Since the end of January 2020, in response to the growing COVID-19 epidemic, 55 countries have repatriated over 8000 citizens from Wuhan City, China. In addition to quarantine measures for returning citizens, many countries implemented PCR screening to test for infection regardless of symptoms. These flights therefore give estimates of infection prevalence in Wuhan over time. Between 30th January and 1st February (close to the peak of the epidemic in Wuhan), infection prevalence was 0.87% (95% CI: 0.32% - 1.89%). As countries now start to repatriate citizens from Iran and northern Italy, information from repatriated citizens could help inform the level of response necessary to help control the outbreaks unfolding in newly affected areas

Baguelin, M

Bhatia, S

Boonyasiri, A

Cori, A

Cucunuba Perez, Z

Cuomo-Dannenburg, G

Dighe, A

Donnelly, C

Dorigatti, I

Ferguson, N

Fitzjohn, R

Fu, H

Gaythorpe, K

Ghani, A

Green, W

Hamlet, A

Hinsley, W

Imai, N

Laydon, D

Nedjati Gilani, G

Okell, L

Riley, S

Thompson, H

Van Elsland, S

Volz, E

Wang, H

Whittaker, C

Xi, X

Yuanrong, W

English

Spiral - Imperial College Digital Repository

   09 March 2020  Imperial College London  DOI: https://doi.org/10.25561/77295   Page 1 of 10  Report 7: Estimating infection prevalence in Wuhan City from repatriation flights WHO Collaborating Centre for Infectious Disease Modelling MRC Centre for Global Infectious Disease Analysis Abdul Latif Jameel Institute for Disease and Emergency Analytics (J-IDEA)  Imperial College London Hayley Thompson, Natsuko Imai, Amy Dighe, Marc Baguelin, Sangeeta Bhatia, Adhiratha Boonyasiri, Anne Cori, Zulma Cucunubá, Gina Cuomo-Dannenburg, Ilaria Dorigatti, Rich FitzJohn, Han Fu, Katy Gaythorpe, Azra Ghani, Will Green, Arran Hamlet, Wes Hinsley, Daniel Laydon, Gemma Nedjati-Gilani, Lucy Okell, Steven Riley, Sabine van Elsland, Erik Volz, Haowei Wang, Yuanrong Wang, Charlie Whittaker, Xiaoyue Xi, Christl A. Donnelly, Neil M. Ferguson* *Corresponding author: neil.ferguson@imperial.ac.uk  Summary Since the end of January 2020, in response to the growing COVID-19 epidemic, 55 countries have repatriated over 8000 citizens from Wuhan City, China. In addition to quarantine measures for returning citizens, many countries implemented PCR screening to test for infection regardless of symptoms. These flights therefore give estimates of infection prevalence in Wuhan over time. Between 30th January and 1st February (close to the peak of the epidemic in Wuhan), infection prevalence was 0.87% (95% CI: 0.32% - 1.89%). As countries now start to repatriate citizens from Iran and northern Italy, information from repatriated citizens could help inform the level of response necessary to help control the outbreaks unfolding in newly affected areas.             SUGGESTED CITATION Hayley Thompson, Natsuko Imai, Amy Dighe et al. Estimating infection prevalence in Wuhan City from repatriation flights. Imperial College London (09-03-2020), doi: https://doi.org/10.25561/77295.  This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.    09 March 2020  Imperial College London  DOI: https://doi.org/10.25561/77295   Page 2 of 10  1. Background Following the outbreak of a novel coronavirus (COVID-19, formerly 2019-nCoV) in Wuhan City, China and the subsequent travel and movement restrictions implemented in the city, foreign governments began the process of chartering flights to repatriate citizens from the epicentre of the outbreak. These flights began on 29th January 2020 and continued throughout February with the last flight returning on 27th February 2020.   In addition to quarantining citizens returning on these flights to prevent any potential secondary transmission after arrival, many countries implemented PCR screening of returning citizens to test for infection. These repatriation flights therefore provide snapshots of the infection prevalence over time and insights into the levels of transmission in Wuhan City. We present an overview of these repatriation flights within this timeframe. Information on: i) the number of individuals repatriated; ii) their destination country; iii) whether individuals were tested for the pathogen responsible for COVID-19 regardless of symptoms; iv) and their outcomes where available were sourced from publicly available sources. These are provided in a supplementary data file.  2. Results A total of 8597 persons have been repatriated over 56 flights from Wuhan City carrying citizens from 55 different countries (Table 1). The first flight left Wuhan on 29 January 2020 and the last flight left almost a month later on 27th February 2020. In addition, there were 3 flights repatriating citizens from Beijing to Kazakhstan and Kyrgyzstan. Figure 1 highlights the countries (and the number of repatriation flights by country) where repatriated persons have been undergoing 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 as such 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 charter flights in country. Most countries implemented 14-day quarantine periods to help mitigate the potential for local onward transmission from this at-risk population. This follows WHO advice based on estimates that the maximum incubation period of the virus is 14 days [1]. During this time, most, but not all, countries have tested for the presence of coronavirus in symptomatic and asymptomatic repatriates, at multiple time points. The supplementary table outlines the testing procedures that have been made publicly available.     