COVID-19 transmission case study summary
The following is a summary of the detailed case studies that describe the detailed accounts of interactions between the infectee and infected.
Situation 1. Directed Interactions at a workplace. Germany
Total new infections after the event: 16
Ref. Böhmer et al. Lancet 2020 [18]; Rothe et al. N Engl J Med, 2020 [19]
A visitor from Shanghai (Patient 0) attended a training session in Munich during January 20, 21. A few days before this visit on January 16, Patient 0’s parents visited her in Shanghai from Wuhan. During the meetings in Munich she felt fatigue which she thought was due to jet lag, but fever (38.6) started only on the flight back.
S.1A. Patient 0 sat through a 1 hour meeting 3 others in a 12 m2 room, including Patient 2 who sat on her side of the table. Only Patient 2 contracted the infection.
S.1B. Patient 2 had a brief contact with Patient 1.
S.1C. Patient 3 and Patient 1 worked simultaneously on the same computer for a short period of time on January 24
S.1D. Patient 12 had a private meeting with Patient 3 for 90 min, and later spent time with Patient 3 and Patient 3’s partner. Partner was negative.
S.1E. Patient 4 sat back to back in a canteen and Patient 5 borrowed salt shaker after asking for it
S.1F. Patient 5 is from a 5-member household and Patients 6,9,11 are from it. Since a specific instance cannot be assigned, these cases are not included.
S.1G. Patient 7 met with Patient 5 for a 1.5 hour meeting at 1.5 meters.
S.1H. Patient 8 and Patient 5 had regular meetings Jan 22, 23, 24.
S.1I. Patient 13 accompanied Patient 0 in travel from China and during the work in Munich.
S.1J. Patient 14 is a household member of Patient 7. This case was not included in our analysis.
S.1K. Patient 7 had a 1 hour meeting with Patients 10, 16.
S.1L. Patient 16 in a meeting with patient 8 > 1 m. Duration not known. Also Patient 16 was also likely to have been infected by 7.
Situation 2. Open-floor work place interactions for a few days, with a lot of talking. South Korea
Total new infections after the event: 97
Ref. Park et al., Emerg Infect Dis, 2020 [20]
In a 19 floor building, has call centers on floors 7,8,9,11 with around 200 employees each. COVID-19 broke out on floors 10, 11. Of the 1,143 (99.8%) individuals including employees, residents and visitors 97 (8.5%, CI 7.0–10.3) tested positive. The first case-patient who worked on the 10th floor and reportedly never went to the 11th floor, had symptoms starting from February 22. The case patient from the 11th floor had symptoms from the 25th of February. The call center came under close surveillance on March 8th.
S.2A. According to the graphic given in Park et al., 79 infections were in one half of the 11th floor and only 5 were on the other half (the rest of the 94 cases were not shown in the representation). The two halves shared elevators and restrooms.
S.2B. Total infections on the 11th floor were 94 out of 216.
S.2C. The lobby and elevator by shared by all residents, employees and visitors. Yet the infections were mainly restricted to 11th floor.
S.2D. Metro. The call center is close to two popular metro stations, and many employees use metro services. However, it is hard to trace who all got infected in metro trains. On the other hand the total number of infections reported from anywhere in Seoul during March 7-March 14 was 139, which leaves at most 42 infections that may have been caused by the employees at the call center.
S.2E. Considering all the 1143 (residents, employees, visitors), the attack rate was 97/1143.
Situation 3. Business conference at a hotel for 3 days. Singapore
Total new infections after the event: 7
Ref. Pung et al. Lancet, 2020 [21]
A British company held an annual 3 day international sales conference from January 20th at a Hotel in Singapore. 94 attendees from 19 countries were among the 111 attendees. 17 attendees were from China, at least 1 from Wuhan. Activities included business presentations, workshops, breakout discussions, team building games which involved close physical contact, city tour. Patient B1 (South Korea), B3 (Malaysia) and B4 (Singapore), B7 (British) were at the same tables for 3 hours at the Chinese dinner (20 January) with approximate 8 member round table. B1, B3, B4, B5 were in the same breakout session of 41 participants for 4 hours, along with 10 Chinese team members.
