Estimating Infection Prevalence in Wuhan City, China from Repatriation

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Estimating infection prevalence in Wuhan City, China from repatriation flight data Hayley A Thompson1*, Natsuko Imai1, Amy B Dighe1, Kylie Ainslie1, Marc Baguelin1, Sangeeta Bhatia1, Samir Bhatt1, Adhiratha Boonyasiri1,2, Olivia Boyd1, Nicholas F Brazeau1, Lorenzo Cattarino1, Laura V Cooper1, Helen Coupland1, Zulma Cucunuba1, Gina Cuomo-Dannenburg1, Bimandra Djaafara1, Ilaria Dorigatti1, Sabine Leonore vanElsland1, Richard FitzJohn1, Han Fu1, Katy Gaythorpe1, Will Green1, Timothy Hallett1, Arran Hamlet1, David Haw1, Sarah Hayes1, Wes Hinsley1, Benjamin Jeffrey1, Edward Knock1, Daniel J Laydon1 , John Lees1, Tara D Mangal1, Thomas Mellan1, Swapnil Mishra1, Andria Mousa1, Gemma Nedjati-Gilani1, Pierre Nouvellet1,3, Lucy Okell1, Kris V Parag1, Manon Ragonnet-Cronin1, Steven Riley1, H. Juliette T Unwin1, Robert Verity1, Michaela Vollmer1, Erik Volz1, Patrick G T Walker1, Caroline Walters1, Haowei Wang1, Yuanrong Wang1, Oliver J Watson1, Charles Whittaker1, Lilith K Whittles1, Peter Winskill1, Xiaoyue Xi4, Christl A Donnelly1,5 & Neil M Ferguson1

Affiliations: 1. MRC Centre for Global Infectious Disease Analysis, Abdul Latif Jameel Institute for Disease and Emergency Analytics, and Department of Infectious Disease Epidemiology, Imperial College London, London, UK 2. NIHR Health Protection Research Unit in Healthcare Associated Infections and Antimicrobial Resistance, Imperial College London 3. School of Life Sciences, University of Sussex, UK 4. Department of Mathematics, Imperial College London, London, UK 5. Department of Statistics, University of Oxford, Oxford, UK

*Corresponding author: Ms Hayley Thompson, MRC Centre for Global Infectious Disease Analysis, Imperial College, Norfolk Place, London, W2 1NY. [email protected]

(Submitted: 21 April 2020 – Published online: 23 April 2020)

DISCLAIMER This paper was submitted to the Bulletin of the World Health Organization and was posted to the COVID-19 open site, according to the protocol for public health emergencies for international concern as described in Vasee Moorthy et al. (http://dx.doi.org/10.2471/BLT.20.251561).

The information herein is available for unrestricted use, distribution and reproduction in any medium, provided that the original work is properly cited as indicated by the Creative Commons Attribution 3.0 Intergovernmental Organizations licence (CC BY IGO 3.0).

RECOMMENDED CITATION Thompson HA, Imai N, Dighe AB, Ainslie K, Baguelin M, Bhatia S, et al. Estimating infection prevalence in Wuhan City, China from repatriation flight data. [Preprint]. Bull World Health Organ. E-pub: 23 April 2020. doi: http://dx.doi.org/10.2471/BLT.20.260307

Abstract

Objective: To characterise the infection prevalence of SARS-CoV-2 over time from repatriates returning from Wuhan City, China between 29th January – 27th February 2020.

Methods: We identified and tracked countries that were repatriating citizens on chartered flights departing Wuhan City between 29th January to the 27th February 2020. Data were curated from publicly available government or media sources, on the number of people repatriated, the number of people undergoing PCR testing and the symptomatic status of individuals being tested. We pooled these data and estimated the overall infection prevalence and a per-flight infection prevalence estimate over time.

Findings: We identified 56 flights that repatriated a total of 8597 people to 55 different countries over the time period considered. Pooling the available data, we estimated overall infection prevalence to be 0.87% (95% CI: 0.32 – 1.89%) in Wuhan City, China. Infection prevalence was generally low across all flights with point estimates below 2% (range: 0 %– 1.9%). We observed a declining trend in infection prevalence over time; however, this was not statistically significant.