09 March 2020  Imperial College London  DOI: https://doi.org/10.25561/77295   Page 3 of 10   Figure 1: Countries where citizens who have been evacuated from Wuhan City have undergone quarantine. Note some countries offered quarantine for citizens of other countries and as such these nations while having repatriated citizens are not shown in this map.   While screening procedures varied, we have been able to identify 47 flights that screened for COVID-19 infection in their evacuees. This resulted in a total screened population of 5720, of these evacuees a total of 36 tested positive for the novel coronavirus resulting in an overall infection prevalence of 0.63% (95% CI: 0.44% - 0.87%). However, only 32 out of the 47 repatriation flights implementing testing 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%). It is important to note that at the time of analysis (6 March 2020) some evacuees had not yet completed their 14-day quarantine period and therefore may still test positive. For the passengers of the 30 flights which have completed the 14-day quarantine period, the overall infection prevalence was 0.61% (95% CI: 0.41% - 0.88%). Finally, repatriation flights had different testing protocols (supplementary table), and amongst the 47 flights that screened for COVID-19 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 be 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 30 January and 1 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%).      09 March 2020  Imperial College London  DOI: https://doi.org/10.25561/77295   Page 4 of 10  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. Although not all repatriated flights have completed their 14-day quarantine periods, infection prevalence was generally low (<3%) across these flights. We also observe a similar trend in infection prevalence over time amongst the repatriated individuals to the observed epidemic trend in Wuhan City thus far [2].  Figure 2: Infection prevalence (points, bars = exact binomial 95% CI) amongst repatriation flights where all passengers were tested for COVID-19 regardless of symptoms by date of repatriation. Where multiple flights departed on the same day the points are offset.  3. Conclusion The number of new cases reported from Wuhan City has declined substantially in recent weeks indicating a declining epidemic at the epicentre. Although it remains to be seen if this decline can be sustained after travel restrictions are lifted in the city, our estimates of infection prevalence over time from repatriation flights supports this decline. However, available information on testing protocols and the delay from repatriation to testing was sparse. The conditions of quarantine are also likely to differ by country. Thus, analysis primarily considered the infection prevalence amongst individuals from repatriation flights who were tested upon arrival. These estimates of infection prevalence provide important insights into the potential level of transmission within the first affected region. As countries now start to repatriate citizens from Iran and northern Italy, information from repatriated citizens could inform the level of response necessary to help control the outbreaks unfolding in newly affected areas.    09 March 2020  Imperial College London  DOI: https://doi.org/10.25561/77295   Page 5 of 10   4. References 1.  World Health Organization. Key considerations for repatriation and quarantine of travellers in relation to the outbreak of novel coronavirus 2019-nCoV. 2020 [cited 2 Mar 2020]. Available: https://www.who.int/news-room/detail/30-01-2020-statement-on-the-second-meeting-of-the-international- 2.  The Novel Coronavirus Pneumonia Emergency Response Epidemiology Team. The Epidemiological Characteristics of an Outbreak of 2019 Novel Coronavirus Diseases (COVID-19) — China, 2020. China CDC Wkly. 2: 113–122.     09 March 2020  Imperial College London  DOI: https://doi.org/10.25561/77295   Page 6 of 10  Table 1: Summary of repatriation flight from Wuhan City, China Flight ID Date repatriated Num repatriated Num tested Total positive confirmed Point tested Positive at initial test Symptomatic at initial test Asymptomatic at initial test Later developed symptoms Total symptomatic Remained asymptomatic Date quarantine ended Quarantine ended* 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 - 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 0 0 0 0 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    09 March 2020  Imperial College London  DOI: https://doi.org/10.25561/77295   Page 7 of 10  Table 1: Summary of repatriation flight from Wuhan City, China Flight ID Date repatriated Num repatriated Num tested Total positive confirmed Point tested Positive at initial test Symptomatic at initial test Asymptomatic at initial test Later developed symptoms Total symptomatic Remained asymptomatic Date quarantine ended Quarantine ended* 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. uzbekistan_fl2 2020-02-05 84 84 0 arrival 0 0 0 0 0 0 2020-02-19 yes newzealand_fl1 2020-02-05 193 2 0 unknown 0 0 0 0 0 0 2020-02-19 yes 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 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 no colombia_fl1 2020-02-27 15 15 0 arrival 0 0 0 0 0 0 NA no 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.    