.4) vs. 85.6% (CI 72.6-92.4) and 57.0% (CI 31.2-73.2) in subjects <65 years, and 66.1%(CI 45.3-79.0) and 64.7%(CI 55.2-72.3) vs. 61.0% (CI 41.3-74.2) and 1.7% (CI -22.0-20.8) in those ≥65 years;Against ICU admission or death in subjects < 65 years of age 89.2% (CI 49.5-97.7) and 84.4% (CI 59.0-94.1). vs. 87.6% (CI 61.0-96.1) and 66.4% (CI 7.7-87.8), and 75.4% (CI 51.7-87.5) and 73.8 (CI 62.9-81.5) vs. 67.4% (CI 32.6-84.3) and 29.3% (CI 2.3-48.9) in subjects ≥65 years of age, respectively (interaction P < 0.01 for all comparisons). Similarly, mRNA-1273 was more effective than BNT162b2 in veterans with more than one chronic disease. Conclusions mRNA-1273 was more effective than BNT162b2 in older veterans and those with chronic diseases.

COVID-19 disease severity in US Veterans infected during Omicron and Delta variant predominant periods.

The SARS-CoV-2 Omicron variant is thought to cause less severe disease among the general population, but disease severity among at-risk populations is unknown. We performed a retrospective analysis using a matched cohort of United States veterans to compare the disease severity of subjects infected during Omicron and Delta predominant periods within 14 days of initial diagnosis. We identified 22,841 matched pairs for both periods. During the Omicron period, 20,681 (90.5%) veterans had mild, 1308 (5.7%) moderate, and 852 (3.7%) severe disease. During the Delta predominant period, 19,356 (84.7%) had mild, 1467 (6.4%) moderate, and 2018 (8.8%) severe disease. Moderate or severe disease was less likely during the Omicron period and more common among older subjects and those with more comorbidities. Here we show that infection with the Omicron variant is associated with less severe disease than the Delta variant in a high-risk older veteran population, and vaccinations provide protection against severe or critical disease.

Vaccine Effectiveness of 3 Versus 2 Doses of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) mRNA Vaccines in a High-Risk National Population.

BACKGROUND: Knowledge of the vaccine effectiveness (VE) of a third or booster vaccine dose in preventing SARS-CoV-2 infection or its consequences is critical in developing recommendations for their use. We determined relative VE of 3 vs 2 doses of an mRNA vaccine in preventing symptomatic SARS-CoV-2 infection, hospitalization, and severe/critical disease. METHODS: Among veterans who had received 2 doses of an mRNA vaccine by 30 April 2021, we identified those who received a third dose of the same vaccine between 22 September and 24 November 2021 and 1:1 matched controls who had not received their third dose by then. Using Cox proportional hazards model, we calculated adjusted hazards ratios for symptomatic infection, hospitalization, and intensive care unit (ICU) admission or death after SARS-CoV-2-positive test. RESULTS: Among 2 321 366 veterans who received 2 doses of Pfizer BNT-162b2 or Moderna mRNA-1273 vaccine by 30 April 2021, we matched 395 686 persons who received a third dose of the same vaccine between 22 September and 24 November 2021 to controls who did not receive a third dose. Adjusted HRs (95% CI) were .15 (.11-.21) for symptomatic infection and .18 (.13-.26) for hospitalizations for 3 vs 2 doses, corresponding to relative VE of 85% and 82%. Five ICU admissions or deaths were observed (4 among recipients of 2 doses). There was no difference in VE between BNT162b2 versus mRNA-1273 recipients. CONCLUSIONS: A third dose of a SARS-CoV-2 mRNA vaccine is associated with high VE against symptomatic infection, hospitalization, and critical disease in the pre-Omicron era.