Familial clusters of the 2019 novel coronavirus diseases in Taiwan

Dear Editor:

We agree that home quarantine has been effective in preventing the early transmission of coronavirus disease 2019 (COVID-19) by Wang et al. [1]. As family clusters of COVID-19 with 9 and 11 family members infected in China [2,3], the increased risk of COVID-19 in family members is noteworthy with home quarantines. The outbreak of COVID-19 with 2,160,207 laboratory-confirmed patients diagnosed and 146,088 reported deaths globally on April 18, 2020, by WHO [4]. With the earlier implementation of measures in preventing imported cases, The Taiwanese government has implemented various measures including travel bans since Jan 23, 2020, and home quarantines since Jan 25, 2020 [5]. Total 398 (0.76%) patients were diagnosed out of 52,445 tested individuals in Taiwan with 6 (1.5%) reported deaths as of April 18, 2020 [5]. The investigation for all the confirmed patients by the Taiwan Center for Disease Control greatly helps the tracing of the possibly contacted people and quarantine of them. Of the 398 patients, 43 (10.8%) by 16 family clusters, with 14 (with traveling history together), 5 patients were infected by the spouse when with home quarantine and others (infection transmitted from another family) in each family, were noted (Table 1 ). Particularly, 5 patients were asymptomatic infections (4 Taiwanese No. 18, 92, 356 and 382, and one another foreign temporary caregiver (No.32) after taking care No. 27 for 6 days). It is noteworthy that foreign caregiver's infection implicates another kind of “family cluster” due to close contact and the “occupation acquired infection” which indicates an ominous omen in an emerging infection with home quarantine. Fortunately, there is no new patient who is the caregiver in Taiwan until now [5]. Since only 55 (13.8%) of 398 patients were locally transmitted which may implicate the effective measures to protect the human-to-human transmission of the COVID-19 as the recent report describing the quick response to COVID-19 in Taiwan by Wang et al. [6].

Table 1.

Laboratory-confirmed patients of the 2019 novel coronavirus disease in Taiwan in 16 families (till April 18, 2020).

Patients	Traveling history or contact history	Date for confirmed diagnosis	Family members (patient number)	The period from the first case in the family to the next.	Note
No. 5	Wuhan City, China	January 27, 2020	Husband (No. 8)	5 days	No. 8 is the first indigenous patient reported in Taiwan
No. 10	Wuhan City, China	January 31, 2020	Wife (No. 9)	One day
No. 14, 15, 17, 18	All traveled to Italy and transited through Hong Kong	February, 6, 8, and 9, 2020	Parents and their two sons		No. 18 (21 year-old) is the first asymptomatic case reported in Taiwan
No. 19	Patient is a taxi driver (taking passengers from China)	February, 15, 2020	Younger brother (No. 20), mother (No. 21), nephew-in-law (No.22), sister (No. 23)	One days	No. 19 is the first death in Taiwan
No. 24	Denied (unknown)	February, 19, 2020	Granddaughter (No. 25) and daughter (No. 26)	2 days
No. 29	Wuhan and Guangzhou City, China	February, 24, 2020	Father (No. 27), elder brother (No. 28), mother (No. 30), nephew (No. 31)	One day	No. 32 (31 year-old) is a foreign temporary caregiver taking care No. 27
No 34	In hospital	February 28, 2020	daughter (No. 41), son (No. 46),	3 days
No 71	Egypt	Mar 17, 2020	Son (No. 92)	One day	No. 92 (22 year-old) is an asymptomatic case
No. 170, 189	All traveled to Spain	March 23, 2020	Couple
No. 197, 202	All traveled to USA	March 24, 2020	Couple
No. 172, 173	All traveled to France	March 23, 2020	Couple
No. 290, 291	All traveled to Indonesia	March 29, 2020	Couple
No 269	Europe	March 28, 2020	Son (No. 299)	2 days
No 293	Europe	March 29, 2020	Wife (No. 289)	1 days
No 356	USA	April 3, 2020	Wife (No. 343) Son (5 y/o) (No. 356)	2 days	No 356 (60 year-old) is an asymptomatic case
No 378, 382	All traveled to Indonesia	April 8, 2020 April 10, 2020	Couple		No 382 (63 year-old) is an asymptomatic case

Patient number and data were reported by Taiwan Centers for Disease Control and Taiwan Central Epidemic Command Center (https://www.cdc.gov.tw/En).

The familial transmission may also occur before quarantine. Because the family cluster accounted for 50% (17/34) of Taiwanese patients at the end of February 2020, the education for paying more attention both in families and people living together has been launched. With all travelers having to be in-home quarantine after returning to Taiwan since March 19, 2020, in Taiwan [5], it is important to prevent cross-infection between patients and families particularly, also for many countries around the world implementing a global travel ban due to the widespread of the community infection. The major challenges are preventing the families from COVID-19 by the infected individuals who are asymptomatic especially. Another important lesson from Taiwan is the prevention of health care workers including more than 200 thousand foreign caregivers in Taiwan. In addition to from the occupational safety point of view, they are not just employees but also like family due to living together with the family members. With very hard preparation earlier for fighting the COVID-19, the family clusters have to be specially noticed in the near future in Taiwan.

Author's contributions

Dai CY: Conceptualization; Writing - original draft.

Yu ML: Writing - review & editing.

Jong YJ: Conceptualization; Supervision; Writing - review & editing.

Ho CK: Conceptualization; Supervision; Writing - review & editing;

Funding source

None.

Declaration of competing interest

No conflict of interest for all authors.