09 March 2020  Imperial College London  DOI: https://doi.org/10.25561/77295   Page 8 of 10  Supplementary table: Summary of testing procedures where available for countries who repatriated citizens from Wuhan City, China Country of Quarantine PCR Testing Information on Testing Procedures   References  Australia  Yes Tested only if a person becomes symptomatic during quarantine, with medical health checks daily. Before release repatriates were “medically cleared” and were screened for symptoms throughout quarantine – inferred did not test everyone  Link1;Link2;Link3  Austria  Yes Tested upon arrival in quarantine and then again before release from quarantine, and if a person was symptomatic during quarantine.  Link4;Link5;Link6  Bangladesh No information found   Belgium Yes All evacuees were tested six times during quarantine.  Link7 Brazil Yes Tested three times during quarantine, on arrival, the second tests on 17th Feb 2020 with results on 19th Feb 2020. The final tests were performed on 21st Feb 2020 with results on 22nd Feb 2020 Link8;Link9;Link10  Brunei No information found   Bulgaria Yes Tested everyone in quarantine at least once. Tested on arrival. Link11;Link12  Canada Yes  Tested if person becomes symptomatic during quarantine and medically cleared after quarantine period ended – inferred did not test everyone  Link13;Link14;Link15   Colombia  Tested everyone on the day of arrival with routine medical checks during quarantine and testing anyone who is symptomatic.  Link16; Link67 Czech Republic  Tested everyone at least once   Link17 Denmark  Yes Tested everyone upon arrival - then citizens went into home quarantine with temperature monitoring and daily outreach from health professionals. Tested anyone with symptoms.    Link18;Link19  Egypt  Yes Tested everyone before release (date unknown) Link20;Link21 France Yes Tested everyone several times during quarantine and before release from quarantine.  Link22  Germany Yes Tested everyone on arrival, if symptomatic and before release from quarantine.  Link23;Link24  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    09 March 2020  Imperial College London  DOI: https://doi.org/10.25561/77295   Page 9 of 10  Iran Yes Tested everyone multiple times Link28 Iraq   Unknown Link29 Italy  Yes All evacuees tested during quarantine and before release from quarantine  Link30;Link31  Japan Yes Tested everyone multiple times during quarantine, on arrival, if symptomatic and before release Link32 Jordan  Yes Tested everyone five days after arrival into quarantine  Link33; Kazakhstan Yes  Tested everyone before release from quarantine  Link34  Kyrgyzstan  No info   Lebanon No info   Malaysia  Yes Repeated testing of everyone  Link35 Mexico  Yes Tested on arrival in Colombia before second repatriation flight to Mexico and from there are undergoing home quarantine with medical checks with health services  Link68;Link69  Mongolia  Tested everyone on 3rd Feb 2020 Link36;Link37  Morocco  Yes Underwent a 20-day quarantine with testing of everyone twice before release from quarantine  Link38; Link65;Link66  Myanmar No information found Samples sent to Thailand Link39 Nepal Yes  Tested everyone on arrival (16-18th Feb 2020), results on 21st Feb 2020, testing again at the end of 14 days and then follow up tests 2nd March 2020. Link40 Netherlands Yes Evacuees were self-isolating at home and should contact health services if developed symptoms for testing.  Link41;Link42  New Zealand Yes Tested if a person becomes symptomatic during quarantine – inferred they did not test everyone Link43 Norway  Yes Home quarantine with testing of suspected cases  Link44;Link45 Philippines Yes Tested if person becomes symptomatic of suspected COVID19 Link46 Poland  Yes Tested everyone 4 times during quarantine - cleared before release from quarantine  Link47 Portugal  Yes Tested everyone on arrival and before release from quarantine Link48;Link49  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 Singapore Yes Tested everyone upon arrival, during quarantine and before release from quarantine Link52    09 March 2020  Imperial College London  DOI: https://doi.org/10.25561/77295   Page 10 of 10  Slovakia  Yes Tested everyone on arrival in quarantine Link53 South Korea Yes Tested everyone on arrival, if symptomatic and before release from quarantine  Link54 Spain Yes  Tested all evacuees on arrival and monitored symptoms Link55 Sri Lanka No information found   Sweden No Evacuees were self-isolating at home and should contact health services if they developed symptoms for testing  Link56 Syria  No information found   Taiwan Yes Tested those upon arrival who were symptomatic and throughout quarantine  Link57 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 USA  Yes Tested everyone on board the first repatriation flight 195 persons; after this testing only if person becomes symptomatic of suspected COVID19 Link62 Uzbekistan Yes Tested before release from quarantine and upon arrival. Link63 Vietnam Yes Tested everyone, unclear at what timing. Link64  

Report 7: Estimating infection prevalence in Wuhan City from repatriation flights

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Report 7: Estimating infection prevalence in Wuhan City from repatriation flights

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