The goal of this study is to compare real-world effectiveness of the mRNA-1273 vaccine versus the BNT162b2 vaccine on medically attended COVID-19 and COVID-19 hospitalizations among fully vaccinated immunocompromise participants.

This observational retrospective comparative effectiveness cohort study will use the HealthVerity aggregated medical and pharmacy claims database. HealthVerity data elements include provider-submitted claims, adjudicated insurance claims, and pharmacy billing manager claims submissions. Hospitalizations are included in the data at a summary level.

Inclusion Criteria:

• Fully vaccinated with a currently US authorized COVID-19 vaccine:
• 2 doses of mRNA-1273 (minimum 14 days between doses)
• 2 doses of BNT1262b2 (minimum 14 days between doses)
• Continuous enrollment in medical & pharmacy plan for at least 365 days prior to index/Cohort entry date (CED)
• Identified as immunocompromised via at least 1 of the following criteria at index/CED
• Evidence of blood or stem cell transplant in 2 years prior to index/CED
• Any history of organ transplant and taking immunosuppressive therapy within the 60 days prior to index/CED
• Evidence of active cancer treatment in the 180 days prior to index/CED with an active cancer diagnosis in the 365 days prior to treatment
• Any prior history of a primary immunodeficiency disorder (for example, for conditions such as DiGeorge syndrome and Wiskott-Aldrich syndrome)
• Any history of an HIV diagnosis code prior to index/CED
• A fill for an immunosuppressive therapy in the 60 days prior to index/CED

Exclusion Criteria:

• Prior COVID-19 infection (any history prior to index/CED through day 13 post-completion of vaccine regimen) identified via the following diagnosis codes on an inpatient or outpatient claim:
• U07.1: "COVID-19, virus identified"
• J12.82: "Pneumonia due to COVID-19"
• Z86.16: "Personal history of COVID-19"
• The following diagnosis codes were utilized early in the pandemic. Exclusion will be applied March 1, 2020 through day 13 post-completion of vaccine regimen:
• J12.89: "Other viral pneumonia"
• J20.8: "Acute bronchitis due to other specified organisms"
• J40: "Bronchitis, not specified as acute or chronic"
• J22: "Unspecified acute lower respiratory infection"
• J98.8: "Other specified respiratory disorders"
• J80: "Acute respiratory distress syndrome"
• Prior receipt of a heterologous COVID-19 vaccine (relative to the COVID-19 vaccine identified at index/CED) in the 365 days prior to index/CED through 13 days post-completion of vaccine regimen
• Receipt of an additional dose of homologous COVID-19 vaccine between index/CED and 13 days post-completion of vaccine regimen
• Missing or unknown gender on index/CED

The study population will be selected from HealthVerity's aggregated medical and pharmacy claims database that represents healthcare utilization for participants between 01 December 2018 and 10 January 2022.