S.3A. In the entire conference with 111 participants, there were 7 new infections at the end (3 Singapore (3/15), 1 British, 2 South Koreans, 1 Malaysian)
S.3B. Two of the infected members were from one dinner table, and three from another.
S.3C. 3 hour workshop where B2, B4, B5 participated. No clear interaction data and hence not used in our analysis.
S.3D. Lion dance troupe spent 5–10 minutes with their lion masks, going around everyone. No personal interaction, did not eat food and did not contract infections.
Situation 4. Driving Together and Family Dinner.
Total new infections after the event: 2
Ref. Pung et al. Lancet, 2020 [21]
The Malaysian attendee to the business conference in Singapore (Situation 3 above) had come in contact with including, family, friends, and medical staff. He caused 2 new infections.
S.4A. He rode in a car with his sister (which we infer as including speaking and sitting side by side)
S.4B. He shared Chinese New Year meals with family January 26, 27,28. His mother-in-law contracted infection. The total number of attendees is not known.
Situation 5. Family dinner for a few hours at Mei Hwan Drive, Singapore.
Total new infections after the event: 7
Ref. Press release from the Ministry of Health, Singapore, Dated 25 February. https://www.moh.gov.sg/news-highlights/details/links-established-between-church-clusters-and-wuhan-travellers
On January 25, there was a small family get together for celebrating Chinese New Year on the Mei Hwan Drive. This was attended by a couple (Case 83, 91) who also attended a service on January 19 at the Life Church.
S5. Nine of the attendees including Patient 66 (who later spread to Grace of God church), 70, 71, 80, 83, 84, 88, 91 got infected at the incident. Whether there was anyone at the dinner who did not contract the disease is not clear.
Situation 6. Large Sit-down Dinner Gathering. Safra Jurong, Singapore
Total new infections after the event: 36
Ref. Press release from the Ministry of Health, Singapore, Dated 8 March.
Around 200 guests attended a sit-down dinner at Safra Jurong on February 15th. As per the regulation, the the attendees were checked for fever, and enquired about a travel history to China in the 14 days before that. All attendees appeared safe as per these criteria, although the Government later announced that there was one person who had symptoms, possibly not fever, attended the event. The dinner, which featured song-and-dance performances and lasted for five hours. There were an estimated 30 tables, and the guests moved between the tables for chit-chat and pictures.
S.6 Within a few days, 36 infections of the attendees were identified. However, considering only 20 families were among them, the remaining 16 could have been either primary infections at the event or secondary infections in the household. We infer the data as all primary infections.
Situation 7. Eating at a Restaurant in Guangzhou, China. Effect of Air conditioning
Total new infections after the event: 9
Ref. Lu et al. Emerg Infect Dis. 2020 [22]
On January 24, a day after returning to Guangzhou from Wuhan, index patient (patient A1) went for a restaurant with 3 other family members (A2–A4). The restaurant is on the third floor of the 5-floor building (145 m2) has its own air coniditioner (AC). Two families B and C with no known history of travel to Wuhan were in the restaurant overlapping around 1 hour each with family A. The seating arrangement showed that they were all in the line of air flow and return (AC ⇄ Family C ⇄ Family A ⇄ Family B). Later that day, patient A1 experienced onset of fever and cough and went to the hospital.
S.7A. On January 24, 91 persons (83 customers who ate lunch at 15 tables, 8 staff members) were in the restaurant. Among the 83 customers, 10 (including the index patient) were ill with COVID-19.
S.7B. Among the people that sat for the longest exposure time, along the airflow direction which could have brought about the mixing, by February 5, 9 members had COVID-19 (4 from family A, 3 from family B, and 2 from family C). The minimum distance to family A was around (B) 1 meter in the direction of flow and 2 meter in the direction of return flow © respectively.
Situation 8. Family home dinner for a few hours
Total new infections after the event: 5
Ref. Zhang et al., Critical Care, 2020. [23]
On January 19, Index patient came back to Bejing from Wuhan. He invited his nephew (Patient 3) for a dinner on the same day. Patients 0, 1, 2, live together, and Patients 3, 4 together and all contracted COVID-19.
S.8. In our analysis only the transmission to Patient 3 at dinner was used and other household transmissions were excluded.
