SARS-CoV-2 Omicron Variant Isolates Now Available

It has now been two years since the National Institute of Allergy and Infectious Diseases (NIAID) directed BEI Resources to prioritize reagents for the SARS-CoV-2 pandemic response, and BEI Resources remains committed to providing SARS-CoV-2 reagents to the research community. The BEI Resources catalog of SARS-CoV-2 reference and research reagents has expanded from the first cultured United States isolate (USA-WA1/2020; NR-52281) to more than 250 products. This includes isolates representing 13 WHO variants across 28 lineages and related reagents such as genomic RNA, proteins, inactivated virus preparations, proteins, peptide arrays and expression vectors for all 29 SARS-CoV-2 viral proteins. The newly added immunized pooled human sera are important as post-vaccination standard reference materials.1

Recent additions to the catalog include strains of the Variant of Concern Omicron (BEI Resources NR-56461, NR-56475 and NR-56481), the dominant SARS-CoV-2 variant currently circulating in the United States.2,3 These isolates originated in the United States and contain characteristic mutations in the Spike protein associated with increased transmission and reduced susceptibility to therapeutic agents or acquired immunity through immune evasion.2,4

All SARS-CoV-2 variants have been analyzed by Next Generation Sequencing with respect to both the SARS-CoV-2, Wuhan-Hu-1 strain reference sequence and the original reference sequence for that isolate to confirm signature mutations. Certificates of Analysis for each stock produced include observed sequence variations noted in the Appendix section and detailed lot-specific data such as passage history and titer of each lot.

This comprehensive resource of quality-controlled reference and research reagents is made available free-of-charge to registrants supporting the development and testing of SARS-CoV-2 diagnostics, therapeutics and vaccines. For more information on the ordering process and how to register, please refer to our Frequently Answered Questions or contact Customer Care at


BEI Resources 

Recently Added SARS-CoV-2 Isolates & Reagents


Isolate hCoV-19/Uganda/MUWRP-20200195568/2020 (Delta Variant)


Isolate hCoV-19/USA/MD-HP05285/2021 (Delta Variant), Heat Inactivated


Isolate hCoV-19/USA/MD-HP20874/2021 (Omicron Variant)


Isolate hCoV-19/USA/HI-CDC-4359259-001/2021 (Omicron Variant)


Isolate hCoV-19/USA/GA-EHC-2811C/2021 (Omicron Variant)


Pooled Human Serum Sample, Pfizer Vaccine


Pooled Human Serum Sample, Moderna Vaccine


Pooled Human Serum Sample, Johnson and Johnson Vaccine


Pooled Human Serum Sample, Novavax Vaccine


Genomic RNA from hCoV-19/USA/GA-EHC-2811C/2021 (Omicron Variant)


Isolate hCoV-19/USA/GA-EHC-2811C/2021 (Omicron Variant), Heat Inactivated




















  1. Xiang, J., et al. "Establishment of Human Post-Vaccination SARS-CoV-2 Standard Reference Sera." medRXiv (2022). doi: 10.1101/2022.01.24.22269773. Online ahead of print.
  2. "SARS-CoV-2 Variant Classifications and Definitions." Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, Accessed 18 February 2022.
  3. "Covid Data Tracker." Centers for Disease Control and Prevention, U.S. Department of Health and Human Services, Accessed 18 February 2022.
  4. "Omicron Variant Report.", Accessed 18 February 2022.

Image:  Scanning electron micrograph of a cell infected with SARS-CoV-2 UK B.1.1.7 virus particles (NIAID/CC BY 2.0)

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