key: cord-0691346-dnuitsb5
authors: Zitek, Tony; Jodoin, Kathleen; Kheradia, Tarang; Napolillo, Ryan; Dalley, Michael T.; Quenzer, Faith; Farcy, David A.
title: Vaccinated patients have reduced rates of hospitalization after receiving casirivimab and imdevimab for COVID-19
date: 2021-11-02
journal: Am J Emerg Med
DOI: 10.1016/j.ajem.2021.10.044
sha: aeaa26761e3e4b88e1e67ecdaf75166e7adf5aee
doc_id: 691346
cord_uid: dnuitsb5

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For outpatients with COVID-19, casirivimab/imdevimab (brand name REGEN-COV), a neutralizing monoclonal antibody cocktail, received emergency use authorization in November 2020 and has been widely utilized since [1] . This medication reduces viral load and subsequent hospitalizations [2, 3] . At the same time, adverse effects from this medication are rare [2] [3] [4] .

Therefore, previous data support the use of casirivimab/imdevimab. However, these data do not account for the fact that a large number of patients now receiving casirivimab/imdevimab have been vaccinated against COVID-19. The CDC recommends the use of monoclonal antibody therapies regardless of vaccination status [5], but the benefit is uncertain. Thus, we performed a study to assess the outcomes after casirivimab/imdevimab treatment in vaccinated patients as compared to unvaccinated patients.

Our study was a multi-center, retrospective cohort analysis of patients with COVID-19 who received casirivimab/imdevimab at an ED in our hospital system. Sites included one tertiary care facility and two freestanding EDs. This study received approval by our primary hospital's institutional review board.

All patients who received casirivimab/imdevimab in our ED between December 9, 2020 (the day we began administering this medication) and August 20, 2021 were included. At our facilities, J o u r n a l P r e -p r o o f Journal Pre-proof casirivimab/imdevimab is used for select non-hospitalized patients within 10 days of symptom onset per FDA guidelines [6] .

For each patient, the following data were collected: age, gender, race, ethnicity, body mass index (BMI), and COVID-19 vaccination records. These data were pulled directly from Epic (Madison, WI), and vaccination data were verified on Florida SHOTS (Florida's vaccination records system). Outcome measures (within 28 days of casirivimab/imdevimab treatment) were hospitalizations, return visits to the ED, intensive care unit (ICU) admissions, and deaths.

These were assessed by a combination of medical record review from our facility, review of Epic's Care Everywhere (which allows for a review of medical records from other facilities that use Epic), and phone follow up with patients.

Using these data, we compared patients who were fully vaccinated at the time of casirivimab/imdevimab treatment to those who were unvaccinated. Our primary outcome was the risk of hospitalization within 28 days of treatment as assessed by multivariate logistic regression. Secondarily, we assessed the rates of return visits to the ED, ICU admissions, and deaths within 28 days.

To analyze our data, we compared vaccinated to unvaccinated patients using univariate descriptive statistics and multivariate logistic regression analyses with hospitalizations within 28 days as the dependent variable. Age, gender, race, ethnicity, and BMI were chosen as predictor J o u r n a l P r e -p r o o f Journal Pre-proof variables for the regression model based on consistency of documentation and prior studies demonstrating associations of these variables with worse outcomes form COVID-19 [7] [8] [9] [10] [11] .

During the study period, 1318 patients received casirivimab/imdevimab in our three EDs.

Follow up was successful for 1222 (92.7%), and these patients were used for analysis. Among them, 16.2% were fully vaccinated, 4.5% were partially vaccinated (had only received one dose of Pfizer or Moderna), and 79.3% were unvaccinated. Table 1 shows a comparison of fully vaccinated, partially vaccinated, and unvaccinated patients for baseline characteristics and outcomes.

In the fully vaccinated group, 3.0% required admission to the hospital within 28 days as compared to 6.2% in unvaccinated patients (difference: 3.2% [95% CI 0.3 to 6.0%]). Otherwise, there were no statistically significant differences in univariate outcomes.

Regarding the primary outcome, our multivariate regression analysis found that for patients receiving casirivimab/imdevimab for COVID-19, full vaccination was associated with a statistically significant reduction in hospitalization within 28 days with an odds ratio of 0.19 (95% CI: 0.05 to 0.54) (p = 0.007). This is the first study to assess vaccination status in patients receiving monoclonal antibody therapy for COVID-19. Our study suggests that vaccination may further reduce the chance of hospitalization even after casirivimab/imdevimab. We did not find any evidence that J o u r n a l P r e -p r o o f vaccination reduces the risk of ICU admission or death in patients receiving casirivimab/imdevimab. However, our study was not powered to detect such differences, and in general, patients who receive casirivimab/imdevimab rarely require ICU care or die within 28 days, regardless of vaccination status. Interestingly, partially vaccinated patients trended towards having higher rates of hospitalizations and return ED visits, but the sample size for this group was too small to make definitive conclusions.

When interpreting the results of this study, there are some limitations to consider. As a retrospective study, the accuracy of our data is dependent upon the accuracy of documentation. Indeed, we did not include medical history in our analyses because upon initial review, chronic medical problems were noted to be inconsistently documented. That being said, vaccinated patients were older ( Table 1) J o u r n a l P r e -p r o o f

Uptake of Outpatient Monoclonal Antibody Treatments for COVID-19 in the United States: a Cross-Sectional Analysis

Neutralizing Antibody Cocktail, in Outpatients with Covid-19

REGEN-COV Antibody Cocktail Clinical Outcomes Study in Covid-19 Outpatients

Clinical profile and predictors of in-hospital mortality among older patients hospitalised for COVID-19

A brief-review of the risk factors for covid-19 severity

Racial Disparities in COVID-19 Testing and Outcomes : Retrospective Cohort Study in an Integrated Health System

Racial and Ethnic Differences in Presentation and Outcomes for Patients Hospitalized With COVID-19

Findings From the American Heart Association's COVID-19 Cardiovascular Disease Registry

Obesity a predictor of outcomes of COVID-19 hospitalized patients-A systematic review and meta-analysis