Situation 9. Family home dinner for a few hours in Nanjing, China.
Total new infections after the event: 10
Ref. Huang et al. Lancet, 2020. [24]
On Jan 21, 2020, the index patient left Xiaogan, switched a train in Wuhan and arrived in Nanjing, where she stayed with her sisters (patients 1 and 2) and her mother (patient 3). On Jan 21, she had a dinner with her mother, two sisters, and her brother (patient 4). The index patient had another family dinner with eight relatives on Jan 23. At both these dinners the index patient had no symptoms, but developed cough and fever on Jan 28. Three patients (patients 1–3) who lived together with the index patient and three relatives (patients 4, 6, and 7) who attended the dinner with the index patient on Jan 23 were positive for SARS-CoV-2 infection thereafter. On Jan 24, there was another family dinner with 13 relatives, and two patients (patients 6 and 7) who were still without attended it causing three new infections (patients 8–10). Throughout this familial clusters, the index patients were asymptomatic. Household infections 1,2,3,5 are not used in our analysis.
S.9A. Dinner of Jan 23. Patient 1 attended a dinner with 8 family members, resulting in 3 new infections.
S.9B. Dinner of Jan24. Patients 6,7 attended a dinner with 13 relatives resulting in 3 new infections Patients 8, 9, 10.
Situation 10. Vacation for 3 days in French Alps
Total new infections after the event: 7
Ref. Hodcroft, Swiss Med. Wkly, 2020. [25]
A British citizen flew after the sales training conference in Singapore from 20–23 January (Situation 3) and joined his family and friends for a 4 day vacation in a Chalet in French Alps on January 24. The group skied, dined together and mostly stayed indoors interacting. He flew back to England on the 28th of January.
S.10 Of the 11 people that were identified as the close contacts to the index patient — 5 infections (in total, including a 9-year-old boy) were detected in France, 1 upon returning to Mallorca and the index patient was diagnosed in England in early February.
Situation 11. Sharing a room for a few days
Total new infections after the event: 1
Ref. Phan et al. N. Engl. J. Med, 2020 [26]
A couple returned from a travel to Wuhan (although they were not exposed to the wet markets), and for three nights from January 17, they shared a hotel room with an air-conditioner in Vietnam with their son. The son had no other known exposure to infection.
S.11 By January 20, the son developed dry cough and was later diagnosed as infected.
Case 12. Attending a gathering for few hours, with too many people and singing
Total new infections after the event: 7
Ref. Kim et al. medRxiv 2020 and the associated data [27]
https://github.com/yejinjkim/covid19-transmission-network/tree/master/data
Press release dated 24 March 2020, By the CDC Korea, https://www.cdc.go.kr/board/board.es?mid=a30402000000&bid=0030
On February 7, a person who will later be labeled as Patient 31 was admitted to hospital for an accident. On February 9 she attended a 2 hour service at the Shincheonji church, and another similar session on the 16th of February. Altogether 9300 attended these two services. In these services, usually no face masks or glasses were allowed, and usually people sat in very close arrays to reach the shoulders of neighbors, sang for about 30 minutes, and possibly engaged in potluck meals. She developed fever symptoms on the 10th of February, and was announced COVID-19 positive on 18th February. By March 25, more than 5000 cases could be linked to the Shincheonji cluster.
S.12A. Patient 31 was related to 1160 contacts, and was responsible for 7 infections at the Shincheonji church (from the data sheets in the Supplementary Information of Kim et al. 2020)
S.12B. Patient 31 also caused 10 infections outside the Church. (from the data sheets in the Supplementary Information of Kim et al. 2020)
Situation 13. Closed space gathering for a few hours
S.13A. Life Church cluster in Singapore.
Total new infections after the event: 6
Ref. Pung et al. Lancet, 2020 [21]
On January 19, 142 of the 227 regular church goers attended a 2 hour long service, to which a couple (case 8, case 9) who returned from Wuhan on the same day visited. The result was 6 infections (Case 31, case 33, case 38, case 83, case 90, case 91). No details of where they sat or how they interacted with the two index patients are known.