Conclusion: Where population-level testing is not feasible during an outbreak, these repatriated cohorts provide snapshots of the infection prevalence over time in Wuhan City. Such early studies can be used to understand the potential scale of the epidemic and have subsequently helped to inform the ongoing global response and research into COVID-19. Introduction

The outbreak of a novel coronavirus (coronavirus disease 2019 (COVID-19)), caused by the SARS-CoV-2 virus, was declared a global pandemic by the World Health Organization (WHO) on 11th March 2020 [1]. The virus was first detected in Wuhan City, China in late 2019 and has subsequently spread to over 200 countries states and territories across the globe [2]. China implemented strict travel and movement restrictions in Wuhan City following the detection of the outbreak which led to foreign governments chartering flights to repatriate citizens from the then epicentre of the outbreak. These flights began on 29th January 2020 and continued up to the point of our analysis on 27th February 2020. Repatriates underwent quarantine upon arrival in their home countries and many countries implemented PCR to test for infection regardless of symptoms. These repatriation flights therefore provide snapshots of infection prevalence over time and give us insights into the levels of transmission in Wuhan City where large-scale prevalence surveys were unfeasible given the scale of the outbreak and the response needed to contain it. We present an overview of these repatriation flights within this timeframe and estimate the infection prevalence over time.

Methods

Data Collection

We identified countries that were scheduling repatriation flights through following international and local news outlets and the press releases of government departments including Ministries of Foreign Affairs and Ministries of Health. Once flights were identified we curated a list of key variables to track during the quarantine periods (Table 1). These variables included the total number of repatriates per flight and their final destinations, the number of those who were tested on arrival, during and before release from quarantine and the number who tested positive. In addition, we collected information on the number of people who tested positive while being asymptomatic or symptomatic.

Statistical Analysis

All analysis was performed using R Statistical Software version 3.6.3 [3]. The primary outcome was a confirmed PCR positive test result for SARS-CoV-2 infection. For the repatriation flights where all passengers were tested regardless of presence or absence of symptoms, we estimated the infection point prevalence as the number of positive test results divided by the total tested population and the corresponding exact 95% binomial confidence intervals [4]. To test for any association between date of repatriation flight and the level of infection prevalence we performed a logistic regression on the binomial count data over time. The dependent variable was confirmed SARS-CoV-2 infection (positive = 1, negative = 0) and the categorical predictor variable was the date of flight over the study period in question (29th January 2020 – 27th February 2020). Results

A total of 8597 persons were repatriated over 56 flights from Wuhan City carrying citizens from 55 different countries (Table 1). Figure 1 highlights the countries (and the number of repatriation flights bycountry) where repatriates underwent their quarantine periods. As some flights were shared between two or more countries e.g. USA and Canada, the map shows the countries that chartered the primary flight out of Wuhan and therefore the destination of quarantine for the majority of passengers on-board. Quarantine periods were defined and carried out by governments following the arrival of the repatriation flights in country. Most countries implemented 14-day quarantine periods to reduce the risk of local onward transmission from this at- risk population. This follows WHO advice based on estimates that the maximum incubation period of the virus is around 14 days [5]. During this time the majority of countries tested for SARS-CoV-2 infection in symptomatic and asymptomatic repatriates, at multiple time points. The supplementary table outlines the testing procedures that have been made publicly available.

While testing procedures varied, we identified 47 repatriation flights that tested for SARS-CoV-19 infection in their passengers resulting in a total tested population of 5,720 individuals. Of these passengers a total of 36 tested positive for SARS-CoV-2 infection resulting in an overall infection prevalence of 0.63% (95% CI: 0.44% - 0.87%). However, only 32 out of the 47 repatriation flights tested everyone regardless of symptoms (we include the first Japanese flight where 204 of 206 passengers were tested). Only considering these flights, the overall infection prevalence was 0.60% (95% CI: 0.41% -0.86%).

Finally, repatriation flights had different testing protocols (Supplementary Table), and amongst the 47 flights that tested for SARS-CoV-2 infection, 20 tested upon arrival. Quarantine measures also differed slightly by country, with some individuals undergoing quarantine at home rather than in a designated facility. Accounting for the possibility individuals may have been infected on the flight itself and thus later test positive, to estimate a conservative point prevalence of infection, we estimated infection prevalence from flights that tested passengers immediately upon arrival. Of 2433 passengers tested immediately upon arrival, 13 individuals tested positive upon the initial test, giving an infection prevalence of 0.53% (95% CI: 0.28% - 0.91%). Over the 6 flights arriving between 30th January 2020 and 1st February inclusive (close to the peak of the epidemic in Wuhan) where everyone was tested on arrival, the infection prevalence was 0.87% (6/689, 95% CI: 0.32% - 1.89%).

