Volume 26, Number 7—July 2020
Research Letter
Severe Acute Respiratory Syndrome Coronavirus 2 Shedding by Travelers, Vietnam, 2020
, and Duc Anh Dang
Table
Characteristics of patients within 2 clusters of severe acute respiratory syndrome coronavirus 2 infection in Hanoi, Vietnam, December 2019–February 2020*
| Cluster, contact period, patient no. (relationship) | Age/sex | Possible incubation period, d† | Disease onset | Symptom onset to sample collection, d | Virus shedding period, d‡ | |||
|---|---|---|---|---|---|---|---|---|
| Virus genome levels, Ct |
||||||||
| E gene | RdRp gene | N gene | ||||||
| Cluster 1: Travelers returning from Wuhan | ||||||||
| 2019 Nov 15–2020 Jan 17 | ||||||||
| 1 | 25 y/F | 7 | Jan 24 | 0 | 25.1 | 28.0 | 28.3 | 7 |
| 2 | 29 y/M | 4 | Jan 21 | 5 | 35.3 | 38.6 | 38.0 | 6 |
| 3 | 23 y/F | 8 | Jan 25 | 2 | 32.0 | 34.7 | 34.6 | 6 |
| 4 | 29 y/F | 12 | Jan 29 | 4 | 30.2 | 37.1 | 27.7 | 7 |
| 5 | 30 y/M | 9 | Jan 26 | 6 | 28.4 | >40.0 | 30.0 | 1 |
| 6 |
30 y/F |
14 |
Jan 31 |
0 |
33.2 |
>40.0 |
35.1 |
7 |
| Cluster 2: Contact with patient 3 | ||||||||
| 2020 Jan 17–24, 28 | ||||||||
| 7 (mother) | 49 y/F | 6 | Feb 3 | 1 | 28.1 | >40.0 | 32.5 | 9 |
| 8 (sister) | 16 y/F | 7 | Feb 4 | 0 | 28.8 | >40.0 | 23.3 | 9 |
| 9 (father)§ | 50 y/M | NA | Feb 4¶ | NA | >40.0 | >40.0 | >40.0 | 9 |
| NA | Feb 11 | NA | 30.0 | 34.0 | 33.0 | |||
| NA | Feb 18 | NA | 26.0 | 28.0 | 30.0 | |||
| 2020 Jan 22, 28 | ||||||||
| 10 (cousin) | 42 y/F | 4 | Feb 1 | 2 | 29.4 | 36.0 | 31.4 | 4 |
| 2020 Jan 28 | ||||||||
| 11 (neighbor) | 55 y/F | 3 | Jan 31 | 6 | 23.0 | 30.0 | 28.0 | 6 |
| 2020 Jan 28–Feb 3, contact with patients 10 and 11 | ||||||||
| 12 (grandchild of patient 10)# | 3 mo/M | 3 | Feb 6 | 0 | 30.0 | 30.9 | 30.8 | 8 |
*Ct, cycle threshold; NA, not applicable because patient was asymptomatic; RdRp, RNA-dependent RNA polymerase.
†Possible incubation period calculation was based on last day of possible contact with patients and onset of disease. Cluster 1 travelers had returned from Wuhan, China, on January 17, 2020, on the same flight from Guangzhou, China, to Hanoi, Vietnam. All cluster 2 patients had contact with patient 3 of cluster 1. Although patient 3 returned from the epicenter of the outbreak and is the only patient with a link to cluster 2, the possibility of virus transmission between patients within the same cluster cannot be ruled out.
‡Virus shedding period was the interval from the day on which a sample was positive by real-time PCR to the day on which virus RNA was negative by real-time PCR. Real-time PCR was performed to detect 3 genes of the severe acute respiratory syndrome coronavirus 2 virus; namely, the E, N, and RdRp genes. Ct values >40.0 were considered negative.
§Patient was virus positive by real-time PCR on 2 consecutively collected samples.
¶Denotes sampling date because this patient was asymptomatic
#Patient had no direct contact with persons in cluster 1 but had close contact with persons in cluster 2.
1These authors contributed equally to this article.