S.13B. Grace Assembly of God cluster in Singapore
Total new infections after the event: 9
Ref. Ministry of Health, Singapore, Press release
Case 66 in Singapore who attended the Mei Hwan Drive dinner, attended two sessions at the Grace Assembly of God church. The staff devotion meeting on 29 January, where case 51,48,49 were present. At the prayer meeting, on February 5th there were Case 48, 66, 49. And resulted in 3 staff (54,57,60) and 6 visitors (53, 61, 62, 63,67,73) got infected. The total number of attendees is not known.
Situation 14. Singing together for a few hours. Choir in Washington
Total new infections after the event:52
Ref. Hamner et al., MMWR Morb Mortal Wkly Rep 2020 [28]
On March 10th 61 of the 122 member Choir attended a rehearsal between 6:30 to 9:00 pm. By March 12 at least six members of the group had developed fever and communicated it to its director. The index patient was later identified as someone who had onset of symptoms on March 7. During the practice, the 61 members occupied the seating arrangement of six rows of 20 chairs each at 6–10 inch distance (seating plan not disclosed by the authorities). There are reasons to believe a strong mixing in the group as there was a 40 minutes joint practice session, other sessions of 50 minutes in two smaller groups, snack break for 15 minutes and gathered together to restore the chairs to the racks.
S.14 Among 61 persons who attended a March 10 choir practice at which one person was known to be symptomatic, 53 cases were identified.
Situation 15. Singing in a closed space
Total new infections after the event: 3
Ref. W. E. Wei, et al., MMWR Morb Mortal Wkly Rep. 2020 [29]
S.15A. On February 15, Patient B1 attended a dinner where she was exposed to a COVID-19 positive patient. On February 24, patient B2 and patient B1 attended the same singing class. Patients B1 and B2 developed symptoms on February 26 and 29, respectively.
S.15B. Patient F1 attended a singing class on February 27th, where she was exposed to a COVID-19 positive patient. On March 1 F1 attended a Church service an infected Patients F2, F3 who were one row behind her. Patient F1 and F2, developed symptoms on March 3rd, and F3 on March 5th.
Situation 16. Shopping for a few hours with direct contacts with sales agents. Singapore
Total new infections after the event: 10
Ref. Pung et. al. Lancet, 2020 [21]
A tourist group of 20 visited Singapore on January 22, 23 from Guangxi, China. During the tour five or six were suspected to be coughing, although only two of them later tested positive on January 28 (father and daughter AGX1, AGX2).
S.16A. The tourist guide (AT1) who interacted with them for a day was COVID-19 positive. However, this is a continuous exposure, with a lot of talking for a complete day and hard to track the interactions. Hence we do not consider this case in our analysis.
S.16B. The group visited a jewelry shop for 1 hour, and the agent who interacted with them AJ1 tested positive. AJ1 also happens to be the husband of AT1, however, since the tour spent 1 hour with AT1, we classify this as a potential direct infection.
S.16C. The group also visited a complementary health products shop where the 4 sales agents who interacted with them tested positive. The sales agents in the shop typically apply products on the customers, and usually do not have handwash in between customers. There were 16 staff altogether, but possibly only 4 interacted with the group.
S.16D. At the home of the tourist guide AT1, there were two other infections 6-month old child and domestic help. However, the length of interactions not known and hence not included in our analysis.
Situation 17. Attending night clubs with too many people for a few hours. Itaewon cluster, South Korea
Total new infections after the event: 94 as of May 19
Ref. Information and numbers of infected people from the Press Releases of CDC Korea, May 19th.
https://www.cdc.go.kr/board/board.es?mid=a30402000000&bid=0030
Consistent account reconstruction from multiple media reports.
https://www.straitstimes.com/asia/east-asia/s-korea-delays-school-reopening-as-club-cluster-grows
https://time.com/5834991/south-korea-coronavirus-nightclubs/
https://en.yna.co.kr/view/AEN20200509001452315
On April 30, a 29 year old spent a day at the resort with three friends. After returning, he and one of the friends he traveled with, went to party at 5 night clubs between the night of May 1 and early hours of May 2. The club, as per the regulations tested for temperature, asked for travel history and noted their contact details. However, nothing looked suspicious. However, the index patient had a high fever and diarrhoea on the evening of May 3 and tested positive on May 6.