Figure 2 shows the infection prevalence (amongst those who tested positive on the first test) from each of the repatriation flights that tested all passengers upon arrival based on the flight date from Wuhan City. Infection point prevalence was generally low (<2%) across these flights, with flights at the end of January reporting a slightly higher prevalence than those at the end of February. While flights at the beginning of the time period reported a slightly higher infection prevalence than those at the end of the time period, a trend similar to the declining epidemic trend in the Wuhan over the same time period [6], this was not statistically significant (p- value = 0.11).

Across the 32 flights testing passengers regardless of symptoms on arrival, 9 individuals tested positive giving an asymptomatic infection prevalence of 0.36% (95% CI 0.16% - 0.70%). Of these 9 individuals, we were able to find follow-up reports that indicated two individuals in Japan went on to develop symptoms of COVID-19 [7], five others in Japan and Germany remained asymptomatic throughout the course of their quarantine [8-11]. It was unclear whether the remaining two asymptomatic positives went on to develop symptoms.

Discussion

In this study we have provided a snapshot of the infection prevalence in Wuhan city across a four-week period from repatriated cohorts. We estimated a low prevalence of SARS-CoV-2 infection across all flights that tested everyone on arrival regardless of symptoms of less than 2% and a pooled infection prevalence of 0.53% (95% CI 0.28% - 0.91%). We observed the highest point prevalence of infection at the beginning of the time period. While the deployment of large-scale seroprevalence studies are beginning to get underway, testing of repatriated cohorts provided an indication of the level of transmission in the wider population. By focusing on repatriated cohorts and particularly flights where all passengers were tested regardless of symptoms and tested multiple times by PCR, a more accurate estimate of infection prevalence can be obtained.

As the spread of the virus and the burden of COVID-19 accelerates globally, it is increasingly important to understand the prevalence of infection in the population. This helps to refine estimates of the case and infection fatality ratios in different population groups [12]. In conjunction with large-scale serological studies infection prevalence estimates can also help governments understand the true scale of the epidemic and the potential impacts of relaxing social distancing measures. However large-scale seroprevalence testing is challenging to undertake during the peak of the epidemic. With countries beginning to repatriate citizens from other countries, for example the British government recently announced plans to charter 7 flights for citizens in India [13], the testing of these cohorts can continue to provide insights about how far along in the epidemic countries are and the level of response necessary to help control epidemics unfolding globally. Some seroprevalence surveys are currently underway in countries at different stages of the epidemic and will be vital to understanding the levels of current and historic infection across the globe. Early results from large-scale PCR population testing in Iceland indicate an infection prevalence of 0.8% (95% CI, 0.6% to 1.0%) from the first 10,797 samples [14]. While Wuhan City and Iceland differ in the stage of their epidemics and control measures introduced, our estimates are consistent in terms of the magnitude of community spread.

The evidence of asymptomatic PCR-positive individuals in these cohorts highlights that clinical screening is not always effective at identifying infected and therefore potentially infectious individuals. Studies have suggested there is some pre-symptomatic and asymptomatic transmission of the SARS-CoV-2 virus [15-23]. Identifying asymptomatic and pre-symptomatic individuals will be central to reducing the spread of virus and preventing a second wave of infections as countries start to consider how and when to relax social distancing interventions such as school-closures, closure of non-essential shops, and “shelter-at-home” orders.

Our analysis has some additional limitations. The information on testing protocols and the delay from repatriation to testing was often sparse and differed by country. The conditions under which repatriated citizens were quarantined also varied by country which could have facilitated transmission within the cohorts. Since this could bias estimates of infection prevalence, we considered the infection prevalence amongst individuals from flights who were tested upon arrival as our main outcome. These flights represent a globally diverse population of foreign nationals who were in Wuhan City leading up to the outbreak for variable periods of time and for a variety of reasons: students, work-related travel, visiting friends and families and tourism, it is unclear whether the risk of infection posed to these individuals was comparable to the risk of infection within the general population in Wuhan City.

Whilst representative community-based seroprevalence studies will be required to understand the true burden of the epidemic. Estimates of infection prevalence amongst repatriated citizens can give early insights into the potential scale of the epidemic within different populations.

