Related Experiment Video
Updated: Aug 11, 2025

Swabbing the Urban Environment - A Pipeline for Sampling and Detection of SARS-CoV-2 From Environmental Reservoirs
Published on: April 9, 2021
Cocirculation and replacement of SARS-CoV-2 variants in crowded settings and marginalized populations along the
Antoine Chaillon1, Ietza Bojorquez2, Jaime Sepúlveda3
1Division of Infectious Diseases and Global Public Health, University of California San Diego. San Diego, United States. achaillon@health.ucsd.edu.
Objective:
To interrogate the circulating SARS-CoV-2 lin-eages and recombinant variants in persons living in migrant shelters and persons who inject drugs (PWID).
Materials And Methods:
We combined data from two studies with marginalized populations (migrants in shelters and persons who inject drugs) in Tijuana, Mexico. SARS-CoV-2 variants were identified on nasal swabs specimens and compared to publicly available genomes sampled in Mexico and California.
Results:
All but 2 of the 10 lineages identified were predomi-nantly detected in North and Central America. Discrepan-cies between migrants and PWID can be explained by the temporal emergence and short time span of most of these lineages in the region.
Conclusion:
The results illustrate the temporo-spatial structure for SARS-CoV-2 lineage dispersal and the potential co-circulation of multiple lineages in high-risk populations with close social contacts. These conditions create the potential for recombination to take place in the California-Baja California border.
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