S.17A. Resort stay with 1+3 friends caused 1 new infection. 2 other friends tested negative.
S.17B. The turnout at the clubs was 1500. The press releases mention that 94 infections are caused during May 2–3 among the club-goers, in addition to more than 90 secondary infections. We infer that most, if not, all of these 94 primary cases may be attributable to the couple of friends. The reasons being that they visited they were in 2, and visited 5 different heavily crowded places, which already is likely to create sufficient new infections. The chance that others who were infected on May 2 early hours, became infectious, and visited the clubs again on May 3 early hours makes it less likely that the 94 infections were caused by individuals other than the two friends.
S.17C. One of the persons who was infected at the club is a teacher in Incheon, and subsequently infected at least 15, in which there were 8 middle and high school students, a female middle school student privately tutored by the instructor, her twin brother and their mother. However, the detailed interactions of how this teacher contracted or transmitted infections is not known and hence it is not included in our analyses.
Situation 18. Funeral followed by a birthday party in Chicago.
Total new infections after the event: 15
Ref. Ghinai et al. MMWR Morb Mortal Wkly Rep, 2020 [30]
In February 2020, a funeral was held in Chicago for a person who died of a non-COVID-19 causes. The index patient (A1.1), a close friend of the family, had recently travelled out of the state and experiencing mild respiratory symptoms had attended the funeral.
S18A. The evening before the funeral, patient A1.1 shared a 3 hour long meal, eaten from common serving dishes, with two family members (patients B2.1 and B2.2) of the deceased at their home. At the funeral which lasted about 2 hours and involved a “potluck-style” meal, patient A1.1 to express condolences embraced the family members B2.1, B2.2, B2.3, and B3.1 of the deceased. Patients B2.1, B2.2, B2.3 developed symptoms within 2, 4 and 6 days respectively after the funeral.
S.18B. Three days after the funeral, patient A1.1, attended a birthday party attended by nine other family members at the home of A2.1. Patient A1.1 embraced others and shared food at the 3-hour party, and close contact between A1.1 and all other attendees is reported. Seven party attendees, Patients A2.1 to A2.7 were infected.
S.18C. A few days after the birthday party, patients A2.5, A2.6, and A2.7 attended a Church where they spoke to a healthcare professional ((patient D3.1) with no other known exposure to COVID-19 for 90 minutes, within a 1 row distance and the offering plate was passed. D3.1 was symptomatic within a day.
Situation 19. Two different birthday parties
Total new infections after the event: 25
Ref. https://www.nytimes.com/2020/03/23/us/coronavirus-westport-connecticut-party-zero.html
S.19A. Birthday in Connecticut. On March 5th, 50 guests from across US and abroad attended a birthday party at home in a wealthy suburb in Connecticut. About half of the attendees to this lavish buffet meal were infected. No one had symptoms at the party, the first reported symptoms were by a person who felt sick on the flight back home. The positive cases went back to other cities in USA as well as to other countries.
Situation 19. Birthday party in California
Total new infections after the event: 20
An April birthday party in Pasadena with an estimated 30–40 attendees had 5 confirmed cases, many others (> 20 with symptoms). One of the guests at the event was coughing. No masks were used, no social distancing was maintained.
Situation 20. On board Cruises and Ships, for a few weeks
S.20 A. Diamond Princess
Total new infections after the event: 634
Ref. Kenji et al., Euro Surveill. 2020 [31]
An 80-year-old passenger traveled from Yokohama to Hong Kong. Six days after disembarking the ship, on February 1, she tested positive and on February 3, Diamond Princess was put into quarantine. By 21 February, 634 out of 3,711 passengers and crew members on board Diamond Princess cruise tested positive.
S.20 B. US aircraft carrier Theodore Roosevelt
Total new infections after the event: 1,102
Theodore Roosevelt in early March had on board a few sailors that stayed in a hotel in Vietnam where two people tested positive. After staying at sea for more than a month, 1,102 out of the total crew of 4,500 tested positive.
S.20 C. The French navy’s Charles de Gaulle
Total new infections after the event: 1,081
Charles de Gaulle was at sea for more than a month, and 1,081 of the nearly 1800 crew members tested COVID-19 positive.
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