Funding

This work was funded by joint Centre funding from the UK Medical Research Council and Department for International Development.

Contributions HAT, NI, CAD, NMF conceived the study; HAT, NI, AD, WG, GCD, KAMG, HF collected and extracted the international flight data and information on testing strategies; HAT and NI carried out the analysis; HAT wrote the first draft of the manuscript with input from NI and AD; all authors contributed to the final draft.

References

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japan_fl1 2020-01-29 206 204 5 arrival 3 1 2 1 4 1 2020-02-12 yes usa_fl1 2020-01-29 195 195 0 arrival 0 0 0 0 0 0 2020-02-11 yes japan_fl2 2020-01-30 210 210 5 arrival 2 0 2 0 3 2 2020-02-07 yes singapore_fl1 2020-01-30 92 92 5 unknown 1 1 0 0 2 3 2020-02-13 yes japan_fl3 2020-01-31 149 149 3 arrival 2 1 1 1 2 1 2020-02-14 yes uk_fl1 2020-01-31 109 25 0 unknown 0 0 0 0 0 0 2020-02-15 yes southkorea_fl1 2020-01-31 368 368 2 unknown 2 0 0 0 0 0 2020-02-15 yes france_fl1 2020-01-31 180 180 0 arrival 0 0 0 0 0 0 2020-02-14 yes germany_fl1 2020-02-01 115 115 2 arrival 2 0 2 0 0 2 2020-02-16 yes southkorea_fl2 2020-02-01 333 333 0 unknown 0 0 0 0 0 0 2020-02-16 yes jordan_fl1 2020-02-01 71 25 0 later 0 0 0 0 0 0 2020-02-10 yes india_fl1 2020-02-01 324 324 0 unknown 0 0 0 0 0 0 2020-02-18 yes mongolia_fl1 2020-02-01 31 31 0 arrival 0 0 0 0 0 0 2020-02-19 yes turkey_fl1 2020-02-01 42 42 0 unknown 0 0 0 0 0 0 2020-02-14 yes saudiarabia_fl1 2020-02-02 10 10 0 unknown 0 0 0 0 0 0 2020-02-17 yes indonesia_fl1 2020-02-02 243 0 0 - 0 0 0 0 0 0 2020-02-15 yes france_fl2 2020-02-02 254 215 1 unknown 1 0 0 0 0 0 2020-02-16 yes kazakhstan_fl1 2020-02-02 89 89 0 unknown 0 0 0 0 0 0 2020-02-16 yes india_fl2 2020-02-02 330 330 0 unknown 0 0 0 0 0 0 2020-02-19 yes italy_fl1 2020-02-03 56 56 1 later 1 1 0 0 1 0 2020-02-21 yes taiwan_fl1 2020-02-03 247 5 1 arrival 1 1 0 0 1 0 2020-02-18 yes morocco_fl1 2020-02-03 167 167 0 unknown 0 0 0 0 0 0 2020-02-22 yes egypt_fl1 2020-02-03 301 301 0 unknown 0 0 0 0 0 0 2020-02-17 yes uzbekistan_fl1 2020-02-04 250 250 0 arrival 0 0 0 0 0 0 2020-02-18 yes thailand_fl1 2020-02-04 138 138 1 arrival 0 5 0 0 1 0 2020-02-22 yes malaysia_fl1 2020-02-04 107 107 2 arrival 2 0 2 0 0 0 2020-02-18 yes australia _fl1 2020-02-04 242 14 0 unknown 0 0 0 0 0 0 2020-02-18 yes usa_fl2 2020-02-05 178 1 0 unknown 0 0 0 0 0 0 2020-02-18 yes usa_fl3 2020-02-05 166 5 1 unknown 1 1 0 0 1 0 2020-02-18 yes uzbekistan_fl2 2020-02-05 84 84 0 arrival 0 0 0 0 0 0 2020-02-19 yes newzealand_fl 2020-02-05 193 2 0 unknown 0 0 0 0 0 0 2020-02-19 yes 1 russia_fl1 2020-02-05 144 144 0 unknown 0 0 0 0 0 0 2020-02-19 yes iran_fl1 2020-02-05 141 56 0 unknown 0 0 0 0 0 0 2020-02-17 yes

