Top 5 Takeaways

1. Early Reinfections Identified: Ten patients from four states had confirmed Omicron variant infections within 90 days of a previous Delta infection.
2. Age and Demographics: The median age at first infection was 11 years, with eight patients under 18 years old, one long-term care facility resident, and one healthcare worker.
3. Vaccination Status: Only three patients had received any COVID-19 vaccination, with one having completed a 2-dose mRNA series before the first infection.
4. Symptom Duration: Nine patients were symptomatic during the first infection, and six were symptomatic during reinfection, with a shorter median duration of symptoms during reinfection.
5. Challenges in Detection: Limited capacity for strain testing and the increasing use of at-home antigen tests hinder the identification of early reinfections.

Original Article Author and Citation

Corresponding Author

Brian Borah, rhz7@cdc.gov

Suggested Citation

Roskosky M, Borah BF, DeJonge PM, et al. Notes from the Field: SARS-CoV-2 Omicron Variant Infection in 10 Persons Within 90 Days of Previous SARS-CoV-2 Delta Variant Infection — Four States, October 2021–January 2022. MMWR Morb Mortal Wkly Rep 2022;71:524–526. DOI: http://dx.doi.org/10.15585/mmwr.mm7114a2

Summary

This report describes 10 patients from four states who had confirmed Omicron variant infections within 90 days of a previous Delta infection. The median age at first infection was 11 years, with most patients being under 18 years old. Only three patients had received any COVID-19 vaccination. Symptom duration was shorter during reinfection compared to the first infection. The study highlights the challenges in detecting early reinfections due to limited strain testing capacity and the use of at-home antigen tests.

Methods

An early reinfection was defined as a SARS-CoV-2 whole genome sequencing (WGS) test result from a new NAAT-positive specimen collected within 90 days of a first positive specimen from a previous WGS-confirmed SARS-CoV-2 infection, demonstrating a different lineage. Data were collected from Vermont, Wisconsin, Washington, and Rhode Island through public health surveillance and longitudinal research.

Discussion

The findings suggest that early reinfections with different SARS-CoV-2 variants can occur within a short period. The study underscores the potential limits of infection-induced immunity against novel variants and the importance of vaccination. Limited capacity for strain testing and the increasing use of at-home antigen tests pose challenges for identifying early reinfections.

Conclusion

This study highlights the importance of vaccination in preventing SARS-CoV-2 infections, even among those with previous infections. It also emphasizes the need for expanded genomic surveillance to better understand and detect early reinfections with distinct lineages.

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