for the National COVID Cohort Collaborative (N3C) Consortium IMPORTANCE Persons with immune dysfunction have a higher risk for severe COVID-19 outcomes. However, these patients were largely excluded from SARS-CoV-2 vaccine clinical trials, creating a large evidence gap.OBJECTIVE To identify the incidence rate and incidence rate ratio (IRR) for COVID-19 breakthrough infection after SARS-CoV-2 vaccination among persons with or without immune dysfunction. DESIGN, SETTING, AND PARTICIPANTSThis retrospective cohort study analyzed data from the National COVID Cohort Collaborative (N3C), a partnership that developed a secure, centralized electronic medical record-based repository of COVID-19 clinical data from academic medical centers across the US. Persons who received at least 1 dose of a SARS-CoV-2 vaccine between December 10, 2020, and September 16, 2021, were included in the sample.MAIN OUTCOMES AND MEASURES Vaccination, COVID-19 diagnosis, immune dysfunction diagnoses (ie, HIV infection, multiple sclerosis, rheumatoid arthritis, solid organ transplant, and bone marrow transplantation), other comorbid conditions, and demographic data were accessed through the N3C Data Enclave. Breakthrough infection was defined as a COVID-19 infection that was contracted on or after the 14th day of vaccination, and the risk after full or partial vaccination was assessed for patients with or without immune dysfunction using Poisson regression with robust SEs. Poisson regression models were controlled for a study period (before or after [pre-or post-Delta variant] June 20, 2021), full vaccination status, COVID-19 infection before vaccination, demographic characteristics, geographic location, and comorbidity burden.RESULTS A total of 664 722 patients in the N3C sample were included. These patients had a median (IQR) age of 51 (34-66) years and were predominantly women (n = 378 307 [56.9%]). Overall, the incidence rate for COVID-19 breakthrough infection was 5.0 per 1000 person-months among fully vaccinated persons but was higher after the Delta variant became the dominant SARS-CoV-2 strain (incidence rate before vs after June 20, 2021, 2.2 [95% CI, 2.2-2.2] vs 7.3 [95% CI,] per 1000 person-months). Compared with partial vaccination, full vaccination was associated with a 28% reduced risk for breakthrough infection (adjusted IRR [AIRR], 0.72; 95% CI, 0.68-0.76). People with a breakthrough infection after full vaccination were more likely to be older and women. People with HIV infection (AIRR, 1.33; 95% CI, 1.18-1.49), rheumatoid arthritis (AIRR, 1.20; 95% CI, 1.09-1.32), and solid organ transplant (AIRR, 2.16; 95% CI, 1.96-2.38) had a higher rate of breakthrough infection.CONCLUSIONS AND RELEVANCE This cohort study found that full vaccination was associated with reduced risk of COVID-19 breakthrough infection, regardless of the immune status of patients. Despite full vaccination, persons with immune dysfunction had substantially higher risk for COVID-19 breakthrough infection than those without such a condition. For persons with immune...

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Anecdotal clinical observation suggests that rates of chemosensory dysfunction associated with COVID-19 infection may be decreasing. To investigate, the National COVID Cohort Collaborative database was queried for all patients with and without smell and taste loss within 2 weeks of COVID-19 diagnosis. Six-week periods of peak variant prevalence were selected by using CoVariants.org for analysis. Of 3,678,214 patients with COVID-19 in the database, 616,318 met inclusion criteria during the time intervals of interest, with 3431 having an associated smell or taste disturbance diagnosis. With the initial/untyped variant set as the baseline, the odds ratios for alpha, delta, and omicron (December 27, 2021–February 7, 2022) were 0.50 (95% CI, 0.45-0.55; P < .0001), 0.44 (95% CI, 0.41-0.48; P < .0001), and 0.17 (95% CI, 0.15-0.18; P < .0001), respectively. These data strongly support the clinical observation that patients infected with more recent variants are at a significantly lower risk of developing associated chemosensory loss.

Clinical outcomes in solid organ transplant (SOT) recipients with breakthrough COVID (BTCo) after two doses of mRNA vaccination compared to the non‐immunocompromised/immunosuppressed (ISC) general population, are not well described. In a cohort of adult patients testing positive for COVID‐19 between December 10, 2020 and April 4, 2022, we compared the cumulative incidence of BTCo in a non‐ISC population to SOT recipients (overall and by organ type) using the National COVID Cohort Collaborative (N3C) including data from 36 sites across the United States. We assessed the risk of complications post‐BTCo in vaccinated SOT recipients versus SOT with unconfirmed vaccination status (UVS) using multivariable Cox proportional hazards and logistic regression. BTCo occurred in 4776 vaccinated SOT recipients over a median of 149 days (IQR 99–233), with the highest cumulative incidence in heart recipients. The relative risk of BTCo was greatest in SOT recipients (relative to non‐ISC) during the pre‐Delta period (HR 2.35, 95% CI 1.80–3.08). The greatest relative benefit with vaccination for both non‐ISC and SOT cohorts was in BTCo mortality (HR 0.37, 95% CI 0.36–0.39 for non‐ISC; HR 0.67, 95% 0.57–0.78 for SOT relative to UVS). While the relative benefit of vaccine was less in SOT than non‐ISC, SOT patients still exhibited significant benefit with vaccination.