Table 1: Summary of repatriation flight from Wuhan City, China Positi Asymptoma Numb Total Date Date Number Point ve at Symptomatic Asymptomatic tic and later Total Total Quarantine Flight ID er positive quarantine repatriated repatriated tested initial at initial test at initial test developed symptomatic asymptomatic ended* tested confirmed ended test symptoms canada_fl1 2020-02-06 176 0 0 - 0 0 0 0 0 0 2020-02-21 yes uzbekistan_fl3 2020-02-06 251 251 0 arrival 0 0 0 0 0 0 2020-02-20 yes japan_fl4 2020-02-07 198 198 1 arrival 1 1 0 0 1 0 2020-02-21 yes usa_fl4 2020-02-07 104 2 1 unknown 1 1 0 0 1 0 2020-02-20 yes usa_fl5 2020-02-07 148 2 1 unknown 1 0 0 0 0 0 2020-02-20 yes brazil_fl1 2020-02-08 40 34 0 arrival 0 0 0 0 0 0 2020-02-23 yes brunei_fl1 2020-02-08 2 0 0 - 0 0 0 0 0 0 NA yes inferred singapore_fl2 2020-02-09 174 174 2 unknown 0 0 0 0 0 2 NA yes inferred philippines_fl1 2020-02-09 49 0 0 - 0 0 0 0 0 0 2020-02-22 yes uk_fl2 2020-02-09 200 179 0 unknown 0 0 0 0 0 0 2020-02-23 yes australia_fl2 2020-02-09 266 0 0 - 0 0 0 0 0 0 2020-02-25 yes vietnam_fl1 2020-02-10 30 30 0 unknown 0 0 0 0 0 0 2020-02-21 yes canada_fl2 2020-02-11 185 0 0 - 0 0 0 0 0 0 NA yes inferred southkorea_fl3 2020-02-12 147 145 0 arrival 0 0 0 0 0 0 2020-02-13 yes japan_fl5 2020-02-16 65 65 1 arrival 1 1 0 0 1 0 2020-02-17 yes nepal_fl1 2020-02-16 175 175 0 arrival 0 0 0 0 0 0 2020-03-02 yes ukraine_fl1 2020-02-20 74 74 0 later 0 0 0 0 0 0 NA yes inferred france_fl3 2020-02-20 63 43 1 unknown 0 0 0 0 0 1 NA yes inferred malaysia_fl2 2020-02-25 66 66 0 arrival 0 0 0 0 0 0 NA yes colombia_fl1 2020-02-27 15 15 0 arrival 0 0 0 0 0 0 NA yes sri lanka_fl1 2020-02-01 33 0 0 - 0 0 0 0 0 0 NA yes inferred bangladesh_fl1 2020-01-31 312 0 0 - 0 0 0 0 0 0 2020-02-16 yes myanmar_fl1 2020-02-02 59 0 0 - 0 0 0 0 0 0 NA yes inferred 1We inferred that quarantine had ended if more than 14 days had passed since the date of repatriation. For these flights we were not able to find exact reports or dates of release.

Figure.1. Countries where citizens who have been repatriated from Wuhan City have undergone quarantine. Some countries offered quarantine for citizens of other countries and as such these nations while having citizen repatriated are not shown in this map.

Figure.2. Infection prevalence (points, bars = exact binomial 95% CI) amongst repatriation flights where all passengers were tested for SARS-CoV-2 infection regardless of symptoms by date of repatriation. Where multiple flights departed on the same day the points are offset. Solid green line represents predicted prevalence over time following fitting of a logistic regression model to binomial count data, dashed lines represent the 95% CI of these estimates (p-value = 0.11). Supplementary table: Summary of testing procedures where available for countries who repatriated citizens from Wuhan City, China.

