ABSTRACT
Background. International travel facilitates SARS-CoV-2 spread globally. Early detection of variants among arriving international travelers could provide viral information about introduction of variants with differing infectivity, virulence, and vaccine effectiveness, enabling adjustments to treatment and prevention strategies. We initiated a genomic surveillance program at 4 US airports to detect SARS-CoV-2 variants among arriving international travelers. Methods. Between November 29, 2021-April 24, 2022, we enrolled arriving air travelers (>=18 years) from flights originating in 16 countries on 5 continents. At four airports, participants self-collected nasal swab samples that were pooled with 5-25 other samples by country of flight. Participants were also given a take-home saliva collection kit;saliva was collected 3-5 days after arrival and mailed back to the laboratory. SARS-CoV-2 reverse transcription-polymerase chain reaction (RT-PCR) was performed on all samples at the laboratory. Positives underwent whole genome sequencing. Demographic, clinical, and travel information was collected. Results. We enrolled 28,656 travelers;median age was 42 years (interquartile range 31-55), 48% were female, and 99.4% self-reported COVID-19 vaccination. Overall, 19%(504/2,666) of pooled and 7.5%(285/3804) of individual samples were positive for SARS-CoV-2. Highest pool positivity of 46% occurred during January 3-10, 2022 (Figure 1).Omicron variant accounted for 97%of sequences (Figure 2).We detected the earliest reporting of Omicron sub-lineages BA.2 and BA.3 (7 and 43 days earlier than reported elsewhere) in the United States and North America, respectively. During April 4-18, we detected an increasing trend of pool positivity among travelers on South African flights, detecting one of the first US-reported BA.4 sub-lineages consistent with early surge of cases in South Africa. Weekly pooled positivity for travelers on South African flights aligned with World Health Organization (WHO)-reported 7-day COVID-19 incidence rates over the same period (Figure 3). ] Conclusion. This genomic sequencing surveillance platform is a model for traveler-based SARS-CoV-2 genomic surveillance that can be used as an early warning system to detect future outbreaks and pandemics. (Figure Presented).
ABSTRACT
Background. In January-March 2020, the Centers for Disease Control and Prevention (CDC) issued multiple warnings regarding COVID-19 travel-associated risks. We sought to describe US travelers seeking pretravel consultation regarding international travel at US Global TravEpiNet (GTEN) sites before and after the initial COVID-19 travel warnings. Methods. We prospectively collected data at 22 GTEN sites pre-COVID-19 (January-December 2019) and 18 GTEN sites during the COVID-19 pandemic (April 2020-March 2021). We excluded travelers evaluated during January-March 2020, when CDC travel guidance was evolving rapidly. Travelers used standardized questionnaires to self-report data regarding demographics and travel-related characteristics. Providers confirmed these data and documented their recommendations during pretravel consultation, which could be performed virtually. We conducted descriptive analyses of differences in demographics, travel-related characteristics, vaccinations, and medications (SAS v9.4;Cary, NC). Results. Compared with 16,903 pre-COVID-19 consultations, only 1,564 consultations occurred during the COVID-19 pandemic, a 90% reduction (Table). During COVID-19, a greater proportion of travelers were children aged 1-5 years, visiting friends and relatives (VFR), with itineraries ≥ 30 days, and going to Africa;a smaller proportion of travelers were aged > 55 years, or traveling to Southeast Asia or the Western Pacific. During COVID-19, fewer vaccine-eligible travelers received vaccines at the pretravel consultation except for yellow fever, and a greater proportion were referred to another provider for vaccination (Figure). Table. Demographics and travel-related characteristics of international travelers seeking pretravel consultation at Global TravEpiNet sites before and during the COVID-19 pandemic Table continued. Demographics and travel-related characteristics of international travelers seeking pretravel consultation at Global TravEpiNet sites before and during the COVID-19 pandemic Figure. Vaccinations and reasons for nonvaccination among vaccine-eligible international travelers at pretravel consultations at Global TravEpiNet (GTEN) sites before and during the COVID-19 pandemic. Among vaccine-eligible travelers, we summarized those who were vaccinated at the visit (blue) and not vaccinated (orange). We then categorized reasons for nonvaccination into: provider decision (solid), referral to another provider (dots), traveler refusal (striped), or other (hatched). COVID-19 vaccination was not available at GTEN sites during the analysis period;although COVID-19 vaccinations outside of GTEN sites might have affected vaccination recommendations, they were unlikely to have had a large effect given their limited availability in January-March 2021. Conclusion. Compared with pre-COVID-19, US travelers seeking pretravel consultations at GTEN sites during the pandemic might be at higher risk for travel-related infections given VFR status, traveling for ≥ 30 days, and going to Africa. Fewer vaccine-eligible travelers were vaccinated at pretravel consultations, which could reflect more virtual pretravel consultations. Counseling and vaccination for international travelers continue to be priorities during the COVID-19 pandemic.