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SARS-CoV-2 Sample Positivity in Travellers Can Predict Community Prevalence Rates: Data from the Traveller-Based Genomic Surveillance Programme
28 Pages Posted: 9 Feb 2024
More...Abstract
Background: As SARS-CoV-2 testing has declined globally, disease prevalence is challenging to estimate due to limited data. CDC’s Traveller-based Genomic Surveillance (TGS) programme collects voluntary samples from arriving international travellers for early detection of SARS-CoV-2 variants and trends. We assessed the correlation between traveller post-arrival sample positivity rates and reported community rates for six countries.
Methods: Nasal samples from arriving travellers at select U.S. airports were pooled into groups by country of origin and RT-PCR-tested for SARS-CoV-2. SARS-CoV-2 positivity rates from travellers who arrived from six countries during December 6, 2021–January 22, 2023, were compared to the Johns Hopkins University Center for Systems Science and Engineering case data. For the United Kingdom, we also compared traveller rates to the UK Coronavirus Infection Survey household study data. Correlation analyses were conducted by country and divided into intervals to control for time-varying confounders. Correlations between traveller sample positivity estimates and corresponding community case rates and household study positivity estimates were assessed (Spearman’s rank).
Findings: There was high concordance between traveller and community rates for the six countries studied; 66·67% of time intervals showed significant correlation (p<0·05). After June 11, 2022, when a negative pre-departure SARS-CoV-2 test was no longer required one day prior to boarding flights to the United States, there was a strong correlation between sample positivity rates among travellers arriving from the United Kingdom and positivity estimates from the UK household study.
Interpretation: The TGS programme may provide data to fill gaps in global surveillance, particularly when country-level testing is limited.
Funding: CDC.
Declaration of Interest: Benjamin H. Rome, Siyao Lisa Li, Andrew P. Rothstein, and Robert C. Morfino were employed by Ginkgo Bioworks and owned Ginkgo Bioworks employee stocks or restricted stock units (RSU) grants during the preparation of the manuscript. Ezra T. Ernst is employed by XWELL and owns XWELL employee stocks or RSU grants. Nathan D. Grubaugh is contracted with U.S. CDC. No other potential conflicts of interest were disclosed.
Ethical Approval: This activity was reviewed by CDC and was conducted consistent with applicable federal law and CDC policy (e.g., 45 C.F.R. part 46.102(l)(2), 21 C.F.R. part 56; 42 U.S.C. §241(d); 5 U.S.C. §552a; 44 U.S.C. §3501 et seq).
Keywords: SARS-CoV-2, COVID-19, surveillance, travelers, air travel
Suggested Citation: Suggested Citation