Country of PCR Testing Information on Testing Procedures References Quarantine Tested only if a person becomes symptomatic during quarantine, with medical health checks daily. Before release repatriates were “medically Link1;Link2;Link3 Australia Yes cleared” and were screened for symptoms throughout quarantine – inferred did not test everyone Tested upon arrival in quarantine and then again before release from Link4;Link5;Link6 Austria Yes quarantine, and if a person was symptomatic during quarantine. No information Bangladesh found Belgium Yes All evacuees were tested six times during quarantine. Link7 Tested three times during quarantine, on arrival with results on the 11th Link8;Link9;Link1 Feb 2020, the second tests on 17th Feb 2020 with results on 19th Feb Brazil Yes 0; Link 70 2020. The final tests were performed on 21st Feb 2020 with results on 22nd Feb 2020 No information Brunei found Bulgaria Yes Tested everyone in quarantine at least once. Tested on arrival. Link11;Link12

Tested if person becomes symptomatic during quarantine and medically Link13;Link14;Lin Canada Yes cleared after quarantine period ended – inferred did not test everyone k15

Tested everyone on the day of arrival with routine medical checks during Colombia Yes quarantine and testing anyone who is symptomatic. Will test on day 7 and Link16; Link67 14 of quarantine Czech Yes Tested everyone at least once Link17 Republic Tested everyone upon arrival - then citizens went into home quarantine Denmark Yes with temperature monitoring and daily outreach from health professionals. Link18;Link19 Tested anyone with symptoms. Egypt Yes Tested everyone before release (date unknown) Link20;Link21 Tested everyone several times during quarantine and before release from France Yes Link22 quarantine. Tested everyone on arrival, if symptomatic and before release from Link23;Link24 Germany Yes quarantine. Greece Yes Tested, no additional information. Hungary Tested everyone multiple times Link25 India Yes Tested everyone before release from quarantine Link26 Indonesia No Not testing during quarantine Link27 Iran Yes Tested everyone multiple times Link28 Iraq Unknown Link29 Italy Yes All evacuees tested during quarantine and before release from quarantine Link30;Link31 Tested everyone multiple times during quarantine, on arrival, if Japan Yes Link32 symptomatic and before release Jordan Yes Tested everyone five days after arrival into quarantine Link33; Kazakhstan Yes Tested everyone before release from quarantine Link34 No information Kyrgyzstan found No information Lebanon found Malaysia Yes Repeated testing of everyone Link35 Tested on arrival in Colombia before second repatriation flight to Mexico Mexico Yes and from there are undergoing home quarantine with medical checks with Link68;Link69 health services Mongolia Yes Tested everyone on 3rd Feb 2020 Link36;Link37

Underwent a 20-day quarantine with testing of everyone before release Morocco Yes Link38 from quarantine No information Myanmar Samples sent to Thailand Link39 found Tested everyone on arrival (16-18th Feb 2020), results on 21st Feb 2020, Nepal Yes testing again at the end of 14 days and then follow up tests 2nd March Link40 2020. Evacuees were self-isolating at home and should contact health services Netherlands Yes Link41;Link42 if developed symptoms for testing. Tested if a person becomes symptomatic during quarantine – inferred New Zealand Yes Link43 they did not test everyone Norway Yes Home quarantine with testing of suspected cases Link44;Link45 Philippines Yes Tested if person becomes symptomatic of suspected COVID19 Link46 Tested everyone 4 times during quarantine - cleared before release from Poland Yes Link47 quarantine Link48;Link49 ; Portugal Yes Tested everyone on arrival and before release from quarantine Link 71 Russia Yes Tested everyone on arrival and before release from quarantine Link50 Saudi Arabia Yes Tested everyone twice, on arrival and before release from quarantine Link51 Tested everyone upon arrival, during quarantine and before release from Singapore Yes Link52 quarantine Slovakia Yes Tested everyone on arrival in quarantine Link53 Tested everyone on arrival, if symptomatic and before release from South Korea Yes Link54 quarantine Spain Yes Tested all evacuees on arrival and monitored symptoms Link55 No information Sri Lanka found Evacuees were self-isolating at home and should contact health services Sweden No Link56 if they developed symptoms for testing No information Syria found Tested those upon arrival who were symptomatic and throughout Taiwan Yes Link57 quarantine Thailand Yes Testing everyone on arrival, and if symptomatic Link58 Turkey Yes Tested everyone every three days Link59 UK Yes Tested all evacuees three times during quarantine Link60 Ukraine Yes Tested everyone three days into quarantine Link61 Tested everyone on board the first repatriation flight 195 persons; after USA Yes Link62 this testing only if person becomes symptomatic of suspected COVID19 Uzbekistan Yes Tested before release from quarantine and upon arrival. Link63 Vietnam Yes Tested everyone, unclear at what timing. Link64 Morocco Yes Tested everyone twice Link65;Link66 On arrival everyone was tested – temperature monitoring and daily Colombia Yes Link67 medical checks.