High SARS-CoV-2 viral load in travellers arriving in Spain with a negative COVID-19 test prior to departure

Molero-Salinas, Andrea; Rico-Luna, Carla; Losada, Carmen; Buenestado‐Serrano, Sergio; García, Víctor Manuel Cueva; Egido, José; Adán‐Jiménez, Javier; Catalán, Pilar; Muñóz, Patricia; Pérez‐Lago, Laura; Viedma, Darı́o Garcı́a de

doi:10.1093/jtm/taab180

Cited by 7 publications

(5 citation statements)

References 8 publications

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“…This is to be expected given travellers will typically be earlier in their infection at the point of the arrival test, as noted above (Figure 2). Such a pattern is also consistent with previous reports of shedding being higher than usual among positive arriving travellers [22]. Based on protocols implemented, we estimated that arrival PCR testing at day 4 would have detected around 60% of infected individuals within the first 10 days of their infection if an epidemic in the departure location was growing at 10% per day (Figure 3E), and around 40% during an epidemic that was declining 10% per day (Figure 3F).…”

Section: Resultssupporting

confidence: 91%

“…To estimate the probability of detection at departure, we used the median estimate of testing PCR positive from a cohort study of self-tested healthcare workers [17], taking the first D=30 days post-infection in our analysis as the probability was negligible after this point. We assume PCR positivity post-infection for the wildtype variant is representative of positivity for subsequent variants [22]. As pre-departure PCR testing had to be within 72 hours of travel, in our baseline scenario we assumed travellers performed a PCR test 2 days before departure, with 1 day travel time to French Polynesia (i.e.…”

Section: Travel Testing Modelmentioning

confidence: 99%

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Real-time surveillance of international SARS-CoV-2 prevalence using systematic traveller arrival screening

Kucharski

Chung

Aubry

et al. 2022

Preprint

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Background: Effective COVID-19 response relies on good knowledge of infection dynamics, but owing to under-ascertainment and delays in symptom-based reporting, obtaining reliable infection data has typically required large dedicated local population studies. Although many countries implemented SARS-CoV-2 testing among travellers, interpretation of arrival testing data has typically been challenging because arrival testing data were rarely reported systematically, and pre-departure testing was often in place as well, leading to non-representative infection status among arrivals. Methods: In French Polynesia, testing data were reported systematically with enforced pre-departure testing type and timing, making it possible to adjust for non-representative infection status among arrivals. Combining statistical models of PCR positivity with data on international travel protocols, we reconstructed estimates of prevalence at departure using only testing data from arrivals. We then applied this estimation approach to the USA and France, using data from over 220,000 tests from travellers arriving into French Polynesia between July 2020 and March 2022. Findings: We estimated a peak infection prevalence at departure of 2.8% (2.3-3.6%) in France and 1.1% (0.81-3.1%) in the USA in late 2020/early 2021, with prevalence of 5.4% (4.8-6.1%) and 5.5% (4.6-6.6%) respectively estimated for the Omicron BA.1 waves in early 2022. We found that our infection estimates were a leading indicator of later reported case dynamics, as well as being consistent with subsequent observed changes in seroprevalence over time. Interpretation: As well as elucidating previously unmeasured infection dynamics in these countries, our analysis provides a proof-of-concept for scalable tracking of global infections during future pandemics.

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Section: Resultssupporting

confidence: 91%

Section: Travel Testing Modelmentioning

confidence: 99%

Real-time surveillance of international SARS-CoV-2 prevalence using systematic traveller arrival screening

Kucharski

Chung

Aubry

et al. 2022

Preprint

View full text Add to dashboard Cite

show abstract

“…This is to be expected given travellers will typically be earlier in their infection at the point of the arrival test, as noted above (Fig 2). Such a pattern is also consistent with previous reports of shedding being higher than usual among positive arriving travellers [22]. Based on protocols implemented, we estimated that arrival PCR testing at day 4 would have been expected to detect around 60% of infected individuals within the first 10 days of their infection if an epidemic in the departure location was growing at 10% per day (Fig 3E), and around 40% during an epidemic that was declining 10% per day (Fig 3F).…”

Section: Plos Medicinesupporting

confidence: 90%

Real-time surveillance of international SARS-CoV-2 prevalence using systematic traveller arrival screening: An observational study

Kucharski,

Chung,

Aubry

et al. 2023

PLoS Med

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Background Effective Coronavirus Disease 2019 (COVID-19) response relies on good knowledge of population infection dynamics, but owing to under-ascertainment and delays in symptom-based reporting, obtaining reliable infection data has typically required large dedicated local population studies. Although many countries implemented Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) testing among travellers, it remains unclear how accurately arrival testing data can capture international patterns of infection, because those arrival testing data were rarely reported systematically, and predeparture testing was often in place as well, leading to nonrepresentative infection status among arrivals. Methods and findings In French Polynesia, testing data were reported systematically with enforced predeparture testing type and timing, making it possible to adjust for nonrepresentative infection status among arrivals. Combining statistical models of polymerase chain reaction (PCR) positivity with data on international travel protocols, we reconstructed estimates of prevalence at departure using only testing data from arrivals. We then applied this estimation approach to the United States of America and France, using data from over 220,000 tests from travellers arriving into French Polynesia between July 2020 and March 2022. We estimated a peak infection prevalence at departure of 2.1% (95% credible interval: 1.7, 2.6%) in France and 1% (95% CrI: 0.63, 1.4%) in the USA in late 2020/early 2021, with prevalence of 4.6% (95% CrI: 3.9, 5.2%) and 4.3% (95% CrI: 3.6, 5%), respectively, estimated for the Omicron BA.1 waves in early 2022. We found that our infection estimates were a leading indicator of later reported case dynamics, as well as being consistent with subsequent observed changes in seroprevalence over time. We did not have linked data on traveller demography or unbiased domestic infection estimates (e.g., from random community infection surveys) in the USA and France. However, our methodology would allow for the incorporation of prior data from additional sources if available in future. Conclusions As well as elucidating previously unmeasured infection dynamics in these countries, our analysis provides a proof-of-concept for scalable and accurate leading indicator of global infections during future pandemics.

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“…WGS identified B.1.621 (Mu) to be the most frequently occurring variant, but others were also found, including Alpha, Beta, Gamma, and Delta. This showed potentially infectious passengers on board but did not trace their contacts to identify in-flight transmission [ 54 ] July 2021 Philippines, United Arab Emirates New Zealand Traveler A arrived from the Philippines and traveler E from a 5-person travel group (BCDEF) from UAE tested positive. Travelers B, C, and D subsequently tested positive; viral sequences matched A In the MIF, traveler A and group BCDEF occupied rooms > 2 m apart across a hall and never had direct contact [ 55 ] Other transport or group travel January 2020 China China (Beijing ex Wuhan) A family of 3 travelled by train from Beijing to Wuhan to visit the younger son.…”

Section: Travel-related Transmission Of Covid-19mentioning

confidence: 99%

“…Despite pre-departure negative tests, whole genome sequencing indicated inflight transmission between Dubai and Auckland based on testing performed shortly after arrival while in managed isolation and quarantine, although the pre-departure testing had been performed 4 to 5 days before departure [ 50 •]. Similarly, some travelers were found to have a high viral load (low cycle threshold value) on arrival in Spain despite negative pre-travel tests [ 54 ]. A modeling analysis of different strategies found that the risk of imported infection could be reduced by 80–90% through the use of testing on arrival and 7- or 14-day quarantine for test-negative individuals (relative to no testing) [ 73 ].…”

Section: Covid-19 Mitigation and Control Measuresmentioning

confidence: 99%

Travel in the Time of COVID: A Review of International Travel Health in a Global Pandemic

Flaherty

Hamer

Chen

2022

Curr Infect Dis Rep

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Purpose of Review This review critically considers the impact of the COVID-19 pandemic on global travel and the practice of travel medicine, highlights key innovations that have facilitated the resumption of travel, and anticipates how travel medicine providers should prepare for the future of international travel. Recent Findings Since asymptomatic transmission of the virus was first recognized in March 2020, extensive efforts have been made to characterize the pattern and dynamics of SARS-CoV-2 transmission aboard commercial aircraft, cruise ships, rail and bus transport, and in mass gatherings and quarantine facilities. Despite the negative impact of further waves of COVID-19 driven by the more transmissible Omicron variant, rapid increases of international tourist arrivals are occurring and modeling anticipates further growth. Mitigation of spread requires an integrated approach that combines masking, physical distancing, improving ventilation, testing, and quarantine. Vaccines and therapeutics have played a significant role in reopening society and accelerating the resumption of travel and further therapeutic innovation is likely. Summary COVID-19 is likely to persist as an endemic infection, and surveillance will assume an even more important role. The pandemic has provided an impetus to advance technology for telemedicine, to adopt mobile devices and GPS in contact tracing, and to apply digital applications in research. The future of travel medicine should continue to harness these novel platforms in the clinical, research, and educational arenas.

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High SARS-CoV-2 viral load in travellers arriving in Spain with a negative COVID-19 test prior to departure

Cited by 7 publications

References 8 publications

Real-time surveillance of international SARS-CoV-2 prevalence using systematic traveller arrival screening

Real-time surveillance of international SARS-CoV-2 prevalence using systematic traveller arrival screening

Real-time surveillance of international SARS-CoV-2 prevalence using systematic traveller arrival screening: An observational study

Travel in the Time of COVID: A Review of International Travel Health in a Global Pandemic

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